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
18 $FIND_VERSION $ERROR $CHECK_INC_HASH];
25 @EXPORT_OK = qw[check_install can_load requires];
32 Module::Load::Conditional - Looking up module information / loading at runtime
36 use Module::Load::Conditional qw[can_load check_install requires];
42 'Test::More' => undef,
45 print can_load( modules => $use_list )
46 ? 'all modules loaded successfully'
47 : 'failed to load required modules';
50 my $rv = check_install( module => 'LWP', version => 5.60 )
51 or print 'LWP is not installed!';
53 print 'LWP up to date' if $rv->{uptodate};
54 print "LWP version is $rv->{version}\n";
55 print "LWP is installed as file $rv->{file}\n";
58 print "LWP requires the following modules to be installed:\n";
59 print join "\n", requires('LWP');
61 ### allow M::L::C to peek in your %INC rather than just
63 $Module::Load::Conditional::CHECK_INC_HASH = 1;
65 ### reset the 'can_load' cache
66 undef $Module::Load::Conditional::CACHE;
68 ### don't have Module::Load::Conditional issue warnings --
70 $Module::Load::Conditional::VERBOSE = 0;
72 ### The last error that happened during a call to 'can_load'
73 my $err = $Module::Load::Conditional::ERROR;
78 Module::Load::Conditional provides simple ways to query and possibly load any of
79 the modules you have installed on your system during runtime.
81 It is able to load multiple modules at once or none at all if one of
82 them was not able to load. It also takes care of any error checking
87 =head1 $href = check_install( module => NAME [, version => VERSION, verbose => BOOL ] );
89 C<check_install> allows you to verify if a certain module is installed
90 or not. You may call it with the following arguments:
96 The name of the module you wish to verify -- this is a required key
100 The version this module needs to be -- this is optional
104 Whether or not to be verbose about what it is doing -- it will default
105 to $Module::Load::Conditional::VERBOSE
109 It will return undef if it was not able to find where the module was
110 installed, or a hash reference with the following keys if it was able
117 Full path to the file that contains the module
121 The version number of the installed module - this will be C<undef> if
122 the module had no (or unparsable) version number, or if the variable
123 C<$Module::Load::Conditional::FIND_VERSION> was set to true.
124 (See the C<GLOBAL VARIABLES> section below for details)
128 A boolean value indicating whether or not the module was found to be
129 at least the version you specified. If you did not specify a version,
130 uptodate will always be true if the module was found.
131 If no parsable version was found in the module, uptodate will also be
132 true, since C<check_install> had no way to verify clearly.
138 ### this checks if a certain module is installed already ###
139 ### if it returns true, the module in question is already installed
140 ### or we found the file, but couldn't open it, OR there was no version
141 ### to be found in the module
142 ### it will return 0 if the version in the module is LOWER then the one
143 ### we are looking for, or if we couldn't find the desired module to begin with
144 ### if the installed version is higher or equal to the one we want, it will return
145 ### a hashref with he module name and version in it.. so 'true' as well.
150 version => { default => '0.0' },
151 module => { required => 1 },
152 verbose => { default => $VERBOSE },
156 unless( $args = check( $tmpl, \%hash, $VERBOSE ) ) {
157 warn loc( q[A problem occurred checking arguments] ) if $VERBOSE;
161 my $file = File::Spec->catfile( split /::/, $args->{module} ) . '.pm';
162 my $file_inc = File::Spec::Unix->catfile(
163 split /::/, $args->{module}
166 ### where we store the return value ###
175 ### check the inc hash if we're allowed to
176 if( $CHECK_INC_HASH ) {
177 $filename = $href->{'file'} =
178 $INC{ $file_inc } if defined $INC{ $file_inc };
180 ### find the version by inspecting the package
181 if( defined $filename && $FIND_VERSION ) {
183 $href->{version} = ${ "$args->{module}"."::VERSION" };
187 ### we didnt find the filename yet by looking in %INC,
189 unless( $filename ) {
191 DIR: for my $dir ( @INC ) {
196 ### @INC hook -- we invoke it and get the filehandle back
197 ### this is actually documented behaviour as of 5.8 ;)
199 if (UNIVERSAL::isa($dir, 'CODE')) {
200 ($fh) = $dir->($dir, $file);
202 } elsif (UNIVERSAL::isa($dir, 'ARRAY')) {
203 ($fh) = $dir->[0]->($dir, $file, @{$dir}{1..$#{$dir}})
205 } elsif (UNIVERSAL::can($dir, 'INC')) {
206 ($fh) = $dir->INC->($dir, $file);
209 if (!UNIVERSAL::isa($fh, 'GLOB')) {
210 warn loc(q[Cannot open file '%1': %2], $file, $!)
