mingw/html/lib/charnames.html

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  13 <big><strong><span class="block">&nbsp;charnames - define character names for C&lt;\N{named}&gt; string literal escapes</span></strong></big>
  14 </td></tr>
  15 </table>
  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="#synopsis">SYNOPSIS</a></li>
  24         <li><a href="#description">DESCRIPTION</a></li>
  25         <li><a href="#custom_translators">CUSTOM TRANSLATORS</a></li>
  26         <li><a href="#custom_aliases">CUSTOM ALIASES</a></li>
  27         <ul>
  28
  29                 <li><a href="#anonymous_hashes">Anonymous hashes</a></li>
  30                 <li><a href="#alias_file">Alias file</a></li>
  31                 <li><a href="#alias_shortcut">Alias shortcut</a></li>
  32         </ul>
  33
  34         <li><a href="#charnames__viacode_code_">charnames::viacode(code)</a></li>
  35         <li><a href="#charnames__vianame_name_">charnames::vianame(name)</a></li>
  36         <li><a href="#aliases">ALIASES</a></li>
  37         <li><a href="#illegal_characters">ILLEGAL CHARACTERS</a></li>
  38         <li><a href="#bugs">BUGS</a></li>
  39 </ul>
  40 <!-- INDEX END -->
  41
  42 <hr />
  43 <p>
  44 </p>
  45 <h1><a name="name">NAME</a></h1>
  46 <p>charnames - define character names for <code>\N{named}</code> string literal escapes</p>
  47 <p>
  48 </p>
  49 <hr />
  50 <h1><a name="synopsis">SYNOPSIS</a></h1>
  51 <pre>
  52   use charnames ':full';
  53   print &quot;\N{GREEK SMALL LETTER SIGMA} is called sigma.\n&quot;;</pre>
  54 <pre>
  55   use charnames ':short';
  56   print &quot;\N{greek:Sigma} is an upper-case sigma.\n&quot;;</pre>
  57 <pre>
  58   use charnames qw(cyrillic greek);
  59   print &quot;\N{sigma} is Greek sigma, and \N{be} is Cyrillic b.\n&quot;;</pre>
  60 <pre>
  61   use charnames &quot;:full&quot;, &quot;:alias&quot; =&gt; {
  62     e_ACUTE =&gt; &quot;LATIN SMALL LETTER E WITH ACUTE&quot;,
  63   };
  64   print &quot;\N{e_ACUTE} is a small letter e with an acute.\n&quot;;</pre>
  65 <pre>
  66   use charnames ();
  67   print charnames::viacode(0x1234); # prints &quot;ETHIOPIC SYLLABLE SEE&quot;
  68   printf &quot;%04X&quot;, charnames::vianame(&quot;GOTHIC LETTER AHSA&quot;); # prints &quot;10330&quot;</pre>
  69 <p>
  70 </p>
  71 <hr />
  72 <h1><a name="description">DESCRIPTION</a></h1>
  73 <p>Pragma <code>use charnames</code> supports arguments <code>:full</code>, <code>:short</code>, script
  74 names and customized aliases.  If <code>:full</code> is present, for expansion of
  75 <code>\N{CHARNAME}</code>, the string <code>CHARNAME</code> is first looked up in the list of
  76 standard Unicode character names.  If <code>:short</code> is present, and
  77 <code>CHARNAME</code> has the form <code>SCRIPT:CNAME</code>, then <code>CNAME</code> is looked up
  78 as a letter in script <code>SCRIPT</code>.  If pragma <code>use charnames</code> is used
  79 with script name arguments, then for <code>\N{CHARNAME}</code> the name
  80 <code>CHARNAME</code> is looked up as a letter in the given scripts (in the
  81 specified order). Customized aliases are explained in <a href="#custom_aliases">CUSTOM ALIASES</a>.</p>
  82 <p>For lookup of <code>CHARNAME</code> inside a given script <code>SCRIPTNAME</code>
  83 this pragma looks for the names</p>
  84 <pre>
  85   SCRIPTNAME CAPITAL LETTER CHARNAME
  86   SCRIPTNAME SMALL LETTER CHARNAME
  87   SCRIPTNAME LETTER CHARNAME</pre>
  88 <p>in the table of standard Unicode names.  If <code>CHARNAME</code> is lowercase,
  89 then the <code>CAPITAL</code> variant is ignored, otherwise the <code>SMALL</code> variant
  90 is ignored.</p>
  91 <p>Note that <code>\N{...}</code> is compile-time, it's a special form of string
  92 constant used inside double-quoted strings: in other words, you cannot
  93 use variables inside the <code>\N{...}</code>.  If you want similar run-time
  94 functionality, use charnames::vianame().</p>
