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  13 <big><strong><span class="block">&nbsp;perl5004delta - what's new for perl5.004</span></strong></big>
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  16
  17 <p><a name="__index__"></a></p>
  18 <!-- INDEX BEGIN -->
  19
  20 <ul>
  21
  22         <li><a href="#name">NAME</a></li>
  23         <li><a href="#description">DESCRIPTION</a></li>
  24         <li><a href="#supported_environments">Supported Environments</a></li>
  25         <li><a href="#core_changes">Core Changes</a></li>
  26         <ul>
  27
  28                 <li><a href="#list_assignment_to__env_works">List assignment to %ENV works</a></li>
  29                 <li><a href="#change_to_can_t_locate_foo_pm_in__inc_error">Change to ``Can't locate Foo.pm in @INC'' error</a></li>
  30                 <li><a href="#compilation_option__binary_compatibility_with_5_003">Compilation option: Binary compatibility with 5.003</a></li>
  31                 <li><a href="#_perl5opt_environment_variable">$PERL5OPT environment variable</a></li>
  32                 <li><a href="#limitations_on_m__m__and_t_options">Limitations on <strong>-M</strong>, <strong>-m</strong>, and <strong>-T</strong> options</a></li>
  33                 <li><a href="#more_precise_warnings">More precise warnings</a></li>
  34                 <li><a href="#deprecated__inherited_autoload_for_nonmethods">Deprecated: Inherited <code>AUTOLOAD</code> for non-methods</a></li>
  35                 <li><a href="#previously_deprecated__overload_is_no_longer_usable">Previously deprecated %OVERLOAD is no longer usable</a></li>
  36                 <li><a href="#subroutine_arguments_created_only_when_they_re_modified">Subroutine arguments created only when they're modified</a></li>
  37                 <li><a href="#group_vector_changeable_with___">Group vector changeable with <a href="file://C|\msysgit\mingw\html/pod/perlvar.html#item___"><code>$)</code></a></a></li>
  38                 <li><a href="#fixed_parsing_of____digit______digit___etc_">Fixed parsing of $$&lt;digit&gt;, &amp;$&lt;digit&gt;, etc.</a></li>
  39                 <li><a href="#fixed_localization_of___digit_______etc_">Fixed localization of $&lt;digit&gt;, $&amp;, etc.</a></li>
  40                 <li><a href="#no_resetting_of____on_implicit_close">No resetting of $. on implicit close</a></li>
  41                 <li><a href="#wantarray_may_return_undef"><code>wantarray</code> may return undef</a></li>
  42                 <li><a href="#eval_expr_determines_value_of_expr_in_scalar_context"><a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_eval"><code>eval EXPR</code></a> determines value of EXPR in scalar context</a></li>
  43                 <li><a href="#changes_to_tainting_checks">Changes to tainting checks</a></li>
  44                 <li><a href="#new_opcode_module_and_revised_safe_module">New Opcode module and revised Safe module</a></li>
  45                 <li><a href="#embedding_improvements">Embedding improvements</a></li>
  46                 <li><a href="#internal_change__filehandle_class_based_on_io____classes">Internal change: FileHandle class based on IO::* classes</a></li>
  47                 <li><a href="#internal_change__perlio_abstraction_interface">Internal change: PerlIO abstraction interface</a></li>
  48                 <li><a href="#new_and_changed_syntax">New and changed syntax</a></li>
  49                 <li><a href="#new_and_changed_builtin_constants">New and changed builtin constants</a></li>
  50                 <li><a href="#new_and_changed_builtin_variables">New and changed builtin variables</a></li>
  51                 <li><a href="#new_and_changed_builtin_functions">New and changed builtin functions</a></li>
  52                 <li><a href="#new_builtin_methods">New builtin methods</a></li>
  53                 <li><a href="#tiehandle_now_supported">TIEHANDLE now supported</a></li>
  54                 <li><a href="#malloc_enhancements">Malloc enhancements</a></li>
  55                 <li><a href="#miscellaneous_efficiency_enhancements">Miscellaneous efficiency enhancements</a></li>
  56         </ul>
  57
  58         <li><a href="#support_for_more_operating_systems">Support for More Operating Systems</a></li>
  59         <ul>
  60
  61                 <li><a href="#win32">Win32</a></li>
  62                 <li><a href="#plan_9">Plan 9</a></li>
  63                 <li><a href="#qnx">QNX</a></li>
  64                 <li><a href="#amigaos">AmigaOS</a></li>
  65         </ul>
  66
  67         <li><a href="#pragmata">Pragmata</a></li>
  68         <li><a href="#modules">Modules</a></li>
  69         <ul>
  70
  71                 <li><a href="#required_updates">Required Updates</a></li>
  72                 <li><a href="#installation_directories">Installation directories</a></li>
  73                 <li><a href="#module_information_summary">Module information summary</a></li>
  74                 <li><a href="#fcntl">Fcntl</a></li>
  75                 <li><a href="#io">IO</a></li>
  76                 <li><a href="#math__complex">Math::Complex</a></li>
  77                 <li><a href="#math__trig">Math::Trig</a></li>
  78                 <li><a href="#db_file">DB_File</a></li>
  79                 <li><a href="#net__ping">Net::Ping</a></li>
  80                 <li><a href="#objectoriented_overrides_for_builtin_operators">Object-oriented overrides for builtin operators</a></li>
  81         </ul>
  82
  83         <li><a href="#utility_changes">Utility Changes</a></li>
  84         <ul>
  85
  86                 <li><a href="#pod2html">pod2html</a></li>
  87                 <li><a href="#xsubpp">xsubpp</a></li>
  88         </ul>
  89
  90         <li><a href="#c_language_api_changes">C Language API Changes</a></li>
  91         <li><a href="#documentation_changes">Documentation Changes</a></li>
  92         <li><a href="#new_diagnostics">New Diagnostics</a></li>
  93         <li><a href="#bugs">BUGS</a></li>
  94         <li><a href="#see_also">SEE ALSO</a></li>
  95         <li><a href="#history">HISTORY</a></li>
  96 </ul>
  97 <!-- INDEX END -->
  98
  99 <hr />
 100 <p>
 101 </p>
 102 <h1><a name="name">NAME</a></h1>
 103 <p>perl5004delta - what's new for perl5.004</p>
 104 <p>
 105 </p>
 106 <hr />
 107 <h1><a name="description">DESCRIPTION</a></h1>
 108 <p>This document describes differences between the 5.003 release (as
 109 documented in <em>Programming Perl</em>, second edition--the Camel Book) and
 110 this one.</p>
 111 <p>
 112 </p>
 113 <hr />
 114 <h1><a name="supported_environments">Supported Environments</a></h1>
 115 <p>Perl5.004 builds out of the box on Unix, Plan 9, LynxOS, VMS, OS/2,
 116 QNX, AmigaOS, and Windows NT.  Perl runs on Windows 95 as well, but it
 117 cannot be built there, for lack of a reasonable command interpreter.</p>
 118 <p>
 119 </p>
 120 <hr />
 121 <h1><a name="core_changes">Core Changes</a></h1>
 122 <p>Most importantly, many bugs were fixed, including several security
 123 problems.  See the <em>Changes</em> file in the distribution for details.</p>
 124 <p>
 125 </p>
 126 <h2><a name="list_assignment_to__env_works">List assignment to %ENV works</a></h2>
 127 <p><a href="file://C|\msysgit\mingw\html/pod/perlvar.html#item__env"><code>%ENV = ()</code></a> and <a href="file://C|\msysgit\mingw\html/pod/perlvar.html#item__env"><code>%ENV = @list</code></a> now work as expected (except on VMS
 128 where it generates a fatal error).</p>
 129 <p>
 130 </p>
 131 <h2><a name="change_to_can_t_locate_foo_pm_in__inc_error">Change to ``Can't locate Foo.pm in @INC'' error</a></h2>
 132 <p>The error ``Can't locate Foo.pm in @INC'' now lists the contents of @INC
 133 for easier debugging.</p>
 134 <p>
 135 </p>
 136 <h2><a name="compilation_option__binary_compatibility_with_5_003">Compilation option: Binary compatibility with 5.003</a></h2>
 137 <p>There is a new Configure question that asks if you want to maintain
 138 binary compatibility with Perl 5.003.  If you choose binary
 139 compatibility, you do not have to recompile your extensions, but you
 140 might have symbol conflicts if you embed Perl in another application,
 141 just as in the 5.003 release.  By default, binary compatibility
 142 is preserved at the expense of symbol table pollution.</p>
 143 <p>
 144 </p>
 145 <h2><a name="_perl5opt_environment_variable">$PERL5OPT environment variable</a></h2>
 146 <p>You may now put Perl options in the $PERL5OPT environment variable.
 147 Unless Perl is running with taint checks, it will interpret this
 148 variable as if its contents had appeared on a ``#!perl'' line at the
 149 beginning of your script, except that hyphens are optional.  PERL5OPT
 150 may only be used to set the following switches: <strong>-[DIMUdmw]</strong>.</p>
 151 <p>
 152 </p>
 153 <h2><a name="limitations_on_m__m__and_t_options">Limitations on <strong>-M</strong>, <strong>-m</strong>, and <strong>-T</strong> options</a></h2>
 154 <p>The <code>-M</code> and <code>-m</code> options are no longer allowed on the <code>#!</code> line of
 155 a script.  If a script needs a module, it should invoke it with the
 156 <a href="#item_use"><code>use</code></a> pragma.</p>
 157 <p>The <strong>-T</strong> option is also forbidden on the <code>#!</code> line of a script,
 158 unless it was present on the Perl command line.  Due to the way <code>#!</code>
 159 works, this usually means that <strong>-T</strong> must be in the first argument.
 160 Thus:</p>
 161 <pre>
 162     #!/usr/bin/perl -T -w</pre>
 163 <p>will probably work for an executable script invoked as <code>scriptname</code>,
 164 while:</p>
 165 <pre>
 166     #!/usr/bin/perl -w -T</pre>
 167 <p>will probably fail under the same conditions.  (Non-Unix systems will
 168 probably not follow this rule.)  But <code>perl scriptname</code> is guaranteed
 169 to fail, since then there is no chance of <strong>-T</strong> being found on the
 170 command line before it is found on the <code>#!</code> line.</p>
 171 <p>
 172 </p>
 173 <h2><a name="more_precise_warnings">More precise warnings</a></h2>
 174 <p>If you removed the <strong>-w</strong> option from your Perl 5.003 scripts because it
 175 made Perl too verbose, we recommend that you try putting it back when
 176 you upgrade to Perl 5.004.  Each new perl version tends to remove some
 177 undesirable warnings, while adding new warnings that may catch bugs in
 178 your scripts.</p>
 179 <p>
 180 </p>
 181 <h2><a name="deprecated__inherited_autoload_for_nonmethods">Deprecated: Inherited <code>AUTOLOAD</code> for non-methods</a></h2>
 182 <p>Before Perl 5.004, <code>AUTOLOAD</code> functions were looked up as methods
 183 (using the <code>@ISA</code> hierarchy), even when the function to be autoloaded
 184 was called as a plain function (e.g. <code>Foo::bar()</code>), not a method
 185 (e.g. <code>Foo-&gt;bar()</code> or <code>$obj-&gt;bar()</code>).</p>
 186 <p>Perl 5.005 will use method lookup only for methods' <code>AUTOLOAD</code>s.
 187 However, there is a significant base of existing code that may be using
 188 the old behavior.  So, as an interim step, Perl 5.004 issues an optional
 189 warning when a non-method uses an inherited <code>AUTOLOAD</code>.</p>
 190 <p>The simple rule is:  Inheritance will not work when autoloading
 191 non-methods.  The simple fix for old code is:  In any module that used to
 192 depend on inheriting <code>AUTOLOAD</code> for non-methods from a base class named
 193 <code>BaseClass</code>, execute <code>*AUTOLOAD = \&amp;BaseClass::AUTOLOAD</code> during startup.</p>
 194 <p>
 195 </p>
 196 <h2><a name="previously_deprecated__overload_is_no_longer_usable">Previously deprecated %OVERLOAD is no longer usable</a></h2>
 197 <p>Using %OVERLOAD to define overloading was deprecated in 5.003.
 198 Overloading is now defined using the overload pragma. %OVERLOAD is
 199 still used internally but should not be used by Perl scripts. See
 200 <a href="file://C|\msysgit\mingw\html/lib/overload.html">the overload manpage</a> for more details.</p>
 201 <p>
 202 </p>
 203 <h2><a name="subroutine_arguments_created_only_when_they_re_modified">Subroutine arguments created only when they're modified</a></h2>
 204 <p>In Perl 5.004, nonexistent array and hash elements used as subroutine
 205 parameters are brought into existence only if they are actually
 206 assigned to (via <a href="file://C|\msysgit\mingw\html/pod/perlvar.html#item___"><code>@_</code></a>).</p>
 207 <p>Earlier versions of Perl vary in their handling of such arguments.
