charnames(3pm)						 Perl Programmers Reference Guide					    charnames(3pm)

NAME

       charnames - define character names for "N{named}" string literal escapes

SYNOPSIS

	 use charnames ':full';
	 print "N{GREEK SMALL LETTER SIGMA} is called sigma.
";

	 use charnames ':short';
	 print "N{greek:Sigma} is an upper-case sigma.
";

	 use charnames qw(cyrillic greek);
	 print "N{sigma} is Greek sigma, and N{be} is Cyrillic b.
";

	 use charnames ":full", ":alias" => {
	   e_ACUTE => "LATIN SMALL LETTER E WITH ACUTE",
	 };
	 print "N{e_ACUTE} is a small letter e with an acute.
";

	 use charnames ();
	 print charnames::viacode(0x1234); # prints "ETHIOPIC SYLLABLE SEE"
	 printf "%04X", charnames::vianame("GOTHIC LETTER AHSA"); # prints "10330"

DESCRIPTION

       Pragma "use charnames" supports arguments ":full", ":short", script names and customized aliases.  If ":full" is present, for expansion of
       "N{CHARNAME}", the string "CHARNAME" is first looked up in the list of standard Unicode character names.  If ":short" is present, and
       "CHARNAME" has the form "SCRIPT:CNAME", then "CNAME" is looked up as a letter in script "SCRIPT".  If pragma "use charnames" is used with
       script name arguments, then for "N{CHARNAME}" the name "CHARNAME" is looked up as a letter in the given scripts (in the specified order).
       Customized aliases are explained in "CUSTOM ALIASES".

       For lookup of "CHARNAME" inside a given script "SCRIPTNAME" this pragma looks for the names

	 SCRIPTNAME CAPITAL LETTER CHARNAME
	 SCRIPTNAME SMALL LETTER CHARNAME
	 SCRIPTNAME LETTER CHARNAME

       in the table of standard Unicode names.	If "CHARNAME" is lowercase, then the "CAPITAL" variant is ignored, otherwise the "SMALL" variant
       is ignored.

       Note that "N{...}" is compile-time, it's a special form of string constant used inside double-quoted strings: in other words, you cannot
       use variables inside the "N{...}".  If you want similar run-time functionality, use charnames::vianame().

       For the C0 and C1 control characters (U+0000..U+001F, U+0080..U+009F) as of Unicode 3.1, there are no official Unicode names but you can
       use instead the ISO 6429 names (LINE FEED, ESCAPE, and so forth).  In Unicode 3.2 (as of Perl 5.8) some naming changes take place ISO 6429
       has been updated, see "ALIASES".  Also note that the U+UU80, U+0081, U+0084, and U+0099 do not have names even in ISO 6429.

       Since the Unicode standard uses "U+HHHH", so can you: "N{U+263a}" is the Unicode smiley face, or "N{WHITE SMILING FACE}".

ALIASES

       A few aliases have been defined for convenience: instead of having to use the official names

	   LINE FEED (LF)
	   FORM FEED (FF)
	   CARRIAGE RETURN (CR)
	   NEXT LINE (NEL)

       (yes, with parentheses) one can use

	   LINE FEED
	   FORM FEED
	   CARRIAGE RETURN
	   NEXT LINE
	   LF
	   FF
	   CR
	   NEL

       One can also use

	   BYTE ORDER MARK
	   BOM

       and

	   ZWNJ
	   ZWJ

       for ZERO WIDTH NON-JOINER and ZERO WIDTH JOINER.

       For backward compatibility one can use the old names for certain C0 and C1 controls

	   old			       new

	   HORIZONTAL TABULATION       CHARACTER TABULATION
	   VERTICAL TABULATION	       LINE TABULATION
	   FILE SEPARATOR	       INFORMATION SEPARATOR FOUR
	   GROUP SEPARATOR	       INFORMATION SEPARATOR THREE
	   RECORD SEPARATOR	       INFORMATION SEPARATOR TWO
	   UNIT SEPARATOR	       INFORMATION SEPARATOR ONE
	   PARTIAL LINE DOWN	       PARTIAL LINE FORWARD
	   PARTIAL LINE UP	       PARTIAL LINE BACKWARD

       but the old names in addition to giving the character will also give a warning about being deprecated.

CUSTOM ALIASES

       This version of charnames supports three mechanisms of adding local or customized aliases to standard Unicode naming conventions (:full).

