


Module::Load::ConPerloProgrammers ReModule::Load::Conditional(3p)


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}\n";
           print "LWP is installed as file $rv->{file}\n";


           print "LWP requires the following modules to be installed:\n";
           print join "\n", 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.





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Module::Load::ConPerloProgrammers ReModule::Load::Conditional(3p)


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.

   $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



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Module::Load::ConPerloProgrammers ReModule::Load::Conditional(3p)


       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.



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Module::Load::ConPerloProgrammers ReModule::Load::Conditional(3p)


       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".

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.














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