 208 Perl versions 5.002 and 5.003 always brought them into existence.
 209 Perl versions 5.000 and 5.001 brought them into existence only if
 210 they were not the first argument (which was almost certainly a bug).
 211 Earlier versions of Perl never brought them into existence.</p>
 212 <p>For example, given this code:</p>
 213 <pre>
 214      undef @a; undef %a;
 215      sub show { print $_[0] };
 216      sub change { $_[0]++ };
 217      show($a[2]);
 218      change($a{b});</pre>
 219 <p>After this code executes in Perl 5.004, $a{b} exists but $a[2] does
 220 not.  In Perl 5.002 and 5.003, both $a{b} and $a[2] would have existed
 221 (but $a[2]'s value would have been undefined).</p>
 222 <p>
 223 </p>
 224 <h2><a name="group_vector_changeable_with___">Group vector changeable with <a href="file://C|\msysgit\mingw\html/pod/perlvar.html#item___"><code>$)</code></a></a></h2>
 225 <p>The <a href="file://C|\msysgit\mingw\html/pod/perlvar.html#item___"><code>$)</code></a> special variable has always (well, in Perl 5, at least)
 226 reflected not only the current effective group, but also the group list
 227 as returned by the <code>getgroups()</code> C function (if there is one).
 228 However, until this release, there has not been a way to call the
 229 <code>setgroups()</code> C function from Perl.</p>
 230 <p>In Perl 5.004, assigning to <a href="file://C|\msysgit\mingw\html/pod/perlvar.html#item___"><code>$)</code></a> is exactly symmetrical with examining
 231 it: The first number in its string value is used as the effective gid;
 232 if there are any numbers after the first one, they are passed to the
 233 <code>setgroups()</code> C function (if there is one).</p>
 234 <p>
 235 </p>
 236 <h2><a name="fixed_parsing_of____digit______digit___etc_">Fixed parsing of $$&lt;digit&gt;, &amp;$&lt;digit&gt;, etc.</a></h2>
 237 <p>Perl versions before 5.004 misinterpreted any type marker followed by
 238 ``$'' and a digit.  For example, ``$$0'' was incorrectly taken to mean
 239 ``${$}0'' instead of ``${$0}''.  This bug is (mostly) fixed in Perl 5.004.</p>
 240 <p>However, the developers of Perl 5.004 could not fix this bug completely,
 241 because at least two widely-used modules depend on the old meaning of
 242 ``$$0'' in a string.  So Perl 5.004 still interprets ``$$&lt;digit&gt;'' in the
 243 old (broken) way inside strings; but it generates this message as a
 244 warning.  And in Perl 5.005, this special treatment will cease.</p>
 245 <p>
 246 </p>
 247 <h2><a name="fixed_localization_of___digit_______etc_">Fixed localization of $&lt;digit&gt;, $&amp;, etc.</a></h2>
 248 <p>Perl versions before 5.004 did not always properly localize the
 249 regex-related special variables.  Perl 5.004 does localize them, as
 250 the documentation has always said it should.  This may result in $1,
 251 $2, etc. no longer being set where existing programs use them.</p>
 252 <p>
 253 </p>
 254 <h2><a name="no_resetting_of____on_implicit_close">No resetting of $. on implicit close</a></h2>
 255 <p>The documentation for Perl 5.0 has always stated that <a href="file://C|\msysgit\mingw\html/pod/perlvar.html#item___"><code>$.</code></a> is <em>not</em>
 256 reset when an already-open file handle is reopened with no intervening
 257 call to <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_close"><code>close</code></a>.  Due to a bug, perl versions 5.000 through 5.003
 258 <em>did</em> reset <a href="file://C|\msysgit\mingw\html/pod/perlvar.html#item___"><code>$.</code></a> under that circumstance; Perl 5.004 does not.</p>
 259 <p>
 260 </p>
 261 <h2><a name="wantarray_may_return_undef"><code>wantarray</code> may return undef</a></h2>
 262 <p>The <code>wantarray</code> operator returns true if a subroutine is expected to
 263 return a list, and false otherwise.  In Perl 5.004, <code>wantarray</code> can
 264 also return the undefined value if a subroutine's return value will
 265 not be used at all, which allows subroutines to avoid a time-consuming
 266 calculation of a return value if it isn't going to be used.</p>
 267 <p>
 268 </p>
 269 <h2><a name="eval_expr_determines_value_of_expr_in_scalar_context"><a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_eval"><code>eval EXPR</code></a> determines value of EXPR in scalar context</a></h2>
 270 <p>Perl (version 5) used to determine the value of EXPR inconsistently,
 271 sometimes incorrectly using the surrounding context for the determination.
 272 Now, the value of EXPR (before being parsed by eval) is always determined in
 273 a scalar context.  Once parsed, it is executed as before, by providing
 274 the context that the scope surrounding the eval provided.  This change
 275 makes the behavior Perl4 compatible, besides fixing bugs resulting from
 276 the inconsistent behavior.  This program:</p>
 277 <pre>
 278     @a = qw(time now is time);
 279     print eval @a;
 280     print '|', scalar eval @a;</pre>
 281 <p>used to print something like ``timenowis881399109|4'', but now (and in perl4)
 282 prints ``4|4''.</p>
 283 <p>
 284 </p>
 285 <h2><a name="changes_to_tainting_checks">Changes to tainting checks</a></h2>
 286 <p>A bug in previous versions may have failed to detect some insecure
 287 conditions when taint checks are turned on.  (Taint checks are used
 288 in setuid or setgid scripts, or when explicitly turned on with the
 289 <code>-T</code> invocation option.)  Although it's unlikely, this may cause a
 290 previously-working script to now fail -- which should be construed
 291 as a blessing, since that indicates a potentially-serious security
 292 hole was just plugged.</p>
 293 <p>The new restrictions when tainting include:</p>
 294 <dl>
 295 <dt><strong><a name="item_glob">No <code>glob()</code> or &lt;*&gt;</a></strong>
 296
 297 <dd>
 298 <p>These operators may spawn the C shell (csh), which cannot be made
 299 safe.  This restriction will be lifted in a future version of Perl
 300 when globbing is implemented without the use of an external program.</p>
 301 </dd>
 302 </li>
 303 <dt><strong><a name="item_no_spawning_if_tainted__24cdpath_2c__24env_2c__24b">No spawning if tainted $CDPATH, $ENV, $BASH_ENV</a></strong>
 304
 305 <dd>
 306 <p>These environment variables may alter the behavior of spawned programs
 307 (especially shells) in ways that subvert security.  So now they are
 308 treated as dangerous, in the manner of $IFS and $PATH.</p>
 309 </dd>
 310 </li>
 311 <dt><strong><a name="item_no_spawning_if_tainted__24term_doesn_27t_look_like">No spawning if tainted $TERM doesn't look like a terminal name</a></strong>
 312
 313 <dd>
 314 <p>Some termcap libraries do unsafe things with $TERM.  However, it would be
 315 unnecessarily harsh to treat all $TERM values as unsafe, since only shell
 316 metacharacters can cause trouble in $TERM.  So a tainted $TERM is
 317 considered to be safe if it contains only alphanumerics, underscores,
 318 dashes, and colons, and unsafe if it contains other characters (including
 319 whitespace).</p>
 320 </dd>
 321 </li>
 322 </dl>
 323 <p>
 324 </p>
 325 <h2><a name="new_opcode_module_and_revised_safe_module">New Opcode module and revised Safe module</a></h2>
 326 <p>A new Opcode module supports the creation, manipulation and
 327 application of opcode masks.  The revised Safe module has a new API
 328 and is implemented using the new Opcode module.  Please read the new
 329 Opcode and Safe documentation.</p>
 330 <p>
 331 </p>
 332 <h2><a name="embedding_improvements">Embedding improvements</a></h2>
 333 <p>In older versions of Perl it was not possible to create more than one
 334 Perl interpreter instance inside a single process without leaking like a
 335 sieve and/or crashing.  The bugs that caused this behavior have all been
 336 fixed.  However, you still must take care when embedding Perl in a C
 337 program.  See the updated perlembed manpage for tips on how to manage
 338 your interpreters.</p>
 339 <p>
 340 </p>
 341 <h2><a name="internal_change__filehandle_class_based_on_io____classes">Internal change: FileHandle class based on IO::* classes</a></h2>
 342 <p>File handles are now stored internally as type IO::Handle.  The
 343 FileHandle module is still supported for backwards compatibility, but
 344 it is now merely a front end to the IO::* modules -- specifically,
 345 IO::Handle, IO::Seekable, and IO::File.  We suggest, but do not
 346 require, that you use the IO::* modules in new code.</p>
 347 <p>In harmony with this change, <code>*GLOB{FILEHANDLE}</code> is now just a
 348 backward-compatible synonym for <code>*GLOB{IO}</code>.</p>
 349 <p>
 350 </p>
 351 <h2><a name="internal_change__perlio_abstraction_interface">Internal change: PerlIO abstraction interface</a></h2>
 352 <p>It is now possible to build Perl with AT&amp;T's sfio IO package
 353 instead of stdio.  See <a href="file://C|\msysgit\mingw\html/pod/perlapio.html">the perlapio manpage</a> for more details, and
 354 the <em>INSTALL</em> file for how to use it.</p>
 355 <p>
 356 </p>
 357 <h2><a name="new_and_changed_syntax">New and changed syntax</a></h2>
 358 <dl>
 359 <dt><strong><a name="item__coderef__params_">$coderef-&gt;(PARAMS)</a></strong>
 360
 361 <dd>
 362 <p>A subroutine reference may now be suffixed with an arrow and a
 363 (possibly empty) parameter list.  This syntax denotes a call of the
 364 referenced subroutine, with the given parameters (if any).</p>
 365 </dd>
 366 <dd>
 367 <p>This new syntax follows the pattern of <code>$hashref-&gt;{FOO}</code> and
 368 <code>$aryref-&gt;[$foo]</code>: You may now write <code>&amp;$subref($foo)</code> as
 369 <code>$subref-&gt;($foo)</code>.  All these arrow terms may be chained;
 370 thus, <code>&amp;{$table-&gt;{FOO}}($bar)</code> may now be written
 371 <code>$table-&gt;{FOO}-&gt;($bar)</code>.</p>
 372 </dd>
 373 </li>
 374 </dl>
 375 <p>
 376 </p>
 377 <h2><a name="new_and_changed_builtin_constants">New and changed builtin constants</a></h2>
 378 <dl>
 379 <dt><strong><a name="item___package__">__PACKAGE__</a></strong>
 380
 381 <dd>
 382 <p>The current package name at compile time, or the undefined value if
 383 there is no current package (due to a <code>package;</code> directive).  Like
 384 <code>__FILE__</code> and <code>__LINE__</code>, <a href="#item___package__"><code>__PACKAGE__</code></a> does <em>not</em> interpolate
 385 into strings.</p>
 386 </dd>
 387 </li>
 388 </dl>
 389 <p>
 390 </p>
 391 <h2><a name="new_and_changed_builtin_variables">New and changed builtin variables</a></h2>
 392 <dl>
 393 <dt><strong><a name="item___e">$^E</a></strong>
 394
 395 <dd>
 396 <p>Extended error message on some platforms.  (Also known as
 397 $EXTENDED_OS_ERROR if you <code>use English</code>).</p>
 398 </dd>
 399 </li>
 400 <dt><strong><a name="item___h">$^H</a></strong>
 401
 402 <dd>
 403 <p>The current set of syntax checks enabled by <code>use strict</code>.  See the
 404 documentation of <code>strict</code> for more details.  Not actually new, but
 405 newly documented.
 406 Because it is intended for internal use by Perl core components,
 407 there is no <code>use English</code> long name for this variable.</p>
 408 </dd>
 409 </li>
 410 <dt><strong><a name="item___m">$^M</a></strong>
 411
 412 <dd>
 413 <p>By default, running out of memory it is not trappable.  However, if
 414 compiled for this, Perl may use the contents of <a href="#item___m"><code>$^M</code></a> as an emergency
 415 pool after die()ing with this message.  Suppose that your Perl were
 416 compiled with -DPERL_EMERGENCY_SBRK and used Perl's malloc.  Then</p>
 417 </dd>
 418 <dd>
 419 <pre>
 420     $^M = 'a' x (1&lt;&lt;16);</pre>
 421 </dd>
 422 <dd>
 423 <p>would allocate a 64K buffer for use when in emergency.
