Module::Load::Conditional(3pm)				 Perl Programmers Reference Guide			    Module::Load::Conditional(3pm)

NAME

       Module::Load::Conditional - Looking up module information / loading at runtime

SYNOPSIS

	   use Module::Load::Conditional qw[can_load check_install requires];

	   my $use_list = {
		   CPANPLUS	   => 0.05,
		   LWP		   => 5.60,
		   'Test::More'    => undef,
	   };

	   print can_load( modules => $use_list )
		   ? 'all modules loaded successfully'
		   : 'failed to load required modules';

	   my $rv = check_install( module => 'LWP', version => 5.60 )
		       or print 'LWP is not installed!';

	   print 'LWP up to date' if $rv->{uptodate};
	   print "LWP version is $rv->{version}
";
	   print "LWP is installed as file $rv->{file}
";

	   print "LWP requires the following modules to be installed:
";
	   print join "
", requires('LWP');

	   ### allow M::L::C to peek in your %INC rather than just
	   ### scanning @INC
	   $Module::Load::Conditional::CHECK_INC_HASH = 1;

	   ### reset the 'can_load' cache
	   undef $Module::Load::Conditional::CACHE;

	   ### don't have Module::Load::Conditional issue warnings --
	   ### default is '1'
	   $Module::Load::Conditional::VERBOSE = 0;

	   ### The last error that happened during a call to 'can_load'
	   my $err = $Module::Load::Conditional::ERROR;

DESCRIPTION

       Module::Load::Conditional provides simple ways to query and possibly load any of the modules you have installed on your system during
       runtime.

       It is able to load multiple modules at once or none at all if one of them was not able to load. It also takes care of any error checking
       and so forth.

Methods
$href = check_install( module => NAME [, version => VERSION, verbose => BOOL ] );
       "check_install" allows you to verify if a certain module is installed or not. You may call it with the following arguments:

       module
	   The name of the module you wish to verify -- this is a required key

       version
	   The version this module needs to be -- this is optional

       verbose
	   Whether or not to be verbose about what it is doing -- it will default to $Module::Load::Conditional::VERBOSE

       It will return undef if it was not able to find where the module was installed, or a hash reference with the following keys if it was able
       to find the file:

       file
	   Full path to the file that contains the module

       dir Directory, or more exact the @INC entry, where the module was loaded from.

       version
	   The version number of the installed module - this will be "undef" if the module had no (or unparsable) version number, or if the
	   variable $Module::Load::Conditional::FIND_VERSION was set to true.  (See the "GLOBAL VARIABLES" section below for details)

       uptodate
	   A boolean value indicating whether or not the module was found to be at least the version you specified. If you did not specify a
	   version, uptodate will always be true if the module was found.  If no parsable version was found in the module, uptodate will also be
	   true, since "check_install" had no way to verify clearly.

	   See also $Module::Load::Conditional::DEPRECATED, which affects the outcome of this value.

   $bool = can_load( modules => { NAME => VERSION [,NAME => VERSION] }, [verbose => BOOL, nocache => BOOL] )
       "can_load" will take a list of modules, optionally with version numbers and determine if it is able to load them. If it can load *ALL* of
       them, it will. If one or more are unloadable, none will be loaded.

       This is particularly useful if you have More Than One Way (tm) to solve a problem in a program, and only wish to continue down a path if
       all modules could be loaded, and not load them if they couldn't.

       This function uses the "load" function from Module::Load under the hood.

       "can_load" takes the following arguments:

       modules
	   This is a hashref of module/version pairs. The version indicates the minimum version to load. If no version is provided, any version is
	   assumed to be good enough.

       verbose
	   This controls whether warnings should be printed if a module failed to load.  The default is to use the value of
	   $Module::Load::Conditional::VERBOSE.

       nocache
	   "can_load" keeps its results in a cache, so it will not load the same module twice, nor will it attempt to load a module that has
	   already failed to load before. By default, "can_load" will check its cache, but you can override that by setting "nocache" to true.

   @list = requires( MODULE );
       "requires" can tell you what other modules a particular module requires. This is particularly useful when you're intending to write a
       module for public release and are listing its prerequisites.

       "requires" takes but one argument: the name of a module.  It will then first check if it can actually load this module, and return undef if
       it can't.  Otherwise, it will return a list of modules and pragmas that would have been loaded on the module's behalf.

       Note: The list "require" returns has originated from your current perl and your current install.

Global Variables
       The behaviour of Module::Load::Conditional can be altered by changing the following global variables:

   $Module::Load::Conditional::VERBOSE
       This controls whether Module::Load::Conditional will issue warnings and explanations as to why certain things may have failed. If you set
       it to 0, Module::Load::Conditional will not output any warnings.  The default is 0;

   $Module::Load::Conditional::FIND_VERSION
       This controls whether Module::Load::Conditional will try to parse (and eval) the version from the module you're trying to load.

       If you don't wish to do this, set this variable to "false". Understand then that version comparisons are not possible, and
       Module::Load::Conditional can not tell you what module version you have installed.  This may be desirable from a security or performance
       point of view.  Note that $FIND_VERSION code runs safely under "taint mode".

       The default is 1;

   $Module::Load::Conditional::CHECK_INC_HASH
       This controls whether "Module::Load::Conditional" checks your %INC hash to see if a module is available. By default, only @INC is scanned
       to see if a module is physically on your filesystem, or avialable via an "@INC-hook". Setting this variable to "true" will trust any
       entries in %INC and return them for you.

       The default is 0;

   $Module::Load::Conditional::CACHE
       This holds the cache of the "can_load" function. If you explicitly want to remove the current cache, you can set this variable to "undef"

   $Module::Load::Conditional::ERROR
       This holds a string of the last error that happened during a call to "can_load". It is useful to inspect this when "can_load" returns
       "undef".

   $Module::Load::Conditional::DEPRECATED
       This controls whether "Module::Load::Conditional" checks if a dual-life core module has been deprecated. If this is set to true
       "check_install" will return false to "uptodate", if a dual-life module is found to be loaded from $Config{privlibexp}

       The default is 0;

See Also
       "Module::Load"

BUG REPORTS

       Please report bugs or other issues to <bug-module-load-conditional@rt.cpan.org>.

AUTHOR

       This module by Jos Boumans <kane@cpan.org>.

COPYRIGHT

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

perl v5.12.1							    2010-05-13					    Module::Load::Conditional(3pm)