Module...itional(3perl) Perl Programmers Reference GuideModule...itional(3perl)
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, autoload => 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 or the "autoload_remote" 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.
autoload
This controls whether imports the functions of a loaded modules to
the caller package. The default is no importing any functions.
See the "autoload" function and the "autoload_remote" function from
Module::Load for details.
@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 available 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::FORCE_SAFE_INC
This controls whether "Module::Load::Conditional" sanitises @INC by
removing ""."". The current default setting is 0, but this may change in
a future release.
$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 v5.40.1 2026-08-30 Module...itional(3perl)
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