1 package Module::Load::Conditional;
6 use Params::Check qw[check];
7 use Locale::Maketext::Simple Style => 'gettext';
14 use constant ON_VMS => $^O eq 'VMS';
17 use vars qw[ $VERSION @ISA $VERBOSE $CACHE @EXPORT_OK $DEPRECATED
18 $FIND_VERSION $ERROR $CHECK_INC_HASH];
26 @EXPORT_OK = qw[check_install can_load requires];
33 Module::Load::Conditional - Looking up module information / loading at runtime
37 use Module::Load::Conditional qw[can_load check_install requires];
43 'Test::More' => undef,
46 print can_load( modules => $use_list )
47 ? 'all modules loaded successfully'
48 : 'failed to load required modules';
51 my $rv = check_install( module => 'LWP', version => 5.60 )
52 or print 'LWP is not installed!';
54 print 'LWP up to date' if $rv->{uptodate};
55 print "LWP version is $rv->{version}\n";
56 print "LWP is installed as file $rv->{file}\n";
59 print "LWP requires the following modules to be installed:\n";
60 print join "\n", requires('LWP');
62 ### allow M::L::C to peek in your %INC rather than just
64 $Module::Load::Conditional::CHECK_INC_HASH = 1;
66 ### reset the 'can_load' cache
67 undef $Module::Load::Conditional::CACHE;
69 ### don't have Module::Load::Conditional issue warnings --
71 $Module::Load::Conditional::VERBOSE = 0;
73 ### The last error that happened during a call to 'can_load'
74 my $err = $Module::Load::Conditional::ERROR;
79 Module::Load::Conditional provides simple ways to query and possibly load any of
80 the modules you have installed on your system during runtime.
82 It is able to load multiple modules at once or none at all if one of
83 them was not able to load. It also takes care of any error checking
88 =head1 $href = check_install( module => NAME [, version => VERSION, verbose => BOOL ] );
90 C<check_install> allows you to verify if a certain module is installed
91 or not. You may call it with the following arguments:
97 The name of the module you wish to verify -- this is a required key
101 The version this module needs to be -- this is optional
105 Whether or not to be verbose about what it is doing -- it will default
106 to $Module::Load::Conditional::VERBOSE
110 It will return undef if it was not able to find where the module was
111 installed, or a hash reference with the following keys if it was able
118 Full path to the file that contains the module
122 Directory, or more exact the C<@INC> entry, where the module was
127 The version number of the installed module - this will be C<undef> if
128 the module had no (or unparsable) version number, or if the variable
129 C<$Module::Load::Conditional::FIND_VERSION> was set to true.
130 (See the C<GLOBAL VARIABLES> section below for details)
134 A boolean value indicating whether or not the module was found to be
135 at least the version you specified. If you did not specify a version,
136 uptodate will always be true if the module was found.
137 If no parsable version was found in the module, uptodate will also be
138 true, since C<check_install> had no way to verify clearly.
140 See also C<$Module::Load::Conditional::DEPRECATED>, which affects
141 the outcome of this value.
147 ### this checks if a certain module is installed already ###
148 ### if it returns true, the module in question is already installed
149 ### or we found the file, but couldn't open it, OR there was no version
150 ### to be found in the module
151 ### it will return 0 if the version in the module is LOWER then the one
152 ### we are looking for, or if we couldn't find the desired module to begin with
153 ### if the installed version is higher or equal to the one we want, it will return
154 ### a hashref with he module name and version in it.. so 'true' as well.
