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.
";
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}" string "CHARNAME" is first looked in the list of standard Unicode names of chars. 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}".
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:
use charnames (); # for $charnames::hint_bits
sub import {
shift;
$^H |= $charnames::hint_bits;
$^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(@_);
}
}
CUSTOM ALIASES
This version of charnames supports three mechanisms of adding local or customized aliases to standard Unicode naming conventions (:full)
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.
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.
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 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.
perl v5.8.0 2002-06-01 charnames(3pm)