Variable::Alias - Alias any variable to any other variable
use Variable::Alias 'alias'; my $src; my $a; our $b; my @c; our @d; alias $src => $a; alias $a => $b; alias $b => $c; alias @c => @d; $src='src'; # All the other variables now have the string # 'src' in the appropriate places.
There are various ways to alias one variable to another in Perl. The most popular is by assigning to typeglobs. This is quite efective, but only works with globals. Another method is to use a module like
Devel::LexAlias, but as their names suggest, these only work with lexicals. There's no way to alias an element of an array or hash.
Variable::Alias changes all that. It uses a tie to provide One True Way to alias a variable.
Variable::Alias may export any or all of five functions. If you've used
Lexical::Alias, the interface is virtually identical.
aliastakes two variables of any type (scalar, array or hash) and aliases them. Make sure they have the sigil you want on the front.
This function is only available in Perl 5.8.0 and later, because the prototype tricks it uses were first implemented in that version.
alias_stakes two scalars and aliases them.
alias_atakes two arrays and aliases them. Note that this is actual arrays, not array elements, although you can alias references in elements, like so:
alias_htakes two hashes and aliases them.
alias_rtakes two references and aliases them. The referents must be of the same type.
If at some point you want to break the alias, just say
untie $variable. (The variable will not retain the value it had while aliased.)
Alias must be of the same type as the original
You tried to alias a variable of one type to a variable of another (e.g.
alias($scalar, @array)). You can't do that.
Can't alias type %s
You tried to alias a subroutine or a glob or something. This module only handles scalars, arrays, and hashes; everything else you might want to alias lives in a typeglob anyway.
Type of arg %s to %s must be %s (not %s)
This mouthful is generated by Perl; it means that you used e.g. a scalar with
alias_a. Make sure you're using the right
alias_Xvariant for the type you're aliasing, and that
Variable::Aliascan actually handle the type in question.
"Typeglobs and Filehandles" in perldata,
Lexical::Alias for information on other aliasing methods.
perltie for information on tying.
This'll be slow, because tied variables always are. Blech. If your aliasing needs are fairly simple, consider just using
Lexical::Alias or typeglobs--they'll be faster.
If you find any other bugs, drop me a note at <firstname.lastname@example.org>.
Brent Dax <email@example.com>
Copyright (C) 2002 Brent Dax <firstname.lastname@example.org>. All Rights Reserved.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.