 424 See the <em>INSTALL</em> file for information on how to enable this option.
 425 As a disincentive to casual use of this advanced feature,
 426 there is no <code>use English</code> long name for this variable.</p>
 427 </dd>
 428 </li>
 429 </dl>
 430 <p>
 431 </p>
 432 <h2><a name="new_and_changed_builtin_functions">New and changed builtin functions</a></h2>
 433 <dl>
 434 <dt><strong><a name="item_delete_on_slices">delete on slices</a></strong>
 435
 436 <dd>
 437 <p>This now works.  (e.g. <code>delete @ENV{'PATH', 'MANPATH'}</code>)</p>
 438 </dd>
 439 </li>
 440 <dt><strong><a name="item_flock">flock</a></strong>
 441
 442 <dd>
 443 <p>is now supported on more platforms, prefers fcntl to lockf when
 444 emulating, and always flushes before (un)locking.</p>
 445 </dd>
 446 </li>
 447 <dt><strong><a name="item_printf_and_sprintf">printf and sprintf</a></strong>
 448
 449 <dd>
 450 <p>Perl now implements these functions itself; it doesn't use the C
 451 library function <code>sprintf()</code> any more, except for floating-point
 452 numbers, and even then only known flags are allowed.  As a result, it
 453 is now possible to know which conversions and flags will work, and
 454 what they will do.</p>
 455 </dd>
 456 <dd>
 457 <p>The new conversions in Perl's <code>sprintf()</code> are:</p>
 458 </dd>
 459 <dd>
 460 <pre>
 461    %i   a synonym for %d
 462    %p   a pointer (the address of the Perl value, in hexadecimal)
 463    %n   special: *stores* the number of characters output so far
 464         into the next variable in the parameter list</pre>
 465 </dd>
 466 <dd>
 467 <p>The new flags that go between the <code>%</code> and the conversion are:</p>
 468 </dd>
 469 <dd>
 470 <pre>
 471    #    prefix octal with &quot;0&quot;, hex with &quot;0x&quot;
 472    h    interpret integer as C type &quot;short&quot; or &quot;unsigned short&quot;
 473    V    interpret integer as Perl's standard integer type</pre>
 474 </dd>
 475 <dd>
 476 <p>Also, where a number would appear in the flags, an asterisk (``*'') may
 477 be used instead, in which case Perl uses the next item in the
 478 parameter list as the given number (that is, as the field width or
 479 precision).  If a field width obtained through ``*'' is negative, it has
 480 the same effect as the '-' flag: left-justification.</p>
 481 </dd>
 482 <dd>
 483 <p>See <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#sprintf">sprintf in the perlfunc manpage</a> for a complete list of conversion and flags.</p>
 484 </dd>
 485 </li>
 486 <dt><strong><a name="item_keys_as_an_lvalue">keys as an lvalue</a></strong>
 487
 488 <dd>
 489 <p>As an lvalue, <code>keys</code> allows you to increase the number of hash buckets
 490 allocated for the given hash.  This can gain you a measure of efficiency if
 491 you know the hash is going to get big.  (This is similar to pre-extending
 492 an array by assigning a larger number to $#array.)  If you say</p>
 493 </dd>
 494 <dd>
 495 <pre>
 496     keys %hash = 200;</pre>
 497 </dd>
 498 <dd>
 499 <p>then <code>%hash</code> will have at least 200 buckets allocated for it.  These
 500 buckets will be retained even if you do <code>%hash = ()</code>; use <code>undef
 501 %hash</code> if you want to free the storage while <code>%hash</code> is still in scope.
 502 You can't shrink the number of buckets allocated for the hash using
 503 <code>keys</code> in this way (but you needn't worry about doing this by accident,
 504 as trying has no effect).</p>
 505 </dd>
 506 </li>
 507 <dt><strong><a name="item_my"><code>my()</code> in Control Structures</a></strong>
 508
 509 <dd>
 510 <p>You can now use <a href="#item_my"><code>my()</code></a> (with or without the parentheses) in the control
 511 expressions of control structures such as:</p>
 512 </dd>
 513 <dd>
 514 <pre>
 515     while (defined(my $line = &lt;&gt;)) {
 516         $line = lc $line;
 517     } continue {
 518         print $line;
 519     }</pre>
 520 </dd>
 521 <dd>
 522 <pre>
 523     if ((my $answer = &lt;STDIN&gt;) =~ /^y(es)?$/i) {
 524         user_agrees();
 525     } elsif ($answer =~ /^n(o)?$/i) {
 526         user_disagrees();
 527     } else {
 528         chomp $answer;
 529         die &quot;`$answer' is neither `yes' nor `no'&quot;;
 530     }</pre>
 531 </dd>
 532 <dd>
 533 <p>Also, you can declare a foreach loop control variable as lexical by
 534 preceding it with the word ``my''.  For example, in:</p>
 535 </dd>
 536 <dd>
 537 <pre>
 538     foreach my $i (1, 2, 3) {
 539         some_function();
 540     }</pre>
 541 </dd>
 542 <dd>
 543 <p>$i is a lexical variable, and the scope of $i extends to the end of
 544 the loop, but not beyond it.</p>
 545 </dd>
 546 <dd>
 547 <p>Note that you still cannot use <a href="#item_my"><code>my()</code></a> on global punctuation variables
 548 such as $_ and the like.</p>
 549 </dd>
 550 </li>
 551 <dt><strong><a name="item_pack"><code>pack()</code> and <code>unpack()</code></a></strong>
 552
 553 <dd>
 554 <p>A new format 'w' represents a BER compressed integer (as defined in
 555 ASN.1).  Its format is a sequence of one or more bytes, each of which
 556 provides seven bits of the total value, with the most significant
 557 first.  Bit eight of each byte is set, except for the last byte, in
 558 which bit eight is clear.</p>
 559 </dd>
 560 <dd>
 561 <p>If 'p' or 'P' are given undef as values, they now generate a NULL
 562 pointer.</p>
 563 </dd>
 564 <dd>
 565 <p>Both <a href="#item_pack"><code>pack()</code></a> and <code>unpack()</code> now fail when their templates contain invalid
 566 types.  (Invalid types used to be ignored.)</p>
 567 </dd>
 568 </li>
 569 <dt><strong><a name="item_sysseek"><code>sysseek()</code></a></strong>
 570
 571 <dd>
 572 <p>The new <a href="#item_sysseek"><code>sysseek()</code></a> operator is a variant of <code>seek()</code> that sets and gets the
 573 file's system read/write position, using the <code>lseek(2)</code> system call.  It is
 574 the only reliable way to seek before using <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_sysread"><code>sysread()</code></a> or syswrite().  Its
 575 return value is the new position, or the undefined value on failure.</p>
 576 </dd>
 577 </li>
 578 <dt><strong><a name="item_use">use VERSION</a></strong>
 579
 580 <dd>
 581 <p>If the first argument to <a href="#item_use"><code>use</code></a> is a number, it is treated as a version
 582 number instead of a module name.  If the version of the Perl interpreter
 583 is less than VERSION, then an error message is printed and Perl exits
 584 immediately.  Because <a href="#item_use"><code>use</code></a> occurs at compile time, this check happens
 585 immediately during the compilation process, unlike <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_require"><code>require VERSION</code></a>,
 586 which waits until runtime for the check.  This is often useful if you
 587 need to check the current Perl version before <a href="#item_use"><code>use</code></a>ing library modules
 588 which have changed in incompatible ways from older versions of Perl.
 589 (We try not to do this more than we have to.)</p>
 590 </dd>
 591 </li>
 592 <dt><strong>use Module VERSION LIST</strong>
 593
 594 <dd>
 595 <p>If the VERSION argument is present between Module and LIST, then the
 596 <a href="#item_use"><code>use</code></a> will call the VERSION method in class Module with the given
 597 version as an argument.  The default VERSION method, inherited from
 598 the UNIVERSAL class, croaks if the given version is larger than the
 599 value of the variable $Module::VERSION.  (Note that there is not a
 600 comma after VERSION!)</p>
 601 </dd>
 602 <dd>
 603 <p>This version-checking mechanism is similar to the one currently used
 604 in the Exporter module, but it is faster and can be used with modules
 605 that don't use the Exporter.  It is the recommended method for new
 606 code.</p>
 607 </dd>
 608 </li>
 609 <dt><strong><a name="item_prototype"><code>prototype(FUNCTION)</code></a></strong>
 610
 611 <dd>
 612 <p>Returns the prototype of a function as a string (or <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_undef"><code>undef</code></a> if the
 613 function has no prototype).  FUNCTION is a reference to or the name of the
 614 function whose prototype you want to retrieve.
 615 (Not actually new; just never documented before.)</p>
 616 </dd>
 617 </li>
 618 <dt><strong><a name="item_srand">srand</a></strong>
 619
 620 <dd>
 621 <p>The default seed for <a href="#item_srand"><code>srand</code></a>, which used to be <code>time</code>, has been changed.
 622 Now it's a heady mix of difficult-to-predict system-dependent values,
 623 which should be sufficient for most everyday purposes.</p>
 624 </dd>
 625 <dd>
 626 <p>Previous to version 5.004, calling <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_rand"><code>rand</code></a> without first calling <a href="#item_srand"><code>srand</code></a>
 627 would yield the same sequence of random numbers on most or all machines.
 628 Now, when perl sees that you're calling <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_rand"><code>rand</code></a> and haven't yet called
 629 <a href="#item_srand"><code>srand</code></a>, it calls <a href="#item_srand"><code>srand</code></a> with the default seed. You should still call
 630 <a href="#item_srand"><code>srand</code></a> manually if your code might ever be run on a pre-5.004 system,
 631 of course, or if you want a seed other than the default.</p>
 632 </dd>
 633 </li>
 634 <dt><strong><a name="item___">$_ as Default</a></strong>
 635
 636 <dd>
 637 <p>Functions documented in the Camel to default to $_ now in
 638 fact do, and all those that do are so documented in <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html">the perlfunc manpage</a>.</p>
 639 </dd>
 640 </li>
 641 <dt><strong><a name="item_m_2f_2fgc_does_not_reset_search_position_on_failur"><a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_m_"><code>m//gc</code></a> does not reset search position on failure</a></strong>
 642
 643 <dd>
 644 <p>The <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_m_"><code>m//g</code></a> match iteration construct has always reset its target
 645 string's search position (which is visible through the <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_pos"><code>pos</code></a> operator)
 646 when a match fails; as a result, the next <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_m_"><code>m//g</code></a> match after a failure
 647 starts again at the beginning of the string.  With Perl 5.004, this
 648 reset may be disabled by adding the ``c'' (for ``continue'') modifier,
 649 i.e. <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_m_"><code>m//gc</code></a>.  This feature, in conjunction with the <code>\G</code> zero-width
 650 assertion, makes it possible to chain matches together.  See <a href="file://C|\msysgit\mingw\html/pod/perlop.html">the perlop manpage</a>
 651 and <a href="file://C|\msysgit\mingw\html/pod/perlre.html">the perlre manpage</a>.</p>
 652 </dd>
 653 </li>
 654 <dt><strong><a name="item_m_2f_2fx_ignores_whitespace_before__3f_2a_2b_7b_7d"><a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_m_"><code>m//x</code></a> ignores whitespace before ?*+{}</a></strong>
 655
 656 <dd>
 657 <p>The <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_m_"><code>m//x</code></a> construct has always been intended to ignore all unescaped
 658 whitespace.  However, before Perl 5.004, whitespace had the effect of
 659 escaping repeat modifiers like ``*'' or ``?''; for example, <code>/a *b/x</code> was
 660 (mis)interpreted as <code>/a\*b/x</code>.  This bug has been fixed in 5.004.</p>
 661 </dd>
 662 </li>
 663 <dt><strong><a name="item_nested_sub_7b_7d_closures_work_now">nested <code>sub{}</code> closures work now</a></strong>
 664
 665 <dd>
 666 <p>Prior to the 5.004 release, nested anonymous functions didn't work
 667 right.  They do now.</p>
 668 </dd>
 669 </li>
 670 <dt><strong><a name="item_formats_work_right_on_changing_lexicals">formats work right on changing lexicals</a></strong>
 671
 672 <dd>
 673 <p>Just like anonymous functions that contain lexical variables
 674 that change (like a lexical index variable for a <code>foreach</code> loop),
 675 formats now work properly.  For example, this silently failed
 676 before (printed only zeros), but is fine now:</p>
 677 </dd>
 678 <dd>
 679 <pre>
 680     my $i;
 681     foreach $i ( 1 .. 10 ) {
 682         write;
 683     }
 684     format =
 685         my i is @#
 686         $i
 687     .</pre>
 688 </dd>
 689 <dd>
 690 <p>However, it still fails (without a warning) if the foreach is within a
 691 subroutine:</p>
 692 </dd>
 693 <dd>
 694 <pre>
 695     my $i;
 696     sub foo {
 697       foreach $i ( 1 .. 10 ) {
 698         write;
 699       }
 700     }
 701     foo;
 702     format =
 703         my i is @#
 704         $i
 705     .</pre>
 706 </dd>
 707 </li>
 708 </dl>
 709 <p>
 710 </p>
 711 <h2><a name="new_builtin_methods">New builtin methods</a></h2>
 712 <p>The <code>UNIVERSAL</code> package automatically contains the following methods that
 713 are inherited by all other classes:</p>
 714 <dl>
 715 <dt><strong><a name="item_isa"><code>isa(CLASS)</code></a></strong>
 716
 717 <dd>
 718 <p><a href="#item_isa"><code>isa</code></a> returns <em>true</em> if its object is blessed into a subclass of <code>CLASS</code></p>
 719 </dd>
 720 <dd>
 721 <p><a href="#item_isa"><code>isa</code></a> is also exportable and can be called as a sub with two arguments. This
 722 allows the ability to check what a reference points to. Example:</p>
 723 </dd>
 724 <dd>
 725 <pre>
 726     use UNIVERSAL qw(isa);</pre>
 727 </dd>
 728 <dd>
 729 <pre>
 730     if(isa($ref, 'ARRAY')) {
 731        ...
