ext::Encode::lib:PerloProgrammext::Encode::lib::Encode::Alias(3p)NAMEEncode::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:PerloProgrammext::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
