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


       Encode::Alias - alias definitions to encodings


         use Encode;
         use Encode::Alias;
         define_alias( "newName" => ENCODING);
         define_alias( qr/.../ => ENCODING);
         define_alias( sub { return ENCODING if ...; } );


       Allows newName to be used as an alias for ENCODING. ENCODING may be
       either the name of an encoding or an encoding object (as described in

       Currently the first argument to define_alias() 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

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

           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
           ignored if provided.  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 this 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

         # 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


       to do so.  And


       gets the factory settings back.

       Note that define_alias() will not be able to override the canonical
       name of encodings. Encodings are first looked up by canonical name
       before potential aliases are tried.


       Encode(3), Encode::Supported(3)

perl v5.24.0                      2016-03-01                Encode::Alias(3pm)

perl 5.24 - Generated Sun Nov 6 10:51:43 CST 2016
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