 732     }</pre>
 733 </dd>
 734 </li>
 735 <dt><strong><a name="item_can"><code>can(METHOD)</code></a></strong>
 736
 737 <dd>
 738 <p><a href="#item_can"><code>can</code></a> checks to see if its object has a method called <code>METHOD</code>,
 739 if it does then a reference to the sub is returned; if it does not then
 740 <em>undef</em> is returned.</p>
 741 </dd>
 742 </li>
 743 <dt><strong><a name="item_version">VERSION( [NEED] )</a></strong>
 744
 745 <dd>
 746 <p><a href="#item_version"><code>VERSION</code></a> returns the version number of the class (package).  If the
 747 NEED argument is given then it will check that the current version (as
 748 defined by the $VERSION variable in the given package) not less than
 749 NEED; it will die if this is not the case.  This method is normally
 750 called as a class method.  This method is called automatically by the
 751 <a href="#item_version"><code>VERSION</code></a> form of <a href="#item_use"><code>use</code></a>.</p>
 752 </dd>
 753 <dd>
 754 <pre>
 755     use A 1.2 qw(some imported subs);
 756     # implies:
 757     A-&gt;VERSION(1.2);</pre>
 758 </dd>
 759 </li>
 760 </dl>
 761 <p><strong>NOTE:</strong> <a href="#item_can"><code>can</code></a> directly uses Perl's internal code for method lookup, and
 762 <a href="#item_isa"><code>isa</code></a> uses a very similar method and caching strategy. This may cause
 763 strange effects if the Perl code dynamically changes @ISA in any package.</p>
 764 <p>You may add other methods to the UNIVERSAL class via Perl or XS code.
 765 You do not need to <a href="#item_use"><code>use UNIVERSAL</code></a> in order to make these methods
 766 available to your program.  This is necessary only if you wish to
 767 have <a href="#item_isa"><code>isa</code></a> available as a plain subroutine in the current package.</p>
 768 <p>
 769 </p>
 770 <h2><a name="tiehandle_now_supported">TIEHANDLE now supported</a></h2>
 771 <p>See <a href="file://C|\msysgit\mingw\html/pod/perltie.html">the perltie manpage</a> for other kinds of tie()s.</p>
 772 <dl>
 773 <dt><strong><a name="item_tiehandle_classname_2c_list">TIEHANDLE classname, LIST</a></strong>
 774
 775 <dd>
 776 <p>This is the constructor for the class.  That means it is expected to
 777 return an object of some sort. The reference can be used to
 778 hold some internal information.</p>
 779 </dd>
 780 <dd>
 781 <pre>
 782     sub TIEHANDLE {
 783         print &quot;&lt;shout&gt;\n&quot;;
 784         my $i;
 785         return bless \$i, shift;
 786     }</pre>
 787 </dd>
 788 </li>
 789 <dt><strong><a name="item_print_this_2c_list">PRINT this, LIST</a></strong>
 790
 791 <dd>
 792 <p>This method will be triggered every time the tied handle is printed to.
 793 Beyond its self reference it also expects the list that was passed to
 794 the print function.</p>
 795 </dd>
 796 <dd>
 797 <pre>
 798     sub PRINT {
 799         $r = shift;
 800         $$r++;
 801         return print join( $, =&gt; map {uc} @_), $\;
 802     }</pre>
 803 </dd>
 804 </li>
 805 <dt><strong><a name="item_printf_this_2c_list">PRINTF this, LIST</a></strong>
 806
 807 <dd>
 808 <p>This method will be triggered every time the tied handle is printed to
 809 with the <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_printf"><code>printf()</code></a> function.
 810 Beyond its self reference it also expects the format and list that was
 811 passed to the printf function.</p>
 812 </dd>
 813 <dd>
 814 <pre>
 815     sub PRINTF {
 816         shift;
 817           my $fmt = shift;
 818         print sprintf($fmt, @_).&quot;\n&quot;;
 819     }</pre>
 820 </dd>
 821 </li>
 822 <dt><strong><a name="item_read_this_list">READ this LIST</a></strong>
 823
 824 <dd>
 825 <p>This method will be called when the handle is read from via the <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_read"><code>read</code></a>
 826 or <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_sysread"><code>sysread</code></a> functions.</p>
 827 </dd>
 828 <dd>
 829 <pre>
 830     sub READ {
 831         $r = shift;
 832         my($buf,$len,$offset) = @_;
 833         print &quot;READ called, \$buf=$buf, \$len=$len, \$offset=$offset&quot;;
 834     }</pre>
 835 </dd>
 836 </li>
 837 <dt><strong><a name="item_readline_this">READLINE this</a></strong>
 838
 839 <dd>
 840 <p>This method will be called when the handle is read from. The method
 841 should return undef when there is no more data.</p>
 842 </dd>
 843 <dd>
 844 <pre>
 845     sub READLINE {
 846         $r = shift;
 847         return &quot;PRINT called $$r times\n&quot;
 848     }</pre>
 849 </dd>
 850 </li>
 851 <dt><strong><a name="item_getc_this">GETC this</a></strong>
 852
 853 <dd>
 854 <p>This method will be called when the <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_getc"><code>getc</code></a> function is called.</p>
 855 </dd>
 856 <dd>
 857 <pre>
 858     sub GETC { print &quot;Don't GETC, Get Perl&quot;; return &quot;a&quot;; }</pre>
 859 </dd>
 860 </li>
 861 <dt><strong><a name="item_destroy_this">DESTROY this</a></strong>
 862
 863 <dd>
 864 <p>As with the other types of ties, this method will be called when the
 865 tied handle is about to be destroyed. This is useful for debugging and
 866 possibly for cleaning up.</p>
 867 </dd>
 868 <dd>
 869 <pre>
 870     sub DESTROY {
 871         print &quot;&lt;/shout&gt;\n&quot;;
 872     }</pre>
 873 </dd>
 874 </li>
 875 </dl>
 876 <p>
 877 </p>
 878 <h2><a name="malloc_enhancements">Malloc enhancements</a></h2>
 879 <p>If perl is compiled with the malloc included with the perl distribution
 880 (that is, if <code>perl -V:d_mymalloc</code> is 'define') then you can print
 881 memory statistics at runtime by running Perl thusly:</p>
 882 <pre>
 883   env PERL_DEBUG_MSTATS=2 perl your_script_here</pre>
 884 <p>The value of 2 means to print statistics after compilation and on
 885 exit; with a value of 1, the statistics are printed only on exit.
 886 (If you want the statistics at an arbitrary time, you'll need to
 887 install the optional module Devel::Peek.)</p>
 888 <p>Three new compilation flags are recognized by malloc.c.  (They have no
 889 effect if perl is compiled with system <code>malloc().)</code></p>
 890 <dl>
 891 <dt><strong><a name="item__2ddperl_emergency_sbrk">-DPERL_EMERGENCY_SBRK</a></strong>
 892
 893 <dd>
 894 <p>If this macro is defined, running out of memory need not be a fatal
 895 error: a memory pool can allocated by assigning to the special
 896 variable <a href="#item___m"><code>$^M</code></a>.  See <a href="#item___m">$^M</a>.</p>
 897 </dd>
 898 </li>
 899 <dt><strong><a name="item__2ddpack_malloc">-DPACK_MALLOC</a></strong>
 900
 901 <dd>
 902 <p>Perl memory allocation is by bucket with sizes close to powers of two.
 903 Because of these malloc overhead may be big, especially for data of
 904 size exactly a power of two.  If <code>PACK_MALLOC</code> is defined, perl uses
 905 a slightly different algorithm for small allocations (up to 64 bytes
 906 long), which makes it possible to have overhead down to 1 byte for
 907 allocations which are powers of two (and appear quite often).</p>
 908 </dd>
 909 <dd>
 910 <p>Expected memory savings (with 8-byte alignment in <code>alignbytes</code>) is
 911 about 20% for typical Perl usage.  Expected slowdown due to additional
 912 malloc overhead is in fractions of a percent (hard to measure, because
 913 of the effect of saved memory on speed).</p>
 914 </dd>
 915 </li>
 916 <dt><strong><a name="item__2ddtwo_pot_optimize">-DTWO_POT_OPTIMIZE</a></strong>
 917
 918 <dd>
 919 <p>Similarly to <code>PACK_MALLOC</code>, this macro improves allocations of data
 920 with size close to a power of two; but this works for big allocations
 921 (starting with 16K by default).  Such allocations are typical for big
 922 hashes and special-purpose scripts, especially image processing.</p>
 923 </dd>
 924 <dd>
 925 <p>On recent systems, the fact that perl requires 2M from system for 1M
 926 allocation will not affect speed of execution, since the tail of such
 927 a chunk is not going to be touched (and thus will not require real
 928 memory).  However, it may result in a premature out-of-memory error.
 929 So if you will be manipulating very large blocks with sizes close to
 930 powers of two, it would be wise to define this macro.</p>
 931 </dd>
 932 <dd>
 933 <p>Expected saving of memory is 0-100% (100% in applications which
 934 require most memory in such 2**n chunks); expected slowdown is
 935 negligible.</p>
 936 </dd>
 937 </li>
 938 </dl>
 939 <p>
 940 </p>
 941 <h2><a name="miscellaneous_efficiency_enhancements">Miscellaneous efficiency enhancements</a></h2>
 942 <p>Functions that have an empty prototype and that do nothing but return
 943 a fixed value are now inlined (e.g. <code>sub PI () { 3.14159 }</code>).</p>
 944 <p>Each unique hash key is only allocated once, no matter how many hashes
 945 have an entry with that key.  So even if you have 100 copies of the
 946 same hash, the hash keys never have to be reallocated.</p>
 947 <p>
 948 </p>
 949 <hr />
 950 <h1><a name="support_for_more_operating_systems">Support for More Operating Systems</a></h1>
 951 <p>Support for the following operating systems is new in Perl 5.004.</p>
 952 <p>
 953 </p>
 954 <h2><a name="win32">Win32</a></h2>
 955 <p>Perl 5.004 now includes support for building a ``native'' perl under
 956 Windows NT, using the Microsoft Visual C++ compiler (versions 2.0
 957 and above) or the Borland C++ compiler (versions 5.02 and above).
 958 The resulting perl can be used under Windows 95 (if it
 959 is installed in the same directory locations as it got installed
 960 in Windows NT).  This port includes support for perl extension
 961 building tools like <a href="file://C|\msysgit\mingw\html/lib/ExtUtils/MakeMaker.html">the MakeMaker manpage</a> and <a href="file://C|\msysgit\mingw\html/utils/h2xs.html">the h2xs manpage</a>, so that many extensions
 962 available on the Comprehensive Perl Archive Network (CPAN) can now be
 963 readily built under Windows NT.  See <a href="http://www.perl.com/">http://www.perl.com/</a> for more
 964 information on CPAN and <em>README.win32</em> in the perl distribution for more
 965 details on how to get started with building this port.</p>
 966 <p>There is also support for building perl under the Cygwin32 environment.
