Toby Inkster >
Module-Hash-0.001 >
Module::Hash

Module Version: 0.001
Module::Hash - a tied hash that requires modules for you

use strict; use Test::More tests => 1; use Module::Hash; tie my %MOD, "Module::Hash"; my $number = $MOD{"Math::BigInt"}->new(42); ok( $number->isa("Math::BigInt") );

Module::Hash provides a tied hash that can be used to load and quote module names.

tie my %MOD, "Module::Hash", %options;

The hash is tied to Module::Hash. Every time you fetch a hash key, such as `$MOD{"Math::BigInt"}`

that module is loaded, and the module name is returned as a string. Thus the following works without you needing to load Math::BigInt in advance.

$MOD{"Math::BigInt"}->new(...)

You may wonder what the advantage is of this hash, rather that using good old:

require Math::BigInt; Math::BigInt->new(...)

Well, the latter is actually ambiguous. Try defining a sub called `BigInt`

in the `Math`

package!

You can provide an optional minimum version number for the module. The module will be checked against the required version number, but the version number will not be included in the returned string. Thus the following works:

$MOD{"Math::BigInt 1.00"}->new(...)

The following options are supported:

**prefix**- an optional prefix for modulestie my $MATH, "Module::Hash", prefix => "Math"; my $number = $MATH{BigInt}->new(42);

**optimistic**- a boolean. If the hash is optimistic, then it doesn't croak when modules are missing; it silently returns the module name anyway. Hashes are optimistic by default; you need to explicitly pessimize them:tie my $MOD, "Module::Hash", optimistic => 0;

Attempting to modify the hash will croak.

If you just want to use the default options, you can supply a reference to the hash in the import statement:

my %MOD; use Module::Hash \%MOD; $MOD{"Math::BigInt"}->new(...);

Or:

my $MOD; use Module::Hash $MOD; $MOD->{"Math::BigInt"}->new(...);

Little known fact: Perl has a built-in global hash called `%\`

. Unlike `%+`

and `%-`

and some other built-in global hashes, the Perl core doesn't use it for anything. And I don't think anybody else uses it either. The following makes for some cute code...

use Module::Hash \%\; $\{"Math::BigInt"}->new(...);

... or an unmaintainable nightmare depending on your perspective.

This module also provides an object-oriented interface, intended for subclassing, etc, etc.

Methods:

Please report any bugs to http://rt.cpan.org/Dist/Display.html?Queue=Module-Hash.

Most of the tricky stuff is handled by Module::Runtime.

Module::Quote is similar to this, but more insane. If this module isn't insane enough for you, try that.

Toby Inkster <tobyink@cpan.org>.

This software is copyright (c) 2012 by Toby Inkster.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.

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