perl-policy.sgml

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   6
   7 <debiandoc>
   8   <book>
   9     <titlepag>
  10       <title>Debian Perl Policy</title>
  11       <author>
  12         <name>Rapha&euml;l Hertzog</name>
  13       </author>
  14       <author>
  15         <name>Brendan O'Dea</name>
  16       </author>
  17       <author>
  18         <name>The Debian Policy mailing list</name>
  19         <email>debian-policy@lists.debian.org</email>
  20       </author>
  21       <version>version &version;, &date;</version>
  22
  23       <abstract>
  24         This document describes the packaging of Perl within the Debian
  25         distribution and the policy requirements for packaged
  26         Perl programs and modules.
  27       </abstract>
  28
  29       <copyright>
  30         <copyrightsummary>
  31           Copyright &copy; 1999, 2001 Software in the Public Interest
  32         </copyrightsummary>
  33         <p>
  34           This manual is free software; you can redistribute it and/or
  35           modify it under the terms of the GNU General Public License
  36           as published by the Free Software Foundation; either version
  37           2 of the License, or (at your option) any later version.
  38         </p>
  39         <p>
  40           This is distributed in the hope that it will be useful, but
  41           WITHOUT ANY WARRANTY; without even the implied warranty of
  42           MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  43           the GNU General Public License for more details.
  44         </p>
  45         <p>
  46           A copy of the GNU General Public License is available as
  47           <tt>/usr/share/common-licenses/GPL</tt> in the Debian
  48           distribution or on the World Wide Web at
  49           <url id="http://www.gnu.org/copyleft/gpl.html"
  50           name="The GNU Public Licence">.
  51         </p>
  52         <p>
  53           You can also obtain it by writing to the
  54           Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
  55           Boston, MA 02110-1301, USA.
  56         </p>
  57       </copyright>
  58     </titlepag>
  59
  60     <toc detail="sect">
  61
  62     <chapt>
  63       <heading>About this document</heading>
  64       <p>
  65         This document is distributed as the <tt>perl-policy</tt> files
  66         in the Debian package
  67         <package><url name="debian-policy" id="http://packages.debian.org/debian-policy"></package>.
  68         It is also available from the Debian web mirrors at
  69         <tt><url name="/doc/packaging-manuals/perl-policy/"
  70                 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
  71       </p>
  72     </chapt>
  73
  74     <chapt id="perl">
  75       <heading>Perl Packaging</heading>
  76       <sect id="versions">
  77         <heading>Versions</heading>
  78         <p>
  79           At any given time, the package <package>perl</package> should
  80           represent the current stable upstream version of Perl revision
  81           5 (see <ref id="perl6">).
  82         </p>
  83         <p>
  84           Only one package may contain the <file>/usr/bin/perl</file>
  85           binary and that package must either be <package>perl</package>
  86           or a dependency of that package (see <ref id="base">).
  87         </p>
  88         <p>
  89           Where possible, Perl should be compiled to provide binary
  90           compatibility to at least the last released package version to
  91           allow a grace period over which binary module packages may be
  92           re-built against the new package (see <ref id="binary_modules">).
  93         </p>
  94         <p>
  95           The <package>perl-base</package> package must provide
  96           <package>perlapi-<var>abiname</var></package> for all released
  97           package versions it is compatible with. The choice of
  98           <var>abiname</var> is arbitrary, but if it differs from
  99           <tt>$Config{version}</tt>, it must be specified in
 100           <tt>$Config{debian_abi}</tt>.
 101         </p>
 102       </sect>
 103
 104       <sect id="base">
 105         <heading>Base Package</heading>
 106         <p>
 107           In order to provide a minimal installation of Perl for use by
 108           applications without requiring the whole of Perl to be
 109           installed, the <package>perl-base</package> package contains
 110           the binary and a basic set of modules.
 111         </p>
 112         <p>
 113           As Perl has been part of the essential set for some time and is
 114           used without dependencies by such things as package maintainer
 115           scripts, <package>perl-base</package> must be
 116           priority <em>required</em> and marked as <em>essential</em>.
 117         </p>
 118         <p>
 119           Note that the <package>perl-base</package> package is intended
 120           only to provide for exceptional circumstances and the contents
 121           may change.  In general, only packages which form part of the
 122           base system should use only the facilities
 123           of <package>perl-base</package> rather than declaring a
 124           dependency on <package>perl</package>.