 967 Cygwin32 is a set of GNU tools that make it possible to compile and run
 968 many Unix programs under Windows NT by providing a mostly Unix-like
 969 interface for compilation and execution.  See <em>README.cygwin32</em> in the
 970 perl distribution for more details on this port and how to obtain the
 971 Cygwin32 toolkit.</p>
 972 <p>
 973 </p>
 974 <h2><a name="plan_9">Plan 9</a></h2>
 975 <p>See <em>README.plan9</em> in the perl distribution.</p>
 976 <p>
 977 </p>
 978 <h2><a name="qnx">QNX</a></h2>
 979 <p>See <em>README.qnx</em> in the perl distribution.</p>
 980 <p>
 981 </p>
 982 <h2><a name="amigaos">AmigaOS</a></h2>
 983 <p>See <em>README.amigaos</em> in the perl distribution.</p>
 984 <p>
 985 </p>
 986 <hr />
 987 <h1><a name="pragmata">Pragmata</a></h1>
 988 <p>Six new pragmatic modules exist:</p>
 989 <dl>
 990 <dt><strong><a name="item_qw">use autouse MODULE =&gt; qw(sub1 sub2 sub3)</a></strong>
 991
 992 <dd>
 993 <p>Defers <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_require"><code>require MODULE</code></a> until someone calls one of the specified
 994 subroutines (which must be exported by MODULE).  This pragma should be
 995 used with caution, and only when necessary.</p>
 996 </dd>
 997 </li>
 998 <dt><strong><a name="item_use_blib">use blib</a></strong>
 999
1000 <dt><strong><a name="item_use_blib__27dir_27">use blib 'dir'</a></strong>
1001
1002 <dd>
1003 <p>Looks for MakeMaker-like <em>'blib'</em> directory structure starting in
1004 <em>dir</em> (or current directory) and working back up to five levels of
1005 parent directories.</p>
1006 </dd>
1007 <dd>
1008 <p>Intended for use on command line with <strong>-M</strong> option as a way of testing
1009 arbitrary scripts against an uninstalled version of a package.</p>
1010 </dd>
1011 </li>
1012 <dt><strong><a name="item_use_constant_name__3d_3e_value">use constant NAME =&gt; VALUE</a></strong>
1013
1014 <dd>
1015 <p>Provides a convenient interface for creating compile-time constants,
1016 See <a href="file://C|\msysgit\mingw\html/pod/perlsub.html#constant_functions">Constant Functions in the perlsub manpage</a>.</p>
1017 </dd>
1018 </li>
1019 <dt><strong><a name="item_use_locale">use locale</a></strong>
1020
1021 <dd>
1022 <p>Tells the compiler to enable (or disable) the use of POSIX locales for
1023 builtin operations.</p>
1024 </dd>
1025 <dd>
1026 <p>When <a href="#item_use_locale"><code>use locale</code></a> is in effect, the current LC_CTYPE locale is used
1027 for regular expressions and case mapping; LC_COLLATE for string
1028 ordering; and LC_NUMERIC for numeric formatting in printf and sprintf
1029 (but <strong>not</strong> in print).  LC_NUMERIC is always used in write, since
1030 lexical scoping of formats is problematic at best.</p>
1031 </dd>
1032 <dd>
1033 <p>Each <a href="#item_use_locale"><code>use locale</code></a> or <code>no locale</code> affects statements to the end of
1034 the enclosing BLOCK or, if not inside a BLOCK, to the end of the
1035 current file.  Locales can be switched and queried with
1036 POSIX::setlocale().</p>
1037 </dd>
1038 <dd>
1039 <p>See <a href="file://C|\msysgit\mingw\html/pod/perllocale.html">the perllocale manpage</a> for more information.</p>
1040 </dd>
1041 </li>
1042 <dt><strong><a name="item_use_ops">use ops</a></strong>
1043
1044 <dd>
1045 <p>Disable unsafe opcodes, or any named opcodes, when compiling Perl code.</p>
1046 </dd>
1047 </li>
1048 <dt><strong><a name="item_use_vmsish">use vmsish</a></strong>
1049
1050 <dd>
1051 <p>Enable VMS-specific language features.  Currently, there are three
1052 VMS-specific features available: 'status', which makes <a href="file://C|\msysgit\mingw\html/pod/perlvar.html#item__"><code>$?</code></a> and
1053 <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_system"><code>system</code></a> return genuine VMS status values instead of emulating POSIX;
1054 'exit', which makes <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_exit"><code>exit</code></a> take a genuine VMS status value instead of
1055 assuming that <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_exit"><code>exit 1</code></a> is an error; and 'time', which makes all times
1056 relative to the local time zone, in the VMS tradition.</p>
1057 </dd>
1058 </li>
1059 </dl>
1060 <p>
1061 </p>
1062 <hr />
1063 <h1><a name="modules">Modules</a></h1>
1064 <p>
1065 </p>
1066 <h2><a name="required_updates">Required Updates</a></h2>
1067 <p>Though Perl 5.004 is compatible with almost all modules that work
1068 with Perl 5.003, there are a few exceptions:</p>
1069 <pre>
1070     Module   Required Version for Perl 5.004
1071     ------   -------------------------------
1072     Filter   Filter-1.12
1073     LWP      libwww-perl-5.08
1074     Tk       Tk400.202 (-w makes noise)</pre>
1075 <p>Also, the majordomo mailing list program, version 1.94.1, doesn't work
1076 with Perl 5.004 (nor with perl 4), because it executes an invalid
1077 regular expression.  This bug is fixed in majordomo version 1.94.2.</p>
1078 <p>
1079 </p>
1080 <h2><a name="installation_directories">Installation directories</a></h2>
1081 <p>The <em>installperl</em> script now places the Perl source files for
1082 extensions in the architecture-specific library directory, which is
1083 where the shared libraries for extensions have always been.  This
1084 change is intended to allow administrators to keep the Perl 5.004
1085 library directory unchanged from a previous version, without running
1086 the risk of binary incompatibility between extensions' Perl source and
1087 shared libraries.</p>
1088 <p>
1089 </p>
1090 <h2><a name="module_information_summary">Module information summary</a></h2>
1091 <p>Brand new modules, arranged by topic rather than strictly
1092 alphabetically:</p>
1093 <pre>
1094     CGI.pm               Web server interface (&quot;Common Gateway Interface&quot;)
1095     CGI/Apache.pm        Support for Apache's Perl module
1096     CGI/Carp.pm          Log server errors with helpful context
1097     CGI/Fast.pm          Support for FastCGI (persistent server process)
1098     CGI/Push.pm          Support for server push
1099     CGI/Switch.pm        Simple interface for multiple server types</pre>
1100 <pre>
1101     CPAN                 Interface to Comprehensive Perl Archive Network
1102     CPAN::FirstTime      Utility for creating CPAN configuration file
1103     CPAN::Nox            Runs CPAN while avoiding compiled extensions</pre>
1104 <pre>
1105     IO.pm                Top-level interface to IO::* classes
1106     IO/File.pm           IO::File extension Perl module
1107     IO/Handle.pm         IO::Handle extension Perl module
1108     IO/Pipe.pm           IO::Pipe extension Perl module
1109     IO/Seekable.pm       IO::Seekable extension Perl module
1110     IO/Select.pm         IO::Select extension Perl module
1111     IO/Socket.pm         IO::Socket extension Perl module</pre>
1112 <pre>
1113     Opcode.pm            Disable named opcodes when compiling Perl code</pre>
1114 <pre>
1115     ExtUtils/Embed.pm    Utilities for embedding Perl in C programs
1116     ExtUtils/testlib.pm  Fixes up @INC to use just-built extension</pre>
1117 <pre>
1118     FindBin.pm           Find path of currently executing program</pre>
1119 <pre>
1120     Class/Struct.pm      Declare struct-like datatypes as Perl classes
1121     File/stat.pm         By-name interface to Perl's builtin stat
1122     Net/hostent.pm       By-name interface to Perl's builtin gethost*
1123     Net/netent.pm        By-name interface to Perl's builtin getnet*
1124     Net/protoent.pm      By-name interface to Perl's builtin getproto*
1125     Net/servent.pm       By-name interface to Perl's builtin getserv*
1126     Time/gmtime.pm       By-name interface to Perl's builtin gmtime
1127     Time/localtime.pm    By-name interface to Perl's builtin localtime
1128     Time/tm.pm           Internal object for Time::{gm,local}time
1129     User/grent.pm        By-name interface to Perl's builtin getgr*
1130     User/pwent.pm        By-name interface to Perl's builtin getpw*</pre>
1131 <pre>
1132     Tie/RefHash.pm       Base class for tied hashes with references as keys</pre>
1133 <pre>
1134     UNIVERSAL.pm         Base class for *ALL* classes</pre>
1135 <p>
1136 </p>
1137 <h2><a name="fcntl">Fcntl</a></h2>
1138 <p>New constants in the existing Fcntl modules are now supported,
1139 provided that your operating system happens to support them:</p>
1140 <pre>
1141     F_GETOWN F_SETOWN
1142     O_ASYNC O_DEFER O_DSYNC O_FSYNC O_SYNC
1143     O_EXLOCK O_SHLOCK</pre>
1144 <p>These constants are intended for use with the Perl operators <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_sysopen"><code>sysopen()</code></a>
1145 and <code>fcntl()</code> and the basic database modules like SDBM_File.  For the
1146 exact meaning of these and other Fcntl constants please refer to your
1147 operating system's documentation for <code>fcntl()</code> and open().</p>
1148 <p>In addition, the Fcntl module now provides these constants for use
1149 with the Perl operator flock():</p>
1150 <pre>
1151         LOCK_SH LOCK_EX LOCK_NB LOCK_UN</pre>
1152 <p>These constants are defined in all environments (because where there is
1153 no <a href="#item_flock"><code>flock()</code></a> system call, Perl emulates it).  However, for historical
1154 reasons, these constants are not exported unless they are explicitly
1155 requested with the ``:flock'' tag (e.g. <code>use Fcntl ':flock'</code>).</p>
1156 <p>
1157 </p>
1158 <h2><a name="io">IO</a></h2>
1159 <p>The IO module provides a simple mechanism to load all the IO modules at one
1160 go.  Currently this includes:</p>
1161 <pre>
1162      IO::Handle
1163      IO::Seekable
1164      IO::File
1165      IO::Pipe
1166      IO::Socket</pre>
1167 <p>For more information on any of these modules, please see its
1168 respective documentation.</p>
1169 <p>
1170 </p>
1171 <h2><a name="math__complex">Math::Complex</a></h2>
1172 <p>The Math::Complex module has been totally rewritten, and now supports
1173 more operations.  These are overloaded:</p>
1174 <pre>
1175      + - * / ** &lt;=&gt; neg ~ abs sqrt exp log sin cos atan2 &quot;&quot; (stringify)</pre>
1176 <p>And these functions are now exported:</p>
1177 <pre>
1178     pi i Re Im arg
1179     log10 logn ln cbrt root
1180     tan
1181     csc sec cot
1182     asin acos atan
1183     acsc asec acot
1184     sinh cosh tanh
1185     csch sech coth
1186     asinh acosh atanh
1187     acsch asech acoth
1188     cplx cplxe</pre>
1189 <p>
1190 </p>
1191 <h2><a name="math__trig">Math::Trig</a></h2>
1192 <p>This new module provides a simpler interface to parts of Math::Complex for
1193 those who need trigonometric functions only for real numbers.</p>
1194 <p>
1195 </p>
1196 <h2><a name="db_file">DB_File</a></h2>
1197 <p>There have been quite a few changes made to DB_File. Here are a few of
1198 the highlights:</p>
1199 <ul>
1200 <li>
1201 <p>Fixed a handful of bugs.</p>
1202 </li>
1203 <li>
1204 <p>By public demand, added support for the standard hash function exists().</p>
1205 </li>
1206 <li>
1207 <p>Made it compatible with Berkeley DB 1.86.</p>
1208 </li>
1209 <li>
1210 <p>Made negative subscripts work with RECNO interface.</p>
1211 </li>
1212 <li>
1213 <p>Changed the default flags from O_RDWR to O_CREAT|O_RDWR and the default
1214 mode from 0640 to 0666.</p>
1215 </li>
1216 <li>
1217 <p>Made DB_File automatically import the <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_open"><code>open()</code></a> constants (O_RDWR,
1218 O_CREAT etc.) from Fcntl, if available.</p>
1219 </li>
1220 <li>
1221 <p>Updated documentation.</p>
1222 </li>
1223 </ul>
1224 <p>Refer to the HISTORY section in DB_File.pm for a complete list of
1225 changes. Everything after DB_File 1.01 has been added since 5.003.</p>
1226 <p>
1227 </p>
1228 <h2><a name="net__ping">Net::Ping</a></h2>
1229 <p>Major rewrite - support added for both udp echo and real icmp pings.</p>
1230 <p>
1231 </p>
1232 <h2><a name="objectoriented_overrides_for_builtin_operators">Object-oriented overrides for builtin operators</a></h2>
1233 <p>Many of the Perl builtins returning lists now have
1234 object-oriented overrides.  These are:</p>
1235 <pre>
1236     File::stat
1237     Net::hostent
1238     Net::netent
1239     Net::protoent
1240     Net::servent
1241     Time::gmtime
1242     Time::localtime
1243     User::grent
1244     User::pwent</pre>
1245 <p>For example, you can now say</p>
1246 <pre>
1247     use File::stat;
1248     use User::pwent;
1249     $his = (stat($filename)-&gt;st_uid == pwent($whoever)-&gt;pw_uid);</pre>
1250 <p>
1251 </p>
1252 <hr />
1253 <h1><a name="utility_changes">Utility Changes</a></h1>
1254 <p>
1255 </p>
1256 <h2><a name="pod2html">pod2html</a></h2>
1257 <dl>
1258 <dt><strong><a name="item_sends_converted_html_to_standard_output">Sends converted HTML to standard output</a></strong>
1259
1260 <dd>
1261 <p>The <em>pod2html</em> utility included with Perl 5.004 is entirely new.
