Gurusamy Sarathy > perl-5.6.1 > charnames

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Source   Latest Release: perl-5.21.2

NAME ^

charnames - define character names for \N{named} string literal escape.

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";

DESCRIPTION ^

Pragma use charnames supports arguments :full, :short and script names. 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).

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.

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 uses 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(@_);
        }
    }

BUGS ^

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

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