 125         </p>
 126       </sect>
 127
 128       <sect id="paths">
 129         <heading>Module Path</heading>
 130         <p>
 131           Perl searches three different locations for modules, referred
 132           to in this document as <var>core</var> in which modules
 133           distributed with Perl are installed, <var>vendor</var> for
 134           packaged modules and <var>site</var> for modules installed by
 135           the local administrator.
 136         </p>
 137         <p>
 138           The module search path (<tt>@INC</tt>) in the Debian packages
 139           has been ordered to include these locations in the following
 140           order:
 141           <taglist>
 142             <tag><var>site</var> (current)</tag>
 143             <item>
 144               <p>
 145                 Modules installed by the local administrator for the
 146                 current version of Perl (see <ref id="site">).
 147                 <example>
 148 /usr/local/lib/perl/<var>version</var>
 149 /usr/local/share/perl/<var>version</var>
 150                 </example>
 151                 Where <var>version</var> indicates the current Perl
 152                 version (<tt>$Config{version}</tt><footnote>see the
 153                 <tt>Config</tt> module</footnote>).
 154               </p>
 155             </item>
 156             <tag><var>vendor</var></tag>
 157             <item>
 158               <p>
 159                 Packaged modules (see <ref id="module_packages">).
 160                 <example>
 161 /usr/lib/perl5
 162 /usr/share/perl5
 163                 </example>
 164               </p>
 165             </item>
 166             <tag><var>core</var></tag>
 167             <item>
 168               <p>
 169                 Modules included in the core Perl distribution.
 170                 <example>
 171 /usr/lib/perl/<var>version</var>
 172 /usr/share/perl/<var>version</var>
 173                 </example>
 174               </p>
 175             </item>
 176             <tag><var>site</var> (old)</tag>
 177             <item>
 178               <p>
 179                 <var>site</var> directories (as above) for modules
 180                 installed with previously released
 181                 <package>perl</package> packages for which the current
 182                 package is binary compatible are included if present.
 183               </p>
 184             </item>
 185           </taglist>
 186           In each of the directory pairs above, the <file>lib</file>
 187           component is for binary (XS) modules, and <file>share</file>
 188           for architecture-independent (pure-perl) modules.
 189         </p>
 190       </sect>
 191
 192       <sect id="docs">
 193         <heading>Documentation</heading>
 194         <p>
 195           The POD files and manual pages which do not refer to programs
 196           may be split out into a separate <package>perl-doc</package>
 197           package.
 198         </p>
 199         <p>
 200           Manual pages distributed with Perl packages must be installed
 201           into the standard directories:
 202           <taglist>
 203             <tag>Programs</tag>
 204             <item>
 205               <p>
 206                 Manual pages for programs and scripts are installed into
 207                 <file>/usr/share/man/man1</file> with the extension
 208                 <tt>.1</tt>.
 209               </p>
 210             </item>
 211             <tag>Modules</tag>
 212             <item>
 213               <p>
 214                 Manual pages for modules are installed into
 215                 <file>/usr/share/man/man3</file> with the extension
 216                 <tt>.3perl</tt>.
 217               </p>
 218             </item>
 219           </taglist>
 220         </p>
 221       </sect>
 222     </chapt>
 223
 224     <chapt id="site">
 225       <heading>Locally Installed Modules</heading>
 226       <sect id="site_dirs">
 227         <heading>Site Directories</heading>
 228         <p>
 229           The Perl packages must provide a mechanism for the local
 230           administrator to install modules under <file>/usr/local</file>
 231           but must not create or remove those directories.
 232         </p>
 233         <p>
 234           Modules should be installed to the directories described above
 235           in <ref id="paths"> as <var>site</var> (current), programs to
 236           <file>/usr/local/bin</file> and manual pages under
 237           <file>/usr/local/man</file>.
 238         </p>
 239       </sect>
 240
 241       <sect id="site_install">
 242         <heading>Site Installation</heading>
 243         <p>
 244           The following commands should be sufficient in the majority of
 245           cases for the local administrator to install modules and must
 246           create directories as required:
 247           <example>
 248 perl Makefile.PL
 249 make install
 250           </example>
 251         </p>
 252       </sect>
 253     </chapt>
 254
 255     <chapt id="module_packages">
 256       <heading>Packaged Modules</heading>
 257       <sect id="vendor_dirs">
 258         <heading>Vendor Directories</heading>
 259         <p>
 260           The installation directory for Debian modules must be
 261           different from that for <var>core</var> and <var>site</var>
 262           modules.
 263         </p>
 264         <p>
 265           The current Perl packaging uses the <var>vendor</var>
 266           directories for this purpose, which are at present as
 267           described in <ref id="paths"> as <var>vendor</var>.
