MirOS Manual: Encode::Alias(3p)


ext::Encode::lib:PerloProgrammeerxst:R:Encode::lib::Encode::Alias(3p)

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 encoding 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;

perl v5.8.8                2005-02-05                           1

ext::Encode::lib:PerloProgrammeerxst:R:Encode::lib::Encode::Alias(3p)

       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                2005-02-05                           2

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