1262 By default, it sends the converted HTML to its standard output,
1263 instead of writing it to a file like Perl 5.003's <em>pod2html</em> did.
1264 Use the <strong>--outfile=FILENAME</strong> option to write to a file.</p>
1265 </dd>
1266 </li>
1267 </dl>
1268 <p>
1269 </p>
1270 <h2><a name="xsubpp">xsubpp</a></h2>
1271 <dl>
1272 <dt><strong><a name="item_void_xsubs_now_default_to_returning_nothing"><code>void</code> XSUBs now default to returning nothing</a></strong>
1273
1274 <dd>
1275 <p>Due to a documentation/implementation bug in previous versions of
1276 Perl, XSUBs with a return type of <code>void</code> have actually been
1277 returning one value.  Usually that value was the GV for the XSUB,
1278 but sometimes it was some already freed or reused value, which would
1279 sometimes lead to program failure.</p>
1280 </dd>
1281 <dd>
1282 <p>In Perl 5.004, if an XSUB is declared as returning <code>void</code>, it
1283 actually returns no value, i.e. an empty list (though there is a
1284 backward-compatibility exception; see below).  If your XSUB really
1285 does return an SV, you should give it a return type of <code>SV *</code>.</p>
1286 </dd>
1287 <dd>
1288 <p>For backward compatibility, <em>xsubpp</em> tries to guess whether a
1289 <code>void</code> XSUB is really <code>void</code> or if it wants to return an <code>SV *</code>.
1290 It does so by examining the text of the XSUB: if <em>xsubpp</em> finds
1291 what looks like an assignment to <code>ST(0)</code>, it assumes that the
1292 XSUB's return type is really <code>SV *</code>.</p>
1293 </dd>
1294 </li>
1295 </dl>
1296 <p>
1297 </p>
1298 <hr />
1299 <h1><a name="c_language_api_changes">C Language API Changes</a></h1>
1300 <dl>
1301 <dt><strong><a name="item_gv_fetchmethod_and_perl_call_sv"><code>gv_fetchmethod</code> and <code>perl_call_sv</code></a></strong>
1302
1303 <dd>
1304 <p>The <code>gv_fetchmethod</code> function finds a method for an object, just like
1305 in Perl 5.003.  The GV it returns may be a method cache entry.
1306 However, in Perl 5.004, method cache entries are not visible to users;
1307 therefore, they can no longer be passed directly to <code>perl_call_sv</code>.
1308 Instead, you should use the <code>GvCV</code> macro on the GV to extract its CV,
1309 and pass the CV to <code>perl_call_sv</code>.</p>
1310 </dd>
1311 <dd>
1312 <p>The most likely symptom of passing the result of <code>gv_fetchmethod</code> to
1313 <code>perl_call_sv</code> is Perl's producing an ``Undefined subroutine called''
1314 error on the <em>second</em> call to a given method (since there is no cache
1315 on the first call).</p>
1316 </dd>
1317 </li>
1318 <dt><strong><a name="item_perl_eval_pv"><code>perl_eval_pv</code></a></strong>
1319
1320 <dd>
1321 <p>A new function handy for eval'ing strings of Perl code inside C code.
1322 This function returns the value from the eval statement, which can
1323 be used instead of fetching globals from the symbol table.  See
1324 <a href="file://C|\msysgit\mingw\html/pod/perlguts.html">the perlguts manpage</a>, <a href="file://C|\msysgit\mingw\html/pod/perlembed.html">the perlembed manpage</a> and <a href="file://C|\msysgit\mingw\html/pod/perlcall.html">the perlcall manpage</a> for details and examples.</p>
1325 </dd>
1326 </li>
1327 <dt><strong><a name="item_extended_api_for_manipulating_hashes">Extended API for manipulating hashes</a></strong>
1328
1329 <dd>
1330 <p>Internal handling of hash keys has changed.  The old hashtable API is
1331 still fully supported, and will likely remain so.  The additions to the
1332 API allow passing keys as <code>SV*</code>s, so that <code>tied</code> hashes can be given
1333 real scalars as keys rather than plain strings (nontied hashes still
1334 can only use strings as keys).  New extensions must use the new hash
1335 access functions and macros if they wish to use <code>SV*</code> keys.  These
1336 additions also make it feasible to manipulate <code>HE*</code>s (hash entries),
1337 which can be more efficient.  See <a href="file://C|\msysgit\mingw\html/pod/perlguts.html">the perlguts manpage</a> for details.</p>
1338 </dd>
1339 </li>
1340 </dl>
1341 <p>
1342 </p>
1343 <hr />
1344 <h1><a name="documentation_changes">Documentation Changes</a></h1>
1345 <p>Many of the base and library pods were updated.  These
1346 new pods are included in section 1:</p>
1347 <dl>
1348 <dt><strong><a name="item_perldelta"><a href="file://C|\msysgit\mingw\html/pod/perldelta.html">the perldelta manpage</a></a></strong>
1349
1350 <dd>
1351 <p>This document.</p>
1352 </dd>
1353 </li>
1354 <dt><strong><a name="item_perlfaq"><a href="file://C|\msysgit\mingw\html/pod/perlfaq.html">the perlfaq manpage</a></a></strong>
1355
1356 <dd>
1357 <p>Frequently asked questions.</p>
1358 </dd>
1359 </li>
1360 <dt><strong><a name="item_perllocale"><a href="file://C|\msysgit\mingw\html/pod/perllocale.html">the perllocale manpage</a></a></strong>
1361
1362 <dd>
1363 <p>Locale support (internationalization and localization).</p>
1364 </dd>
1365 </li>
1366 <dt><strong><a name="item_perltoot"><a href="file://C|\msysgit\mingw\html/pod/perltoot.html">the perltoot manpage</a></a></strong>
1367
1368 <dd>
1369 <p>Tutorial on Perl OO programming.</p>
1370 </dd>
1371 </li>
1372 <dt><strong><a name="item_perlapio"><a href="file://C|\msysgit\mingw\html/pod/perlapio.html">the perlapio manpage</a></a></strong>
1373
1374 <dd>
1375 <p>Perl internal IO abstraction interface.</p>
1376 </dd>
1377 </li>
1378 <dt><strong><a name="item_perlmodlib"><a href="file://C|\msysgit\mingw\html/pod/perlmodlib.html">the perlmodlib manpage</a></a></strong>
1379
1380 <dd>
1381 <p>Perl module library and recommended practice for module creation.
1382 Extracted from <a href="file://C|\msysgit\mingw\html/pod/perlmod.html">the perlmod manpage</a> (which is much smaller as a result).</p>
1383 </dd>
1384 </li>
1385 <dt><strong><a name="item_perldebug"><a href="file://C|\msysgit\mingw\html/pod/perldebug.html">the perldebug manpage</a></a></strong>
1386
1387 <dd>
1388 <p>Although not new, this has been massively updated.</p>
1389 </dd>
1390 </li>
1391 <dt><strong><a name="item_perlsec"><a href="file://C|\msysgit\mingw\html/pod/perlsec.html">the perlsec manpage</a></a></strong>
1392
1393 <dd>
1394 <p>Although not new, this has been massively updated.</p>
1395 </dd>
1396 </li>
1397 </dl>
1398 <p>
1399 </p>
1400 <hr />
1401 <h1><a name="new_diagnostics">New Diagnostics</a></h1>
1402 <p>Several new conditions will trigger warnings that were
1403 silent before.  Some only affect certain platforms.
1404 The following new warnings and errors outline these.
1405 These messages are classified as follows (listed in
1406 increasing order of desperation):</p>
1407 <pre>
1408    (W) A warning (optional).
1409    (D) A deprecation (optional).
1410    (S) A severe warning (mandatory).
1411    (F) A fatal error (trappable).
1412    (P) An internal error you should never see (trappable).
1413    (X) A very fatal error (nontrappable).
1414    (A) An alien error message (not generated by Perl).</pre>
1415 <dl>
1416 <dt><strong><a name="item__22my_22_variable__25s_masks_earlier_declaration_i">``my'' variable %s masks earlier declaration in same scope</a></strong>
1417
1418 <dd>
1419 <p>(W) A lexical variable has been redeclared in the same scope, effectively
1420 eliminating all access to the previous instance.  This is almost always
1421 a typographical error.  Note that the earlier variable will still exist
1422 until the end of the scope or until all closure referents to it are
1423 destroyed.</p>
1424 </dd>
1425 </li>
1426 <dt><strong><a name="item__s">%s argument is not a HASH element or slice</a></strong>
1427
1428 <dd>
1429 <p>(F) The argument to <code>delete()</code> must be either a hash element, such as</p>
1430 </dd>
1431 <dd>
1432 <pre>
1433     $foo{$bar}
1434     $ref-&gt;[12]-&gt;{&quot;susie&quot;}</pre>
1435 </dd>
1436 <dd>
1437 <p>or a hash slice, such as</p>
1438 </dd>
1439 <dd>
1440 <pre>
1441     @foo{$bar, $baz, $xyzzy}
1442     @{$ref-&gt;[12]}{&quot;susie&quot;, &quot;queue&quot;}</pre>
1443 </dd>
1444 </li>
1445 <dt><strong><a name="item_allocation_too_large_3a__25lx">Allocation too large: %lx</a></strong>
1446
1447 <dd>
1448 <p>(X) You can't allocate more than 64K on an MS-DOS machine.</p>
1449 </dd>
1450 </li>
1451 <dt><strong><a name="item_allocation_too_large">Allocation too large</a></strong>
1452
1453 <dd>
1454 <p>(F) You can't allocate more than 2^31+``small amount'' bytes.</p>
1455 </dd>
1456 </li>
1457 <dt><strong><a name="item_scalar">Applying %s to %s will act on <code>scalar(%s)</code></a></strong>
1458
1459 <dd>
1460 <p>(W) The pattern match (//), substitution (s///), and transliteration (tr///)
1461 operators work on scalar values.  If you apply one of them to an array
1462 or a hash, it will convert the array or hash to a scalar value -- the
1463 length of an array, or the population info of a hash -- and then work on
1464 that scalar value.  This is probably not what you meant to do.  See
1465 <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_grep">grep in the perlfunc manpage</a> and <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_map">map in the perlfunc manpage</a> for alternatives.</p>
1466 </dd>
1467 </li>
1468 <dt><strong><a name="item_attempt_to_free_nonexistent_shared_string">Attempt to free nonexistent shared string</a></strong>
1469
1470 <dd>
1471 <p>(P) Perl maintains a reference counted internal table of strings to
1472 optimize the storage and access of hash keys and other strings.  This
1473 indicates someone tried to decrement the reference count of a string
1474 that can no longer be found in the table.</p>
1475 </dd>
1476 </li>
1477 <dt><strong><a name="item_attempt_to_use_reference_as_lvalue_in_substr">Attempt to use reference as lvalue in substr</a></strong>
1478
1479 <dd>
1480 <p>(W) You supplied a reference as the first argument to <a href="file://C|\msysgit\mingw\html/pod/perlvar.html#item_substr"><code>substr()</code></a> used
1481 as an lvalue, which is pretty strange.  Perhaps you forgot to
1482 dereference it first.  See <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#substr">substr in the perlfunc manpage</a>.</p>
1483 </dd>
1484 </li>
1485 <dt><strong><a name="item_bareword__22_25s_22_refers_to_nonexistent_package">Bareword ``%s'' refers to nonexistent package</a></strong>
1486
1487 <dd>
1488 <p>(W) You used a qualified bareword of the form <code>Foo::</code>, but
1489 the compiler saw no other uses of that namespace before that point.