 268         </p>
 269         <p>
 270           No version subdirectory exists on these directories as the
 271           dependencies for packaged modules (see <ref id="module_deps">)
 272           should ensure that all work with the current
 273           <package>perl</package> package.
 274         </p>
 275         <p>
 276           The Perl distribution includes many modules available
 277           separately from CPAN<footnote><url
 278           id="http://www.perl.com/CPAN"></footnote>, which may have a
 279           newer version.  The intent of the <tt>@INC</tt> ordering
 280           (described in <ref id="paths">) is to allow such modules to be
 281           packaged to <var>vendor</var> which take precedence over the
 282           version in <var>core</var>.  A packaged module which shadows a
 283           <var>core</var> module in this way must be a newer version.
 284         </p>
 285         <p>
 286           Module packages must install manual pages into the standard
 287           directories (see <ref id="docs">) using the extensions
 288           <tt>.1p</tt> and <tt>.3pm</tt> to ensure that no conflict
 289           arises where a packaged module duplicates a <var>core</var>
 290           module.
 291         </p>
 292         <p>
 293           <file>.packlist</file> files should not be installed.
 294         </p>
 295       </sect>
 296
 297       <sect id="package_names">
 298         <heading>Module Package Names</heading>
 299         <p>
 300           Perl module packages should be named for the primary module
 301           provided.  The naming convention is to lowercase the Perl module
 302           name, prepend, <tt>lib</tt>, change all occurrences
 303           of <tt>::</tt> to <tt>-</tt>, and append <tt>-perl</tt>.  For
 304           example:
 305           <example>
 306 Foo::Bar        libfoo-bar-perl
 307 Foo::Bar::Baz   libfoo-bar-baz-perl
 308 Foo::BarBaz     libfoo-barbaz-perl
 309           </example>
 310           Packages which include multiple modules may additionally include
 311           provides for the additional modules using the same convention.
 312         </p>
 313       </sect>
 314
 315       <sect id="vendor_install">
 316         <heading>Vendor Installation</heading>
 317         <p>
 318           A module should use the following lines in the
 319           <file>debian/rules</file> <tt>build</tt>
 320           target<footnote>The environment variable <tt>PERL_MM_OPT</tt>
 321           may be used to pass the <tt>INSTALLDIRS=vendor</tt> option in
 322           cases where <file>Makefile.PL</file> is not invoked directly
 323           from <file>debian/rules</file></footnote>:
 324           <example>
 325 perl Makefile.PL INSTALLDIRS=vendor
 326 $(MAKE) OPTIMIZE="-O2 -g -Wall"
 327           </example>
 328           and this one to install the results into the temporary tree:
 329           <example>
 330 $(MAKE) install DESTDIR=$(CURDIR)/debian/&lt;tmp&gt;
 331           </example><footnote>
 332             <p>Replace &lt;tmp&gt; with the appropriate directory
 333             (nominally just tmp)</p>
 334           </footnote>
 335         </p>
 336       </sect>
 337
 338       <sect id="module_deps">
 339         <heading>Module Dependencies</heading>
 340         <sect1 id="indep_modules">
 341           <heading>Architecture-Independent Modules</heading>
 342           <p>
 343             Architecture-independent modules which require
 344             <var>core</var> modules from the <package>perl</package>
 345             package must specify a dependency on that package.
 346           </p>
 347           <p>
 348             Modules which contain explicit <tt>require
 349             <var>version</var></tt> or <tt>use <var>version</var></tt>
 350             statements must specify a dependency on
 351             <package>perl</package> or <package>perl-base</package> with
 352             the minimum required version, or more simply the current
 353             version.
 354           </p>
 355         </sect1>
 356
 357         <sect1 id="binary_modules">
 358           <heading>Binary Modules</heading>
 359           <p>
 360             Binary modules must specify a dependency on either
 361             <package>perl</package> or <package>perl-base</package> with
 362             a minimum version of the <package>perl</package> package
 363             used to build the module, and must additionally depend on
 364             the expansion of
 365             <package>perlapi-$Config{debian_abi}</package> using
 366             the <tt>Config</tt> module. If <tt>$Config{debian_abi}</tt>
 367             is empty or not set, <tt>$Config{version}</tt> must be used.
