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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.\n";

use charnames ':short';

print "\N{greek:Sigma} is an upper-case sigma.\n";

use charnames qw(cyrillic greek);

print "\N{sigma} is Greek sigma, and \N{be} is Cyrillic b.\n";

use charnames ":full", ":alias" => {

eACUTE => "LATIN SMALL LETTER E WITH ACUTE", }; print "\N{eACUTE} is a small letter e with an acute.\n";

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 "CHAR-

NAME" has the form "SCRIPT:CNAME", then "CNAME" is looked up as a let-

ter 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). Cus-

tomized 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 con-

stant used inside double-quoted strings: in other words, you cannot use

variables inside the "\N{...}". If you want similar run-time function-

ality, 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 Uni-

code 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}". CCUUSSTTOOMM TTRRAANNSSLLAATTOORRSS 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:

use charnames (); # for $charnames::hintbits

sub import { shift;

$^H |= $charnames::hintbits;

$^H{charnames} = \&translator;

}

Here translator() is a subroutine which takes "CHARNAME" as an argu-

ment, 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::hintbits

sub translator {

if ($^H & $bytes::hintbits) {

return bytestranslator(@); } else { return utf8translator(@); } } CCUUSSTTOOMM AALLIIAASSEESS

This version of charnames supports three mechanisms of adding local or

customized aliases to standard Unicode naming conventions (:full) AAnnoonnyymmoouuss hhaasshheess

use charnames ":full", ":alias" => {

eACUTE => "LATIN SMALL LETTER E WITH ACUTE", };

my $str = "\N{eACUTE}";

AAlliiaass ffiillee

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

will try to read "unicore/proalias.pl" from the @INC path. This file should return a list in plain perl: ( AGRAVE => "LATIN CAPITAL LETTER A WITH GRAVE", ACIRCUM => "LATIN CAPITAL LETTER A WITH CIRCUMFLEX", ADIAERES => "LATIN CAPITAL LETTER A WITH DIAERESIS", ATILDE => "LATIN CAPITAL LETTER A WITH TILDE", ABREVE => "LATIN CAPITAL LETTER A WITH BREVE", ARING => "LATIN CAPITAL LETTER A WITH RING ABOVE", AMACRON => "LATIN CAPITAL LETTER A WITH MACRON", ); AAlliiaass sshhoorrttccuutt

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). cchhaarrnnaammeess::::vviiaaccooddee((ccooddee)) 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 cus-

tom translators.

Notice that the name returned for of U+FEFF is "ZERO WIDTH NO-BREAK

SPACE", not "BYTE ORDER MARK". cchhaarrnnaammeess::::vviiaannaammee((nnaammee)) 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 cus-

tom translators. AALLIIAASSEESS 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. IILLLLEEGGAALL CCHHAARRAACCTTEERRSS 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 does not exist, no warning is given and "undef" is returned. (Though if you ask for a code point past U+10FFFF you do get a warning.)

BUGS

Since evaluation of the translation function happens in a 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.