159 version => { default => '0.0' },
160 module => { required => 1 },
161 verbose => { default => $VERBOSE },
165 unless( $args = check( $tmpl, \%hash, $VERBOSE ) ) {
166 warn loc( q[A problem occurred checking arguments] ) if $VERBOSE;
170 my $file = File::Spec->catfile( split /::/, $args->{module} ) . '.pm';
171 my $file_inc = File::Spec::Unix->catfile(
172 split /::/, $args->{module}
175 ### where we store the return value ###
184 ### check the inc hash if we're allowed to
185 if( $CHECK_INC_HASH ) {
186 $filename = $href->{'file'} =
187 $INC{ $file_inc } if defined $INC{ $file_inc };
189 ### find the version by inspecting the package
190 if( defined $filename && $FIND_VERSION ) {
192 $href->{version} = ${ "$args->{module}"."::VERSION" };
196 ### we didnt find the filename yet by looking in %INC,
198 unless( $filename ) {
200 DIR: for my $dir ( @INC ) {
205 ### @INC hook -- we invoke it and get the filehandle back
206 ### this is actually documented behaviour as of 5.8 ;)
208 if (UNIVERSAL::isa($dir, 'CODE')) {
209 ($fh) = $dir->($dir, $file);
211 } elsif (UNIVERSAL::isa($dir, 'ARRAY')) {
212 ($fh) = $dir->[0]->($dir, $file, @{$dir}{1..$#{$dir}})
214 } elsif (UNIVERSAL::can($dir, 'INC')) {
215 ($fh) = $dir->INC($file);
218 if (!UNIVERSAL::isa($fh, 'GLOB')) {
219 warn loc(q[Cannot open file '%1': %2], $file, $!)
224 $filename = $INC{$file_inc} || $file;
227 $filename = File::Spec->catfile($dir, $file);
228 next unless -e $filename;
230 $fh = new FileHandle;
231 if (!$fh->open($filename)) {
232 warn loc(q[Cannot open file '%1': %2], $file, $!)
238 ### store the directory we found the file in
241 ### files need to be in unix format under vms,
242 ### or they might be loaded twice
243 $href->{file} = ON_VMS
244 ? VMS::Filespec::unixify( $filename )
247 ### user wants us to find the version from files
248 if( $FIND_VERSION ) {
251 while ( my $line = <$fh> ) {
253 ### stolen from EU::MM_Unix->parse_version to address
254 ### #24062: "Problem with CPANPLUS 0.076 misidentifying
255 ### versions after installing Text::NSP 1.03" where a
256 ### VERSION mentioned in the POD was found before
257 ### the real $VERSION declaration.
258 $in_pod = $line =~ /^=(?!cut)/ ? 1 :
259 $line =~ /^=cut/ ? 0 :
263 ### try to find a version declaration in this string.
264 my $ver = __PACKAGE__->_parse_version( $line );
267 $href->{version} = $ver;
276 ### if we couldn't find the file, return undef ###
277 return unless defined $href->{file};
279 ### only complain if we're expected to find a version higher than 0.0 anyway
280 if( $FIND_VERSION and not defined $href->{version} ) {
281 { ### don't warn about the 'not numeric' stuff ###
284 ### if we got here, we didn't find the version
285 warn loc(q[Could not check version on '%1'], $args->{module} )
286 if $args->{verbose} and $args->{version} > 0;
288 $href->{uptodate} = 1;
291 ### don't warn about the 'not numeric' stuff ###
294 ### use qv(), as it will deal with developer release number
295 ### ie ones containing _ as well. This addresses bug report
296 ### #29348: Version compare logic doesn't handle alphas?
298 ### Update from JPeacock: apparently qv() and version->new
299 ### are different things, and we *must* use version->new
300 ### here, or things like #30056 might start happening
302 version->new( $args->{version} ) <= version->new( $href->{version} )
307 if ( $DEPRECATED and version->new($]) >= version->new('5.011') ) {
308 require Module::CoreList;
311 $href->{uptodate} = 0 if
312 exists $Module::CoreList::version{ 0+$] }{ $args->{module} } and
313 Module::CoreList::is_deprecated( $args->{module} ) and
314 $Config::Config{privlibexp} eq $href->{dir};
322 my $str = shift or return;
323 my $verbose = shift or 0;
325 ### skip commented out lines, they won't eval to anything.