       Note that an alias should not be something that is a legal curly brace-enclosed quantifier (see "QUANTIFIERS" in perlreref).  For example
       "N{123}" means to match 123 non-newline characters, and is not treated as an alias.  Aliases are discouraged from beginning with anything
       other than an alphabetic character and from containing anything other than alphanumerics, spaces, dashes, colons, parentheses, and
       underscores.  Currently they must be ASCII.

   Anonymous hashes
	   use charnames ":full", ":alias" => {
	       e_ACUTE => "LATIN SMALL LETTER E WITH ACUTE",
	       };
	   my $str = "N{e_ACUTE}";

   Alias file
	   use charnames ":full", ":alias" => "pro";

	   will try to read "unicore/pro_alias.pl" from the @INC path. This
	   file should return a list in plain perl:

	   (
	   A_GRAVE	   => "LATIN CAPITAL LETTER A WITH GRAVE",
	   A_CIRCUM	   => "LATIN CAPITAL LETTER A WITH CIRCUMFLEX",
	   A_DIAERES	   => "LATIN CAPITAL LETTER A WITH DIAERESIS",
	   A_TILDE	   => "LATIN CAPITAL LETTER A WITH TILDE",
	   A_BREVE	   => "LATIN CAPITAL LETTER A WITH BREVE",
	   A_RING	   => "LATIN CAPITAL LETTER A WITH RING ABOVE",
	   A_MACRON	   => "LATIN CAPITAL LETTER A WITH MACRON",
	   );

   Alias shortcut
	   use charnames ":alias" => ":pro";

	   works exactly the same as the alias pairs, only this time,
	   ":full" is inserted automatically as first argument (if no
	   other argument is given).

charnames::viacode(code)
       Returns the full name of the character indicated by the numeric code.  The example

	   print charnames::viacode(0x2722);

       prints "FOUR TEARDROP-SPOKED ASTERISK".

       Returns undef if no name is known for the code.

       This works only for the standard names, and does not yet apply to custom translators.

       Notice that the name returned for of U+FEFF is "ZERO WIDTH NO-BREAK SPACE", not "BYTE ORDER MARK".

charnames::vianame(name)
       Returns the code point indicated by the name.  The example

	   printf "%04X", charnames::vianame("FOUR TEARDROP-SPOKED ASTERISK");

       prints "2722".

       Returns undef if the name is unknown.

       This works only for the standard names, and does not yet apply to custom translators.

CUSTOM TRANSLATORS

       The mechanism of translation of "N{...}" escapes is general and not hardwired into charnames.pm.  A module can install custom translations
       (inside the scope which "use"s the module) with the following magic incantation:

	   sub import {
	       shift;
	       $^H{charnames} = &translator;
	   }

       Here translator() is a subroutine which takes "CHARNAME" as an argument, and returns text to insert into the string instead of the
       "N{CHARNAME}" escape.  Since the text to insert should be different in "bytes" mode and out of it, the function should check the current
       state of "bytes"-flag as in:

	   use bytes ();		       # for $bytes::hint_bits
	   sub translator {
	       if ($^H & $bytes::hint_bits) {
		   return bytes_translator(@_);
	       }
	       else {
		   return utf8_translator(@_);
	       }
	   }

       See "CUSTOM ALIASES" above for restrictions on "CHARNAME".

ILLEGAL CHARACTERS

       If you ask by name for a character that does not exist, a warning is given and the Unicode replacement character "x{FFFD}" is returned.

       If you ask by code for a character that is unassigned, no warning is given and "undef" is returned.  (Though if you ask for a code point
       past U+10FFFF you do get a warning.)  See "BUGS" below.

BUGS

       viacode should return an empty string for unassigned in-range Unicode code points, as that is their correct current name.

       viacode(0) doesn't return "NULL", but "undef"

       vianame returns a chr if the input name is of the form "U+...", and an ord otherwise.  It is planned to change this to always return an
       ord.

       None of the functions work on almost all the Hangul syllable and CJK Unicode characters that have their code points as part of their names.

       Names must be ASCII characters only.

       Unicode standard named sequences are not recognized, such as "LATIN CAPITAL LETTER A WITH MACRON AND GRAVE" (which should mean "LATIN
       CAPITAL LETTER A WITH MACRON" with an additional "COMBINING GRAVE ACCENT").

       Since evaluation of the translation function happens in the middle of compilation (of a string literal), the translation function should
       not do any "eval"s or "require"s.  This restriction should be lifted in a future version of Perl.

perl v5.12.1							    2010-05-13							    charnames(3pm)