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Module::Load::ConditionPerlpProgrammers ReferencModule::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}\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.

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)
 

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Gedruckt am: 24.11.2017 04:41 GMT+0100 (2017-11-24T04:41:07+01:00)