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Perl Documentation


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 Encode).

Currently the first argument to define_alias() can be specified in the following ways:

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


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, Encode::Supported