1490 Perhaps you need to predeclare a package?</p>
1491 </dd>
1492 </li>
1493 <dt><strong><a name="item_can_27t_redefine_active_sort_subroutine__25s">Can't redefine active sort subroutine %s</a></strong>
1494
1495 <dd>
1496 <p>(F) Perl optimizes the internal handling of sort subroutines and keeps
1497 pointers into them.  You tried to redefine one such sort subroutine when it
1498 was currently active, which is not allowed.  If you really want to do
1499 this, you should write <code>sort { &amp;func } @x</code> instead of <code>sort func @x</code>.</p>
1500 </dd>
1501 </li>
1502 <dt><strong><a name="item_bareword">Can't use bareword (``%s'') as %s ref while ``strict refs'' in use</a></strong>
1503
1504 <dd>
1505 <p>(F) Only hard references are allowed by ``strict refs''.  Symbolic references
1506 are disallowed.  See <a href="file://C|\msysgit\mingw\html/pod/perlref.html">the perlref manpage</a>.</p>
1507 </dd>
1508 </li>
1509 <dt><strong><a name="item_cannot_resolve_method__60_25s_27_overloading__60_2">Cannot resolve method `%s' overloading `%s' in package `%s'</a></strong>
1510
1511 <dd>
1512 <p>(P) Internal error trying to resolve overloading specified by a method
1513 name (as opposed to a subroutine reference).</p>
1514 </dd>
1515 </li>
1516 <dt><strong><a name="item_constant_subroutine__25s_redefined">Constant subroutine %s redefined</a></strong>
1517
1518 <dd>
1519 <p>(S) You redefined a subroutine which had previously been eligible for
1520 inlining.  See <a href="file://C|\msysgit\mingw\html/pod/perlsub.html#constant_functions">Constant Functions in the perlsub manpage</a> for commentary and
1521 workarounds.</p>
1522 </dd>
1523 </li>
1524 <dt><strong><a name="item_constant_subroutine__25s_undefined">Constant subroutine %s undefined</a></strong>
1525
1526 <dd>
1527 <p>(S) You undefined a subroutine which had previously been eligible for
1528 inlining.  See <a href="file://C|\msysgit\mingw\html/pod/perlsub.html#constant_functions">Constant Functions in the perlsub manpage</a> for commentary and
1529 workarounds.</p>
1530 </dd>
1531 </li>
1532 <dt><strong><a name="item_copy_method_did_not_return_a_reference">Copy method did not return a reference</a></strong>
1533
1534 <dd>
1535 <p>(F) The method which overloads ``='' is buggy. See <a href="file://C|\msysgit\mingw\html/lib/overload.html#copy_constructor">Copy Constructor in the overload manpage</a>.</p>
1536 </dd>
1537 </li>
1538 <dt><strong><a name="item_died">Died</a></strong>
1539
1540 <dd>
1541 <p>(F) You passed <code>die()</code> an empty string (the equivalent of <code>die &quot;&quot;</code>) or
1542 you called it with no args and both <a href="file://C|\msysgit\mingw\html/pod/perlvar.html#item___"><code>$@</code></a> and <a href="#item___"><code>$_</code></a> were empty.</p>
1543 </dd>
1544 </li>
1545 <dt><strong><a name="item_exiting_pseudo_2dblock_via__25s">Exiting pseudo-block via %s</a></strong>
1546
1547 <dd>
1548 <p>(W) You are exiting a rather special block construct (like a sort block or
1549 subroutine) by unconventional means, such as a goto, or a loop control
1550 statement.  See <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_sort">sort in the perlfunc manpage</a>.</p>
1551 </dd>
1552 </li>
1553 <dt><strong><a name="item_identifier_too_long">Identifier too long</a></strong>
1554
1555 <dd>
1556 <p>(F) Perl limits identifiers (names for variables, functions, etc.) to
1557 252 characters for simple names, somewhat more for compound names (like
1558 <code>$A::B</code>).  You've exceeded Perl's limits.  Future versions of Perl are
1559 likely to eliminate these arbitrary limitations.</p>
1560 </dd>
1561 </li>
1562 <dt><strong><a name="item_s">Illegal character %s (carriage return)</a></strong>
1563
1564 <dd>
1565 <p>(F) A carriage return character was found in the input.  This is an
1566 error, and not a warning, because carriage return characters can break
1567 multi-line strings, including here documents (e.g., <code>print &lt;&lt;EOF;</code>).</p>
1568 </dd>
1569 </li>
1570 <dt><strong><a name="item_illegal_switch_in_perl5opt_3a__25s">Illegal switch in PERL5OPT: %s</a></strong>
1571
1572 <dd>
1573 <p>(X) The PERL5OPT environment variable may only be used to set the
1574 following switches: <strong>-[DIMUdmw]</strong>.</p>
1575 </dd>
1576 </li>
1577 <dt><strong><a name="item_integer_overflow_in_hex_number">Integer overflow in hex number</a></strong>
1578
1579 <dd>
1580 <p>(S) The literal hex number you have specified is too big for your
1581 architecture. On a 32-bit architecture the largest hex literal is
1582 0xFFFFFFFF.</p>
1583 </dd>
1584 </li>
1585 <dt><strong><a name="item_integer_overflow_in_octal_number">Integer overflow in octal number</a></strong>
1586
1587 <dd>
1588 <p>(S) The literal octal number you have specified is too big for your
1589 architecture. On a 32-bit architecture the largest octal literal is
1590 037777777777.</p>
1591 </dd>
1592 </li>
1593 <dt><strong><a name="item_internal_error_3a_glob_failed">internal error: glob failed</a></strong>
1594
1595 <dd>
1596 <p>(P) Something went wrong with the external <code>program(s)</code> used for <a href="#item_glob"><code>glob</code></a>
1597 and <code>&lt;*.c&gt;</code>.  This may mean that your csh (C shell) is
1598 broken.  If so, you should change all of the csh-related variables in
1599 config.sh:  If you have tcsh, make the variables refer to it as if it
1600 were csh (e.g. <code>full_csh='/usr/bin/tcsh'</code>); otherwise, make them all
1601 empty (except that <code>d_csh</code> should be <code>'undef'</code>) so that Perl will
1602 think csh is missing.  In either case, after editing config.sh, run
1603 <code>./Configure -S</code> and rebuild Perl.</p>
1604 </dd>
1605 </li>
1606 <dt><strong><a name="item_invalid_conversion_in__25s_3a__22_25s_22">Invalid conversion in %s: ``%s''</a></strong>
1607
1608 <dd>
1609 <p>(W) Perl does not understand the given format conversion.
1610 See <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#sprintf">sprintf in the perlfunc manpage</a>.</p>
1611 </dd>
1612 </li>
1613 <dt><strong><a name="item_invalid_type_in_pack_3a__27_25s_27">Invalid type in pack: '%s'</a></strong>
1614
1615 <dd>
1616 <p>(F) The given character is not a valid pack type.  See <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#pack">pack in the perlfunc manpage</a>.</p>
1617 </dd>
1618 </li>
1619 <dt><strong><a name="item_invalid_type_in_unpack_3a__27_25s_27">Invalid type in unpack: '%s'</a></strong>
1620
1621 <dd>
1622 <p>(F) The given character is not a valid unpack type.  See <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#unpack">unpack in the perlfunc manpage</a>.</p>
1623 </dd>
1624 </li>
1625 <dt><strong><a name="item_name__22_25s_3a_3a_25s_22_used_only_once_3a_possib">Name ``%s::%s'' used only once: possible typo</a></strong>
1626
1627 <dd>
1628 <p>(W) Typographical errors often show up as unique variable names.
1629 If you had a good reason for having a unique name, then just mention
1630 it again somehow to suppress the message (the <code>use vars</code> pragma is
1631 provided for just this purpose).</p>
1632 </dd>
1633 </li>
1634 <dt><strong><a name="item_null_picture_in_formline">Null picture in formline</a></strong>
1635
1636 <dd>
1637 <p>(F) The first argument to formline must be a valid format picture
1638 specification.  It was found to be empty, which probably means you
1639 supplied it an uninitialized value.  See <a href="file://C|\msysgit\mingw\html/pod/perlform.html">the perlform manpage</a>.</p>
1640 </dd>
1641 </li>
1642 <dt><strong><a name="item_offset_outside_string">Offset outside string</a></strong>
1643
1644 <dd>
1645 <p>(F) You tried to do a read/write/send/recv operation with an offset
1646 pointing outside the buffer.  This is difficult to imagine.
1647 The sole exception to this is that <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_sysread"><code>sysread()</code></a>ing past the buffer
1648 will extend the buffer and zero pad the new area.</p>
1649 </dd>
1650 </li>
1651 <dt><strong><a name="item_out_of_memory_21">Out of memory!</a></strong>
1652
1653 <dd>
1654 <p>(X|F) The <code>malloc()</code> function returned 0, indicating there was insufficient
1655 remaining memory (or virtual memory) to satisfy the request.</p>
1656 </dd>
1657 <dd>
1658 <p>The request was judged to be small, so the possibility to trap it
1659 depends on the way Perl was compiled.  By default it is not trappable.
1660 However, if compiled for this, Perl may use the contents of <a href="#item___m"><code>$^M</code></a> as
1661 an emergency pool after die()ing with this message.  In this case the
1662 error is trappable <em>once</em>.</p>
1663 </dd>
1664 </li>
1665 <dt><strong><a name="item_out_of_memory_during_request_for__25s">Out of memory during request for %s</a></strong>
1666
1667 <dd>
1668 <p>(F) The <code>malloc()</code> function returned 0, indicating there was insufficient
1669 remaining memory (or virtual memory) to satisfy the request. However,
1670 the request was judged large enough (compile-time default is 64K), so
1671 a possibility to shut down by trapping this error is granted.</p>
1672 </dd>
1673 </li>
1674 <dt><strong><a name="item_panic_3a_frexp">panic: frexp</a></strong>
1675
1676 <dd>
1677 <p>(P) The library function <code>frexp()</code> failed, making <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_printf"><code>printf(``%f'')</code></a> impossible.</p>
1678 </dd>
1679 </li>
1680 <dt><strong>Possible attempt to put comments in <code>qw()</code> list</strong>
1681
1682 <dd>
1683 <p>(W) <a href="#item_qw"><code>qw()</code></a> lists contain items separated by whitespace; as with literal
1684 strings, comment characters are not ignored, but are instead treated
1685 as literal data.  (You may have used different delimiters than the
1686 parentheses shown here; braces are also frequently used.)</p>
1687 </dd>
1688 <dd>
1689 <p>You probably wrote something like this:</p>
1690 </dd>
1691 <dd>
1692 <pre>
1693     @list = qw(
1694         a # a comment
1695         b # another comment
1696     );</pre>
1697 </dd>
1698 <dd>
1699 <p>when you should have written this:</p>
1700 </dd>
1701 <dd>
1702 <pre>
1703     @list = qw(
1704         a
1705         b
1706     );</pre>
1707 </dd>
1708 <dd>
1709 <p>If you really want comments, build your list the
1710 old-fashioned way, with quotes and commas:</p>
1711 </dd>
1712 <dd>
1713 <pre>
1714     @list = (
1715         'a',    # a comment
1716         'b',    # another comment
1717     );</pre>
1718 </dd>
1719 </li>
1720 <dt><strong><a name="item_possible_attempt_to_separate_words_with_commas">Possible attempt to separate words with commas</a></strong>
1721
1722 <dd>
1723 <p>(W) <a href="#item_qw"><code>qw()</code></a> lists contain items separated by whitespace; therefore commas
1724 aren't needed to separate the items. (You may have used different
1725 delimiters than the parentheses shown here; braces are also frequently
1726 used.)</p>
1727 </dd>
1728 <dd>
1729 <p>You probably wrote something like this:</p>
1730 </dd>
1731 <dd>
1732 <pre>
1733     qw! a, b, c !;</pre>
1734 </dd>
1735 <dd>
1736 <p>which puts literal commas into some of the list items.  Write it without
1737 commas if you don't want them to appear in your data:</p>
1738 </dd>
1739 <dd>
1740 <pre>
1741     qw! a b c !;</pre>
1742 </dd>
1743 </li>
1744 <dt><strong><a name="item_scalar_value__40_25s_7b_25s_7d_better_written_as__">Scalar value @%s{%s} better written as $%s{%s}</a></strong>
1745
1746 <dd>
1747 <p>(W) You've used a hash slice (indicated by @) to select a single element of
1748 a hash.  Generally it's better to ask for a scalar value (indicated by $).