326 return if $str =~ /^\s*#/;
328 ### the following regexp & eval statement comes from the
329 ### ExtUtils::MakeMaker source (EU::MM_Unix->parse_version)
330 ### Following #18892, which tells us the original
331 ### regex breaks under -T, we must modifiy it so
332 ### it captures the entire expression, and eval /that/
333 ### rather than $_, which is insecure.
334 my $taint_safe_str = do { $str =~ /(^.*$)/sm; $1 };
336 if( $str =~ /(?<!\\)([\$*])(([\w\:\']*)\bVERSION)\b.*\=/ ) {
338 print "Evaluating: $str\n" if $verbose;
340 ### this creates a string to be eval'd, like:
341 # package Module::Load::Conditional::_version;
345 # $VERSION=undef; do {
346 # use version; $VERSION = qv('0.0.3');
350 package Module::Load::Conditional::_version;
359 print "Evaltext: $eval\n" if $verbose;
367 my $rv = defined $result ? $result : '0.0';
369 print( $@ ? "Error: $@\n" : "Result: $rv\n" ) if $verbose;
374 ### unable to find a version in this string
378 =head2 $bool = can_load( modules => { NAME => VERSION [,NAME => VERSION] }, [verbose => BOOL, nocache => BOOL] )
380 C<can_load> will take a list of modules, optionally with version
381 numbers and determine if it is able to load them. If it can load *ALL*
382 of them, it will. If one or more are unloadable, none will be loaded.
384 This is particularly useful if you have More Than One Way (tm) to
385 solve a problem in a program, and only wish to continue down a path
386 if all modules could be loaded, and not load them if they couldn't.
388 This function uses the C<load> function from Module::Load under the
391 C<can_load> takes the following arguments:
397 This is a hashref of module/version pairs. The version indicates the
398 minimum version to load. If no version is provided, any version is
399 assumed to be good enough.
403 This controls whether warnings should be printed if a module failed
405 The default is to use the value of $Module::Load::Conditional::VERBOSE.
409 C<can_load> keeps its results in a cache, so it will not load the
410 same module twice, nor will it attempt to load a module that has
411 already failed to load before. By default, C<can_load> will check its
412 cache, but you can override that by setting C<nocache> to true.
420 modules => { default => {}, strict_type => 1 },
421 verbose => { default => $VERBOSE },
422 nocache => { default => 0 },
427 unless( $args = check( $tmpl, \%hash, $VERBOSE ) ) {
428 $ERROR = loc(q[Problem validating arguments!]);
429 warn $ERROR if $VERBOSE;
433 ### layout of $CACHE:
438 ### file => /path/to/file,
442 $CACHE ||= {}; # in case it was undef'd
446 my $href = $args->{modules};
449 for my $mod ( keys %$href ) {
451 next if $CACHE->{$mod}->{usable} && !$args->{nocache};
453 ### else, check if the hash key is defined already,
454 ### meaning $mod => 0,
455 ### indicating UNSUCCESSFUL prior attempt of usage
457 ### use qv(), as it will deal with developer release number
458 ### ie ones containing _ as well. This addresses bug report
459 ### #29348: Version compare logic doesn't handle alphas?