  95 <p>For the C0 and C1 control characters (U+0000..U+001F, U+0080..U+009F)
  96 as of Unicode 3.1, there are no official Unicode names but you can use
  97 instead the ISO 6429 names (LINE FEED, ESCAPE, and so forth).  In
  98 Unicode 3.2 (as of Perl 5.8) some naming changes take place ISO 6429
  99 has been updated, see <a href="#aliases">ALIASES</a>.  Also note that the U+UU80, U+0081,
 100 U+0084, and U+0099 do not have names even in ISO 6429.</p>
 101 <p>Since the Unicode standard uses ``U+HHHH'', so can you: ``\N{U+263a}''
 102 is the Unicode smiley face, or ``\N{WHITE SMILING FACE}''.</p>
 103 <p>
 104 </p>
 105 <hr />
 106 <h1><a name="custom_translators">CUSTOM TRANSLATORS</a></h1>
 107 <p>The mechanism of translation of <code>\N{...}</code> escapes is general and not
 108 hardwired into <em>charnames.pm</em>.  A module can install custom
 109 translations (inside the scope which <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_use"><code>use</code></a>s the module) with the
 110 following magic incantation:</p>
 111 <pre>
 112     use charnames ();           # for $charnames::hint_bits
 113     sub import {
 114         shift;
 115         $^H |= $charnames::hint_bits;
 116         $^H{charnames} = \&amp;translator;
 117     }</pre>
 118 <p>Here <code>translator()</code> is a subroutine which takes <code>CHARNAME</code> as an
 119 argument, and returns text to insert into the string instead of the
 120 <code>\N{CHARNAME}</code> escape.  Since the text to insert should be different
 121 in <code>bytes</code> mode and out of it, the function should check the current
 122 state of <code>bytes</code>-flag as in:</p>
 123 <pre>
 124     use bytes ();                       # for $bytes::hint_bits
 125     sub translator {
 126         if ($^H &amp; $bytes::hint_bits) {
 127             return bytes_translator(@_);
 128         }
 129         else {
 130             return utf8_translator(@_);
 131         }
 132     }</pre>
 133 <p>
 134 </p>
 135 <hr />
 136 <h1><a name="custom_aliases">CUSTOM ALIASES</a></h1>
 137 <p>This version of charnames supports three mechanisms of adding local
 138 or customized aliases to standard Unicode naming conventions (:full)</p>
 139 <p>
 140 </p>
 141 <h2><a name="anonymous_hashes">Anonymous hashes</a></h2>
 142 <pre>
 143     use charnames &quot;:full&quot;, &quot;:alias&quot; =&gt; {
 144         e_ACUTE =&gt; &quot;LATIN SMALL LETTER E WITH ACUTE&quot;,
 145         };
 146     my $str = &quot;\N{e_ACUTE}&quot;;</pre>
 147 <p>
 148 </p>
 149 <h2><a name="alias_file">Alias file</a></h2>
 150 <pre>
 151     use charnames &quot;:full&quot;, &quot;:alias&quot; =&gt; &quot;pro&quot;;</pre>
 152 <pre>
 153     will try to read &quot;unicore/pro_alias.pl&quot; from the @INC path. This
 154     file should return a list in plain perl:</pre>
 155 <pre>
 156     (
 157     A_GRAVE         =&gt; &quot;LATIN CAPITAL LETTER A WITH GRAVE&quot;,
 158     A_CIRCUM        =&gt; &quot;LATIN CAPITAL LETTER A WITH CIRCUMFLEX&quot;,
 159     A_DIAERES       =&gt; &quot;LATIN CAPITAL LETTER A WITH DIAERESIS&quot;,
 160     A_TILDE         =&gt; &quot;LATIN CAPITAL LETTER A WITH TILDE&quot;,
 161     A_BREVE         =&gt; &quot;LATIN CAPITAL LETTER A WITH BREVE&quot;,
 162     A_RING          =&gt; &quot;LATIN CAPITAL LETTER A WITH RING ABOVE&quot;,
 163     A_MACRON        =&gt; &quot;LATIN CAPITAL LETTER A WITH MACRON&quot;,
 164     );</pre>
 165 <p>
 166 </p>
 167 <h2><a name="alias_shortcut">Alias shortcut</a></h2>
 168 <pre>
 169     use charnames &quot;:alias&quot; =&gt; &quot;:pro&quot;;</pre>
 170 <pre>
 171     works exactly the same as the alias pairs, only this time,
 172     &quot;:full&quot; is inserted automatically as first argument (if no
 173     other argument is given).</pre>
 174 <p>
 175 </p>
 176 <hr />
 177 <h1><a name="charnames__viacode_code_">charnames::viacode(code)</a></h1>
 178 <p>Returns the full name of the character indicated by the numeric code.
