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Encode::Alias(3)       Perl Programmers Reference Guide       Encode::Alias(3)



NAME
       Encode::Alias - alias definitions to encodings

SYNOPSIS
         use Encode;
         use Encode::Alias;
         define_alias( newName => ENCODING);

DESCRIPTION
       Allows newName to be used as an alias for ENCODING. ENCODING may be either the name of an encoding or an encod-
       ing object (as described in Encode).

       Currently newName can be specified in the following ways:

       As a simple string.
       As a qr// compiled regular expression, e.g.:
             define_alias( qr/^iso8859-(\d+)$/i => '"iso-8859-$1"' );

           In this case, if ENCODING is not a reference, it is "eval"-ed in order to allow $1 etc. to be substituted.
           The example is one way to alias names as used in X11 fonts to the MIME names for the iso-8859-* family.
           Note the double quotes inside the single quotes.

           (or, you don't have to do this yourself because this example is predefined)

           If you are using a regex here, you have to use the quotes as shown or it won't work.  Also note that regex
           handling is tricky even for the experienced.  Use this feature with caution.

       As a code reference, e.g.:
             define_alias( sub {shift =~ /^iso8859-(\d+)$/i ? "iso-8859-$1" : undef } );

           The same effect as the example above in a different way.  The coderef takes the alias name as an argument
           and returns a canonical name on success or undef if not.  Note the second argument is not required.  Use
           this with even more caution than the regex version.

       Changes in code reference aliasing

       As of Encode 1.87, the older form

         define_alias( sub { return  /^iso8859-(\d+)$/i ? "iso-8859-$1" : undef } );

       no longer works.

       Encode up to 1.86 internally used "local $_" to implement ths older form.  But consider the code below;

         use Encode;
         $_ = "eeeee" ;
         while (/(e)/g) {
           my $utf = decode('aliased-encoding-name', $1);
           print "position:",pos,"\n";
         }

       Prior to Encode 1.86 this fails because of "local $_".

       Alias overloading

       You can override predefined aliases by simply applying define_alias().  The new alias is always evaluated
       first, and when necessary, define_alias() flushes the internal cache to make the new definition available.

         # redirect SHIFT_JIS to MS/IBM Code Page 932, which is a
         # superset of SHIFT_JIS

         define_alias( qr/shift.*jis$/i  => '"cp932"' );
         define_alias( qr/sjis$/i        => '"cp932"' );

       If you want to zap all predefined aliases, you can use

         Encode::Alias->undef_aliases;

       to do so.  And

         Encode::Alias->init_aliases;

       gets the factory settings back.

SEE ALSO
       Encode, Encode::Supported



perl v5.8.8                       2001-09-21                  Encode::Alias(3)