Class::Load(3)

NAME
Class::Load - a working (require "Class::Name") and more

SYNOPSIS
    use Class::Load ':all';

    try_load_class('Class::Name')
        or plan skip_all => "Class::Name required to run these tests";

    load_class('Class::Name');

    is_class_loaded('Class::Name');

    my $baseclass = load_optional_class('Class::Name::MightExist')
        ? 'Class::Name::MightExist'
        : 'Class::Name::Default';

DESCRIPTION
"require EXPR" only accepts "Class/Name.pm" style module names, not "Class::Name". How frustrating! For that, we provide "load_class 'Class::Name'".

It's often useful to test whether a module can be loaded, instead of throwing an error when it's not available. For that, we provide "try_load_class 'Class::Name'".

Finally, sometimes we need to know whether a particular class has been loaded. Asking %INC is an option, but that will miss inner packages and any class for which the filename does not correspond to the package name. For that, we provide "is_class_loaded 'Class::Name'".

FUNCTIONS

  load_class Class::Name
"load_class" will load "Class::Name" or throw an error, much like "require".

If "Class::Name" is already loaded (checked with "is_class_loaded") then it will not try to load the class. This is useful when you have inner packages which "require" does not check.

  try_load_class Class::Name -> 0|1 =head2 try_load_class Class::Name -> (0|1, error message)
Returns 1 if the class was loaded, 0 if it was not. If the class was not loaded, the error will be returned as a second return value in list context.

Again, if "Class::Name" is already loaded (checked with "is_class_loaded") then it will not try to load the class. This is useful when you have inner packages which "require" does not check.

  is_class_loaded Class::Name -> 0|1
This uses a number of heuristics to determine if the class "Class::Name" is loaded. There heuristics were taken from Class::MOP's old pure-perl implementation.

  load_optional_class Class::Name -> 0|1
"load_optional_class" is a lot like "try_load_class", but also a lot like "load_class".

If the class exists, and it works, then it will return 1.

If the class doesn't exist, and it appears to not exist on disk either, it will return 0.

If the class exists on disk, but loading from disk results in an error ( ie: a syntax error ), then it will "croak" with that error.

This is useful for using if you want a fallback module system, ie:

    my $class = load_optional_class($foo) ? $foo : $default;

That way, if $foo does exist, but can't be loaded due to error, you won't get the behaviour of it simply not existing.

SEE ALSO

UNIVERSAL::require
    Adds a "require" method to "UNIVERSAL" so that you can say "Class::Name->require". I personally dislike the pollution.

Module::Load
    Supports "Class::Name" and "Class/Name.pm" formats, no "try_to_load" or "is_class_loaded".

Moose, Jifty, Prophet, etc
    This module was designed to be used anywhere you have "if (eval "require $module"; 1)", which occurs in many large projects.

AUTHOR
Shawn M Moore, "<sartak at bestpractical.com>"

The implementation of "is_class_loaded" has been taken from Class::MOP.

BUGS
Please report any bugs or feature requests to "bug-class-load at rt.cpan.org", or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Class-Load <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Class-Load>.

COPYRIGHT & LICENSE
Copyright 2008-2009 Best Practical Solutions.

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