461 ### Update from JPeacock: apparently qv() and version->new
462 ### are different things, and we *must* use version->new
463 ### here, or things like #30056 might start happening
464 if ( !$args->{nocache}
465 && defined $CACHE->{$mod}->{usable}
466 && (version->new( $CACHE->{$mod}->{version}||0 )
467 >= version->new( $href->{$mod} ) )
469 $error = loc( q[Already tried to use '%1', which was unsuccessful], $mod);
473 my $mod_data = check_install(
475 version => $href->{$mod}
478 if( !$mod_data or !defined $mod_data->{file} ) {
479 $error = loc(q[Could not find or check module '%1'], $mod);
480 $CACHE->{$mod}->{usable} = 0;
485 $CACHE->{$mod}->{$_} = $mod_data->{$_}
486 } qw[version file uptodate];
491 for my $mod ( @load ) {
493 if ( $CACHE->{$mod}->{uptodate} ) {
497 ### in case anything goes wrong, log the error, the fact
498 ### we tried to use this module and return 0;
501 $CACHE->{$mod}->{usable} = 0;
504 $CACHE->{$mod}->{usable} = 1;
507 ### module not found in @INC, store the result in
508 ### $CACHE and return 0
511 $error = loc(q[Module '%1' is not uptodate!], $mod);
512 $CACHE->{$mod}->{usable} = 0;
519 if( defined $error ) {
521 Carp::carp( loc(q|%1 [THIS MAY BE A PROBLEM!]|,$error) ) if $args->{verbose};
530 =head2 @list = requires( MODULE );
532 C<requires> can tell you what other modules a particular module
533 requires. This is particularly useful when you're intending to write
534 a module for public release and are listing its prerequisites.
536 C<requires> takes but one argument: the name of a module.
537 It will then first check if it can actually load this module, and
538 return undef if it can't.
539 Otherwise, it will return a list of modules and pragmas that would
540 have been loaded on the module's behalf.
542 Note: The list C<require> returns has originated from your current
543 perl and your current install.
550 unless( check_install( module => $who ) ) {
551 warn loc(q[You do not have module '%1' installed], $who) if $VERBOSE;
555 my $lib = join " ", map { qq["-I$_"] } @INC;
556 my $cmd = qq[$^X $lib -M$who -e"print(join(qq[\\n],keys(%INC)))"];
560 map { chomp; s|/|::|g; $_ }
569 =head1 Global Variables
571 The behaviour of Module::Load::Conditional can be altered by changing the
572 following global variables:
574 =head2 $Module::Load::Conditional::VERBOSE
576 This controls whether Module::Load::Conditional will issue warnings and
577 explanations as to why certain things may have failed. If you set it
578 to 0, Module::Load::Conditional will not output any warnings.
581 =head2 $Module::Load::Conditional::FIND_VERSION
583 This controls whether Module::Load::Conditional will try to parse
584 (and eval) the version from the module you're trying to load.
586 If you don't wish to do this, set this variable to C<false>. Understand
587 then that version comparisons are not possible, and Module::Load::Conditional
588 can not tell you what module version you have installed.
589 This may be desirable from a security or performance point of view.
590 Note that C<$FIND_VERSION> code runs safely under C<taint mode>.
594 =head2 $Module::Load::Conditional::CHECK_INC_HASH
596 This controls whether C<Module::Load::Conditional> checks your
597 C<%INC> hash to see if a module is available. By default, only
598 C<@INC> is scanned to see if a module is physically on your
599 filesystem, or avialable via an C<@INC-hook>. Setting this variable
600 to C<true> will trust any entries in C<%INC> and return them for
605 =head2 $Module::Load::Conditional::CACHE
607 This holds the cache of the C<can_load> function. If you explicitly
608 want to remove the current cache, you can set this variable to
611 =head2 $Module::Load::Conditional::ERROR
613 This holds a string of the last error that happened during a call to
614 C<can_load>. It is useful to inspect this when C<can_load> returns
617 =head2 $Module::Load::Conditional::DEPRECATED
619 This controls whether C<Module::Load::Conditional> checks if
620 a dual-life core module has been deprecated. If this is set to
621 true C<check_install> will return false to C<uptodate>, if
622 a dual-life module is found to be loaded from C<$Config{privlibexp}>
632 Please report bugs or other issues to E<lt>bug-module-load-conditional@rt.cpan.orgE<gt>.
636 This module by Jos Boumans E<lt>kane@cpan.orgE<gt>.
640 This library is free software; you may redistribute and/or modify it
641 under the same terms as Perl itself.