215 $filename = $INC{$file_inc} || $file;
218 $filename = File::Spec->catfile($dir, $file);
219 next unless -e $filename;
221 $fh = new FileHandle;
222 if (!$fh->open($filename)) {
223 warn loc(q[Cannot open file '%1': %2], $file, $!)
229 ### files need to be in unix format under vms,
230 ### or they might be loaded twice
231 $href->{file} = ON_VMS
232 ? VMS::Filespec::unixify( $filename )
235 ### user wants us to find the version from files
236 if( $FIND_VERSION ) {
239 while (local $_ = <$fh> ) {
241 ### stolen from EU::MM_Unix->parse_version to address
242 ### #24062: "Problem with CPANPLUS 0.076 misidentifying
243 ### versions after installing Text::NSP 1.03" where a
244 ### VERSION mentioned in the POD was found before
245 ### the real $VERSION declaration.
246 $in_pod = /^=(?!cut)/ ? 1 : /^=cut/ ? 0 : $in_pod;
249 ### try to find a version declaration in this string.
250 my $ver = __PACKAGE__->_parse_version( $_ );
253 $href->{version} = $ver;
262 ### if we couldn't find the file, return undef ###
263 return unless defined $href->{file};
265 ### only complain if we're expected to find a version higher than 0.0 anyway
266 if( $FIND_VERSION and not defined $href->{version} ) {
267 { ### don't warn about the 'not numeric' stuff ###
270 ### if we got here, we didn't find the version
271 warn loc(q[Could not check version on '%1'], $args->{module} )
272 if $args->{verbose} and $args->{version} > 0;
274 $href->{uptodate} = 1;
277 ### don't warn about the 'not numeric' stuff ###
280 ### use qv(), as it will deal with developer release number
281 ### ie ones containing _ as well. This addresses bug report
282 ### #29348: Version compare logic doesn't handle alphas?
284 qv( $args->{version} ) <= qv( $href->{version} ) ? 1 : 0;
292 my $str = shift or return;
293 my $verbose = shift or 0;
295 ### skip commented out lines, they won't eval to anything.
296 return if $str =~ /^\s*#/;
298 ### the following regexp & eval statement comes from the
299 ### ExtUtils::MakeMaker source (EU::MM_Unix->parse_version)
300 ### Following #18892, which tells us the original
301 ### regex breaks under -T, we must modifiy it so
302 ### it captures the entire expression, and eval /that/
303 ### rather than $_, which is insecure.
305 if( $str =~ /(?<!\\)([\$*])(([\w\:\']*)\bVERSION)\b.*\=/ ) {
307 print "Evaluating: $str\n" if $verbose;
309 ### this creates a string to be eval'd, like:
310 # package Module::Load::Conditional::_version;
314 # $VERSION=undef; do {
315 # use version; $VERSION = qv('0.0.3');
319 package Module::Load::Conditional::_version;
328 print "Evaltext: $eval\n" if $verbose;
336 my $rv = defined $result ? $result : '0.0';
338 print( $@ ? "Error: $@\n" : "Result: $rv\n" ) if $verbose;
343 ### unable to find a version in this string
347 =head2 $bool = can_load( modules => { NAME => VERSION [,NAME => VERSION] }, [verbose => BOOL, nocache => BOOL] )
349 C<can_load> will take a list of modules, optionally with version
350 numbers and determine if it is able to load them. If it can load *ALL*
351 of them, it will. If one or more are unloadable, none will be loaded.
353 This is particularly useful if you have More Than One Way (tm) to
354 solve a problem in a program, and only wish to continue down a path
355 if all modules could be loaded, and not load them if they couldn't.
357 This function uses the C<load> function from Module::Load under the
360 C<can_load> takes the following arguments:
366 This is a hashref of module/version pairs. The version indicates the
367 minimum version to load. If no version is provided, any version is
368 assumed to be good enough.
372 This controls whether warnings should be printed if a module failed
374 The default is to use the value of $Module::Load::Conditional::VERBOSE.
378 C<can_load> keeps its results in a cache, so it will not load the
379 same module twice, nor will it attempt to load a module that has
380 already failed to load before. By default, C<can_load> will check its
381 cache, but you can override that by setting C<nocache> to true.
