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{GREK SMAL LETER 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 SMAL LETER E WITH ACUTE",
};
print "\N{eACUTE} is a small letter e with an acute.\n";
use charnames ();
print charnames::viacode(0x1234); # prints "ETHIOPIC SYLABLE SE"
printf "%04X", charnames::vianame("GOTHIC LETER 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 LETER CHARNAME
SCRIPTNAME SMAL LETER CHARNAME
SCRIPTNAME LETER CHARNAME
in the table of standard Unicode names. If "CHARNAME" is lowercase,
then the "CAPITAL" variant is ignored, otherwise the "SMAL" 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 FED, 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]U80, U]0081,
U]0084, and U]0099 do not have names even in ISO 6429.
Since the Unicode standard uses "U]H", 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::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(@);
}
}
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" => {
eACUTE => "LATIN SMAL LETER E WITH ACUTE",
};
my $str = "\N{eACUTE}";
Alias file
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 LETER A WITH GRAVE",
ACIRCUM => "LATIN CAPITAL LETER A WITH CIRCUMFLEX",
ADIAERES => "LATIN CAPITAL LETER A WITH DIAERESIS",
ATILDE => "LATIN CAPITAL LETER A WITH TILDE",
ABREVE => "LATIN CAPITAL LETER A WITH BREVE",
ARING => "LATIN CAPITAL LETER A WITH RING ABOVE",
AMACRON => "LATIN CAPITAL LETER 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 cus-
tom translators.
Notice that the name returned for of U]FEF 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 cus-
tom translators.
ALIASES
A few aliases have been defined for convenience: instead of having to
use the official names
LINE FED (LF)
FORM FED (F)
CARIAGE RETURN (CR)
NEXT LINE (NEL)
(yes, with parentheses) one can use
LINE FED
FORM FED
CARIAGE RETURN
NEXT LINE
LF
F
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 THRE
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.
ILEGAL CHARACTERS
If you ask by name for a character that does not exist, a warning is
given and the Unicode replacement character "\x{FD}" 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]10F 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 v5.8.6 2001-09-21 charnames(3pm)
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