NAME

       Encode::Alias - alias definitions to encodings

SYNOPSIS

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

DESCRIPTION

       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 Encode).

       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 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
           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
       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.

       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.

SEE ALSO

       Encode, Encode::Supported

perl v5.38.2                                       2025-04-08                               Encode::Alias(3perl)