389 modules => { default => {}, strict_type => 1 },
390 verbose => { default => $VERBOSE },
391 nocache => { default => 0 },
396 unless( $args = check( $tmpl, \%hash, $VERBOSE ) ) {
397 $ERROR = loc(q[Problem validating arguments!]);
398 warn $ERROR if $VERBOSE;
402 ### layout of $CACHE:
407 ### file => /path/to/file,
411 $CACHE ||= {}; # in case it was undef'd
415 my $href = $args->{modules};
418 for my $mod ( keys %$href ) {
420 next if $CACHE->{$mod}->{usable} && !$args->{nocache};
422 ### else, check if the hash key is defined already,
423 ### meaning $mod => 0,
424 ### indicating UNSUCCESSFUL prior attempt of usage
426 ### use qv(), as it will deal with developer release number
427 ### ie ones containing _ as well. This addresses bug report
428 ### #29348: Version compare logic doesn't handle alphas?
429 if ( !$args->{nocache}
430 && defined $CACHE->{$mod}->{usable}
431 && (qv($CACHE->{$mod}->{version}||0) >= qv($href->{$mod}))
433 $error = loc( q[Already tried to use '%1', which was unsuccessful], $mod);
437 my $mod_data = check_install(
439 version => $href->{$mod}
442 if( !$mod_data or !defined $mod_data->{file} ) {
443 $error = loc(q[Could not find or check module '%1'], $mod);
444 $CACHE->{$mod}->{usable} = 0;
449 $CACHE->{$mod}->{$_} = $mod_data->{$_}
450 } qw[version file uptodate];
455 for my $mod ( @load ) {
457 if ( $CACHE->{$mod}->{uptodate} ) {
461 ### in case anything goes wrong, log the error, the fact
462 ### we tried to use this module and return 0;
465 $CACHE->{$mod}->{usable} = 0;
468 $CACHE->{$mod}->{usable} = 1;
471 ### module not found in @INC, store the result in
472 ### $CACHE and return 0
475 $error = loc(q[Module '%1' is not uptodate!], $mod);
476 $CACHE->{$mod}->{usable} = 0;
483 if( defined $error ) {
485 Carp::carp( loc(q|%1 [THIS MAY BE A PROBLEM!]|,$error) ) if $args->{verbose};
494 =head2 @list = requires( MODULE );
496 C<requires> can tell you what other modules a particular module
497 requires. This is particularly useful when you're intending to write
498 a module for public release and are listing its prerequisites.
500 C<requires> takes but one argument: the name of a module.
501 It will then first check if it can actually load this module, and
502 return undef if it can't.
503 Otherwise, it will return a list of modules and pragmas that would
504 have been loaded on the module's behalf.
506 Note: The list C<require> returns has originated from your current
507 perl and your current install.
514 unless( check_install( module => $who ) ) {
515 warn loc(q[You do not have module '%1' installed], $who) if $VERBOSE;
519 my $lib = join " ", map { qq["-I$_"] } @INC;
520 my $cmd = qq[$^X $lib -M$who -e"print(join(qq[\\n],keys(%INC)))"];
524 map { chomp; s|/|::|g; $_ }
533 =head1 Global Variables
535 The behaviour of Module::Load::Conditional can be altered by changing the
536 following global variables:
538 =head2 $Module::Load::Conditional::VERBOSE
540 This controls whether Module::Load::Conditional will issue warnings and
541 explanations as to why certain things may have failed. If you set it
542 to 0, Module::Load::Conditional will not output any warnings.
545 =head2 $Module::Load::Conditional::FIND_VERSION
547 This controls whether Module::Load::Conditional will try to parse
548 (and eval) the version from the module you're trying to load.
550 If you don't wish to do this, set this variable to C<false>. Understand
551 then that version comparisons are not possible, and Module::Load::Conditional
552 can not tell you what module version you have installed.
553 This may be desirable from a security or performance point of view.
554 Note that C<$FIND_VERSION> code runs safely under C<taint mode>.
558 =head2 $Module::Load::Conditional::CHECK_INC_HASH
560 This controls whether C<Module::Load::Conditional> checks your
561 C<%INC> hash to see if a module is available. By default, only
562 C<@INC> is scanned to see if a module is physically on your
563 filesystem, or avialable via an C<@INC-hook>. Setting this variable
564 to C<true> will trust any entries in C<%INC> and return them for
569 =head2 $Module::Load::Conditional::CACHE
571 This holds the cache of the C<can_load> function. If you explicitly
572 want to remove the current cache, you can set this variable to
575 =head2 $Module::Load::Conditional::ERROR
577 This holds a string of the last error that happened during a call to
578 C<can_load>. It is useful to inspect this when C<can_load> returns
587 Please report bugs or other issues to E<lt>bug-module-load-conditional@rt.cpan.orgE<gt>.
591 This module by Jos Boumans E<lt>kane@cpan.orgE<gt>.
595 This library is free software; you may redistribute and/or modify it
596 under the same terms as Perl itself.