 368           </p>
 369         </sect1>
 370
 371         <sect1 id="dh_perl">
 372           <heading>Automating Perl Dependencies</heading>
 373           <p>
 374             Rather than hard-coding the dependencies into the control
 375             file, using a substitution such as <tt>${perl:Depends}</tt>
 376             is suggested.  This allows the dependencies to be determined
 377             at build time and written to the <file>substvars</file> file
 378             in the form
 379             <tt>perl:Depends=<var>deps</var></tt>.<footnote>
 380               <p>Please note that dependencies caused by versioned
 381               uses and on separately packaged modules are not included
 382               in this variable and must be explicitly included.</p>
 383             </footnote>
 384           </p>
 385           <p>
 386             Packages built with <prgn>debhelper</prgn> may use
 387
 388             <manref name="dh_perl" section="1"> to generate this
 389             substitution automatically.  This additionally requires a
 390             versioned <tt>Build-Depends</tt> (or
 391             <tt>Build-Depends-Indep</tt>) on <tt>debhelper (>=
 392             3.0.18)</tt>.
 393           </p>
 394         </sect1>
 395       </sect>
 396     </chapt>
 397
 398     <chapt id="programs">
 399       <heading>Perl Programs</heading>
 400       <sect id="hash_bang">
 401         <heading>Script Magic</heading>
 402         <p>
 403           All packaged perl programs must start with
 404           <tt>#!/usr/bin/perl</tt> and may append such flags as are
 405           required.
 406         </p>
 407       </sect>
 408
 409       <sect id="program_deps">
 410         <heading>Program Dependencies</heading>
 411         <p>
 412           Programs which require <var>core</var> modules from the
 413           <package>perl</package> package must specify a dependency on
 414           that package.
 415         </p>
 416         <p>
 417           Programs which contain explicit <tt>require
 418           <var>version</var></tt> or <tt>use <var>version</var></tt>
 419           statements must specify a dependency on
 420           <package>perl</package> or <package>perl-base</package> with
 421           the minimum required version, or more simply the current
 422           version.
 423         </p>
 424         <p>
 425           As with modules, packages using <prgn>debhelper</prgn> may use
 426           <manref name="dh_perl" section="1"> to automatically generate
 427           dependences (see <ref id="dh_perl">).
 428         </p>
 429       </sect>
 430     </chapt>
 431
 432     <chapt id="embed">
 433       <heading>Programs Embedding Perl</heading>
 434       <sect id="build_embedded">
 435         <heading>Building Embedded Programs</heading>
 436         <p>
 437           Programs which embed a perl interpreter must declare a
 438           <tt>Build-Depends</tt> on <package>libperl-dev</package>.
 439         </p>
 440         <p>
 441           The default linker options produced by
 442           <example>
 443 perl -MExtUtils::Embed -e ldopts
 444           </example>
 445           will link against the dynamic <tt>libperl</tt>.  If programs
 446           wish to link to the static library, then <tt>-lperl</tt>
 447           should be changed to <file>/usr/lib/libperl.a</file> in those
 448           options.
 449         </p>
 450       </sect>
 451
 452       <sect id="embedded_deps">
 453         <heading>Embedded Perl Dependencies</heading>
 454         <p>
 455           Dependencies for programs linking against the shared Perl
 456           library will be automatically created by
 457           <prgn>dpkg-shlibdeps</prgn>.  Note however that the shared
 458           perl library package only suggests
 459           <package>perl-base</package> and packages requiring any
 460           <var>core</var> modules from the <package>perl</package>
 461           package must depend upon it explicitly.
 462         </p>
 463       </sect>
 464     </chapt>
 465
 466     <appendix id="perl6">
 467       <heading>Perl 6</heading>
 468       <p>
 469         The current stable upstream version at the time of this writing
 470         is 5.6.0.  There is currently work in progress on the next major
 471         revision, although the specifications have yet to be finalised.
 472       </p>
 473       <p>
 474         It is anticipated that when Perl 6 is released it will initially
 475         be packaged as <package>perl6</package>, install the binary as
 476         <file>/usr/bin/perl6</file> and use different directories for
 477         packaged modules to <package>perl</package>:
 478         <example>
 479 /usr/lib/perl6
 480 /usr/share/perl6
 481         </example>
 482         This will allow Perl 5 and 6 packages and modules (which should
 483         be packaged as <package>libfoo-bar-perl6</package>), to co-exist
 484         for as long as required.
 485       </p>
 486       <p>
 487         At some stage in the future when Perl 6 is sufficiently mature,
 488         the package naming may be reversed such that the
 489         <package>perl</package> package contains Perl 6 and the current
 490         package becomes <package>perl5</package>.
 491       </p>
 492     </appendix>
 493   </book>
 494 </debiandoc>
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