1749 The difference is that <code>$foo{&amp;bar}</code> always behaves like a scalar, both when
1750 assigning to it and when evaluating its argument, while <code>@foo{&amp;bar}</code> behaves
1751 like a list when you assign to it, and provides a list context to its
1752 subscript, which can do weird things if you're expecting only one subscript.</p>
1753 </dd>
1754 </li>
1755 <dt><strong><a name="item_stub_found_while_resolving_method__60_25s_27_overl">Stub found while resolving method `%s' overloading `%s' in %s</a></strong>
1756
1757 <dd>
1758 <p>(P) Overloading resolution over @ISA tree may be broken by importing stubs.
1759 Stubs should never be implicitly created, but explicit calls to <a href="#item_can"><code>can</code></a>
1760 may break this.</p>
1761 </dd>
1762 </li>
1763 <dt><strong><a name="item_too_late_for__22_2dt_22_option">Too late for ``<strong>-T</strong>'' option</a></strong>
1764
1765 <dd>
1766 <p>(X) The #! line (or local equivalent) in a Perl script contains the
1767 <strong>-T</strong> option, but Perl was not invoked with <strong>-T</strong> in its argument
1768 list.  This is an error because, by the time Perl discovers a <strong>-T</strong> in
1769 a script, it's too late to properly taint everything from the
1770 environment.  So Perl gives up.</p>
1771 </dd>
1772 </li>
1773 <dt><strong><a name="item_untie_attempted_while__25d_inner_references_still_">untie attempted while %d inner references still exist</a></strong>
1774
1775 <dd>
1776 <p>(W) A copy of the object returned from <code>tie</code> (or <code>tied</code>) was still
1777 valid when <code>untie</code> was called.</p>
1778 </dd>
1779 </li>
1780 <dt><strong><a name="item_unrecognized_character__25s">Unrecognized character %s</a></strong>
1781
1782 <dd>
1783 <p>(F) The Perl parser has no idea what to do with the specified character
1784 in your Perl script (or eval).  Perhaps you tried to run a compressed
1785 script, a binary program, or a directory as a Perl program.</p>
1786 </dd>
1787 </li>
1788 <dt><strong><a name="item_unsupported_function_fork">Unsupported function fork</a></strong>
1789
1790 <dd>
1791 <p>(F) Your version of executable does not support forking.</p>
1792 </dd>
1793 <dd>
1794 <p>Note that under some systems, like OS/2, there may be different flavors of
1795 Perl executables, some of which may support fork, some not. Try changing
1796 the name you call Perl by to <code>perl_</code>, <code>perl__</code>, and so on.</p>
1797 </dd>
1798 </li>
1799 <dt><strong><a name="item_use_of__22_24_24_3cdigit_3e_22_to_mean__22_24_7b_2">Use of ``$$&lt;digit&gt;'' to mean ``${$}&lt;digit&gt;'' is deprecated</a></strong>
1800
1801 <dd>
1802 <p>(D) Perl versions before 5.004 misinterpreted any type marker followed
1803 by ``$'' and a digit.  For example, ``$$0'' was incorrectly taken to mean
1804 ``${$}0'' instead of ``${$0}''.  This bug is (mostly) fixed in Perl 5.004.</p>
1805 </dd>
1806 <dd>
1807 <p>However, the developers of Perl 5.004 could not fix this bug completely,
1808 because at least two widely-used modules depend on the old meaning of
1809 ``$$0'' in a string.  So Perl 5.004 still interprets ``$$&lt;digit&gt;'' in the
1810 old (broken) way inside strings; but it generates this message as a
1811 warning.  And in Perl 5.005, this special treatment will cease.</p>
1812 </dd>
1813 </li>
1814 <dt><strong><a name="item_defined">Value of %s can be ``0''; test with <code>defined()</code></a></strong>
1815
1816 <dd>
1817 <p>(W) In a conditional expression, you used &lt;HANDLE&gt;, &lt;*&gt; (glob), <code>each()</code>,
1818 or <code>readdir()</code> as a boolean value.  Each of these constructs can return a
1819 value of ``0''; that would make the conditional expression false, which is
1820 probably not what you intended.  When using these constructs in conditional
1821 expressions, test their values with the <a href="#item_defined"><code>defined</code></a> operator.</p>
1822 </dd>
1823 </li>
1824 <dt><strong><a name="item_variable__22_25s_22_may_be_unavailable">Variable ``%s'' may be unavailable</a></strong>
1825
1826 <dd>
1827 <p>(W) An inner (nested) <em>anonymous</em> subroutine is inside a <em>named</em>
1828 subroutine, and outside that is another subroutine; and the anonymous
1829 (innermost) subroutine is referencing a lexical variable defined in
1830 the outermost subroutine.  For example:</p>
1831 </dd>
1832 <dd>
1833 <pre>
1834    sub outermost { my $a; sub middle { sub { $a } } }</pre>
1835 </dd>
1836 <dd>
1837 <p>If the anonymous subroutine is called or referenced (directly or
1838 indirectly) from the outermost subroutine, it will share the variable
1839 as you would expect.  But if the anonymous subroutine is called or
1840 referenced when the outermost subroutine is not active, it will see
1841 the value of the shared variable as it was before and during the
1842 *first* call to the outermost subroutine, which is probably not what
1843 you want.</p>
1844 </dd>
1845 <dd>
1846 <p>In these circumstances, it is usually best to make the middle
1847 subroutine anonymous, using the <code>sub {}</code> syntax.  Perl has specific
1848 support for shared variables in nested anonymous subroutines; a named
1849 subroutine in between interferes with this feature.</p>
1850 </dd>
1851 </li>
1852 <dt><strong><a name="item_variable__22_25s_22_will_not_stay_shared">Variable ``%s'' will not stay shared</a></strong>
1853
1854 <dd>
1855 <p>(W) An inner (nested) <em>named</em> subroutine is referencing a lexical
1856 variable defined in an outer subroutine.</p>
1857 </dd>
1858 <dd>
1859 <p>When the inner subroutine is called, it will probably see the value of
1860 the outer subroutine's variable as it was before and during the
1861 *first* call to the outer subroutine; in this case, after the first
1862 call to the outer subroutine is complete, the inner and outer
1863 subroutines will no longer share a common value for the variable.  In
1864 other words, the variable will no longer be shared.</p>
1865 </dd>
1866 <dd>
1867 <p>Furthermore, if the outer subroutine is anonymous and references a
1868 lexical variable outside itself, then the outer and inner subroutines
1869 will <em>never</em> share the given variable.</p>
1870 </dd>
1871 <dd>
1872 <p>This problem can usually be solved by making the inner subroutine
1873 anonymous, using the <code>sub {}</code> syntax.  When inner anonymous subs that
1874 reference variables in outer subroutines are called or referenced,
1875 they are automatically rebound to the current values of such
1876 variables.</p>
1877 </dd>
1878 </li>
1879 <dt><strong><a name="item_warning_3a_something_27s_wrong">Warning: something's wrong</a></strong>
1880
1881 <dd>
1882 <p>(W) You passed <code>warn()</code> an empty string (the equivalent of <code>warn &quot;&quot;</code>) or
1883 you called it with no args and <a href="#item___"><code>$_</code></a> was empty.</p>
1884 </dd>
1885 </li>
1886 <dt><strong><a name="item_ill_2dformed_logical_name__7c_25s_7c_in_prime_env_">Ill-formed logical name |%s| in prime_env_iter</a></strong>
1887
1888 <dd>
1889 <p>(W) A warning peculiar to VMS.  A logical name was encountered when preparing
1890 to iterate over %ENV which violates the syntactic rules governing logical
1891 names.  Since it cannot be translated normally, it is skipped, and will not
1892 appear in %ENV.  This may be a benign occurrence, as some software packages
1893 might directly modify logical name tables and introduce nonstandard names,
1894 or it may indicate that a logical name table has been corrupted.</p>
1895 </dd>
1896 </li>
1897 <dt><strong><a name="item_got_an_error_from_dosallocmem">Got an error from DosAllocMem</a></strong>
1898
1899 <dd>
1900 <p>(P) An error peculiar to OS/2.  Most probably you're using an obsolete
1901 version of Perl, and this should not happen anyway.</p>
1902 </dd>
1903 </li>
1904 <dt><strong><a name="item_malformed_perllib_prefix">Malformed PERLLIB_PREFIX</a></strong>
1905
1906 <dd>
1907 <p>(F) An error peculiar to OS/2.  PERLLIB_PREFIX should be of the form</p>
1908 </dd>
1909 <dd>
1910 <pre>
1911     prefix1;prefix2</pre>
1912 </dd>
1913 <dd>
1914 <p>or</p>
1915 </dd>
1916 <dd>
1917 <pre>
1918     prefix1 prefix2</pre>
1919 </dd>
1920 <dd>
1921 <p>with nonempty prefix1 and prefix2.  If <code>prefix1</code> is indeed a prefix
1922 of a builtin library search path, prefix2 is substituted.  The error
1923 may appear if components are not found, or are too long.  See
1924 ``PERLLIB_PREFIX'' in <em>README.os2</em>.</p>
1925 </dd>
1926 </li>
1927 <dt><strong><a name="item_perl_sh_dir_too_long">PERL_SH_DIR too long</a></strong>
1928
1929 <dd>
1930 <p>(F) An error peculiar to OS/2. PERL_SH_DIR is the directory to find the
1931 <code>sh</code>-shell in.  See ``PERL_SH_DIR'' in <em>README.os2</em>.</p>
1932 </dd>
1933 </li>
1934 <dt><strong><a name="item_process_terminated_by_sig_25s">Process terminated by SIG%s</a></strong>
1935
1936 <dd>
1937 <p>(W) This is a standard message issued by OS/2 applications, while *nix
1938 applications die in silence.  It is considered a feature of the OS/2
1939 port.  One can easily disable this by appropriate sighandlers, see
1940 <a href="file://C|\msysgit\mingw\html/pod/perlipc.html#signals">Signals in the perlipc manpage</a>.  See also ``Process terminated by SIGTERM/SIGINT''
1941 in <em>README.os2</em>.</p>
1942 </dd>
1943 </li>
1944 </dl>
1945 <p>
1946 </p>
1947 <hr />
1948 <h1><a name="bugs">BUGS</a></h1>
1949 <p>If you find what you think is a bug, you might check the headers of
1950 recently posted articles in the comp.lang.perl.misc newsgroup.
1951 There may also be information at <a href="http://www.perl.com/perl/">http://www.perl.com/perl/</a> , the Perl
1952 Home Page.</p>
1953 <p>If you believe you have an unreported bug, please run the <strong>perlbug</strong>
1954 program included with your release.  Make sure you trim your bug down
1955 to a tiny but sufficient test case.  Your bug report, along with the
1956 output of <code>perl -V</code>, will be sent off to &lt;<em><a href="mailto:perlbug@perl.com">perlbug@perl.com</a></em>&gt; to be
1957 analysed by the Perl porting team.</p>
1958 <p>
1959 </p>
1960 <hr />
1961 <h1><a name="see_also">SEE ALSO</a></h1>
1962 <p>The <em>Changes</em> file for exhaustive details on what changed.</p>
1963 <p>The <em>INSTALL</em> file for how to build Perl.  This file has been
1964 significantly updated for 5.004, so even veteran users should
1965 look through it.</p>
1966 <p>The <em>README</em> file for general stuff.</p>
1967 <p>The <em>Copying</em> file for copyright information.</p>
1968 <p>
1969 </p>
1970 <hr />
1971 <h1><a name="history">HISTORY</a></h1>
1972 <p>Constructed by Tom Christiansen, grabbing material with permission
1973 from innumerable contributors, with kibitzing by more than a few Perl
1974 porters.</p>
1975 <p>Last update: Wed May 14 11:14:09 EDT 1997</p>
1976 <table border="0" width="100%" cellspacing="0" cellpadding="3">
1977 <tr><td class="block" style="background-color: #cccccc" valign="middle">
1978 <big><strong><span class="block">&nbsp;perl5004delta - what's new for perl5.004</span></strong></big>
1979 </td></tr>
1980 </table>
1981
1982 </body>
1983
1984 </html>