 179 The example</p>
 180 <pre>
 181     print charnames::viacode(0x2722);</pre>
 182 <p>prints ``FOUR TEARDROP-SPOKED ASTERISK''.</p>
 183 <p>Returns undef if no name is known for the code.</p>
 184 <p>This works only for the standard names, and does not yet apply
 185 to custom translators.</p>
 186 <p>Notice that the name returned for of U+FEFF is ``ZERO WIDTH NO-BREAK
 187 SPACE'', not ``BYTE ORDER MARK''.</p>
 188 <p>
 189 </p>
 190 <hr />
 191 <h1><a name="charnames__vianame_name_">charnames::vianame(name)</a></h1>
 192 <p>Returns the code point indicated by the name.
 193 The example</p>
 194 <pre>
 195     printf &quot;%04X&quot;, charnames::vianame(&quot;FOUR TEARDROP-SPOKED ASTERISK&quot;);</pre>
 196 <p>prints ``2722''.</p>
 197 <p>Returns undef if the name is unknown.</p>
 198 <p>This works only for the standard names, and does not yet apply
 199 to custom translators.</p>
 200 <p>
 201 </p>
 202 <hr />
 203 <h1><a name="aliases">ALIASES</a></h1>
 204 <p>A few aliases have been defined for convenience: instead of having
 205 to use the official names</p>
 206 <pre>
 207     LINE FEED (LF)
 208     FORM FEED (FF)
 209     CARRIAGE RETURN (CR)
 210     NEXT LINE (NEL)</pre>
 211 <p>(yes, with parentheses) one can use</p>
 212 <pre>
 213     LINE FEED
 214     FORM FEED
 215     CARRIAGE RETURN
 216     NEXT LINE
 217     LF
 218     FF
 219     CR
 220     NEL</pre>
 221 <p>One can also use</p>
 222 <pre>
 223     BYTE ORDER MARK
 224     BOM</pre>
 225 <p>and</p>
 226 <pre>
 227     ZWNJ
 228     ZWJ</pre>
 229 <p>for ZERO WIDTH NON-JOINER and ZERO WIDTH JOINER.</p>
 230 <p>For backward compatibility one can use the old names for
 231 certain C0 and C1 controls</p>
 232 <pre>
 233     old                         new</pre>
 234 <pre>
 235     HORIZONTAL TABULATION       CHARACTER TABULATION
 236     VERTICAL TABULATION         LINE TABULATION
 237     FILE SEPARATOR              INFORMATION SEPARATOR FOUR
 238     GROUP SEPARATOR             INFORMATION SEPARATOR THREE
 239     RECORD SEPARATOR            INFORMATION SEPARATOR TWO
 240     UNIT SEPARATOR              INFORMATION SEPARATOR ONE
 241     PARTIAL LINE DOWN           PARTIAL LINE FORWARD
 242     PARTIAL LINE UP             PARTIAL LINE BACKWARD</pre>
 243 <p>but the old names in addition to giving the character
 244 will also give a warning about being deprecated.</p>
 245 <p>
 246 </p>
 247 <hr />
 248 <h1><a name="illegal_characters">ILLEGAL CHARACTERS</a></h1>
 249 <p>If you ask by name for a character that does not exist, a warning is
 250 given and the Unicode <em>replacement character</em> ``\x{FFFD}'' is returned.</p>
 251 <p>If you ask by code for a character that does not exist, no warning is
 252 given and <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_undef"><code>undef</code></a> is returned.  (Though if you ask for a code point
 253 past U+10FFFF you do get a warning.)</p>
 254 <p>
 255 </p>
 256 <hr />
 257 <h1><a name="bugs">BUGS</a></h1>
 258 <p>Since evaluation of the translation function happens in a middle of
 259 compilation (of a string literal), the translation function should not
 260 do any <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_eval"><code>eval</code></a>s or <a href="file://C|\msysgit\mingw\html/pod/perlfunc.html#item_require"><code>require</code></a>s.  This restriction should be lifted in
 261 a future version of Perl.</p>
 262 <table border="0" width="100%" cellspacing="0" cellpadding="3">
 263 <tr><td class="block" style="background-color: #cccccc" valign="middle">
 264 <big><strong><span class="block">&nbsp;charnames - define character names for C&lt;\N{named}&gt; string literal escapes</span></strong></big>
 265 </td></tr>
 266 </table>
 267
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