3 Module::Build::API - API Reference for Module Authors
8 I list here some of the most important methods in C<Module::Build>.
9 Normally you won't need to deal with these methods unless you want to
10 subclass C<Module::Build>. But since one of the reasons I created
11 this module in the first place was so that subclassing is possible
12 (and easy), I will certainly write more docs as the interface
24 This method returns a reasonable facsimile of the currently-executing
25 C<Module::Build> object representing the current build. You can use
26 this object to query its L</notes()> method, inquire about installed
27 modules, and so on. This is a great way to share information between
28 different parts of your build process. For instance, you can ask
29 the user a question during C<perl Build.PL>, then use their answer
30 during a regression test:
33 my $color = $build->prompt("What is your favorite color?");
34 $build->notes(color => $color);
38 my $build = Module::Build->current;
39 my $color = $build->notes('color');
42 The way the C<current()> method is currently implemented, there may be
43 slight differences between the C<$build> object in Build.PL and the
44 one in C<t/colortest.t>. It is our goal to minimize these differences
45 in future releases of Module::Build, so please report any anomalies
48 One important caveat: in its current implementation, C<current()> will
49 B<NOT> work correctly if you have changed out of the directory that
50 C<Module::Build> was invoked from.
56 Creates a new Module::Build object. Arguments to the new() method are
57 listed below. Most arguments are optional, but you must provide
58 either the L</module_name> argument, or L</dist_name> and one of
59 L</dist_version> or L</dist_version_from>. In other words, you must
60 provide enough information to determine both a distribution name and
70 An array reference of files to be cleaned up when the C<clean> action
71 is performed. See also the L<add_to_cleanup()|/"add_to_cleanup(@files)">
78 This parameter supports the setting of features (see
79 L</feature($name)>) automatically based on a set of prerequisites. For
80 instance, for a module that could optionally use either MySQL or
81 PostgreSQL databases, you might use C<auto_features> like this:
83 my $build = Module::Build->new
85 ...other stuff here...
88 description => "Interface with Postgres databases",
89 requires => { 'DBD::Pg' => 23.3,
90 'DateTime::Format::Pg' => 0 },
93 description => "Interface with MySQL databases",
94 requires => { 'DBD::mysql' => 17.9,
95 'DateTime::Format::MySQL' => 0 },
100 For each feature named, the required prerequisites will be checked, and
101 if there are no failures, the feature will be enabled (set to C<1>).
102 Otherwise the failures will be displayed to the user and the feature
103 will be disabled (set to C<0>).
105 See the documentation for L</requires> for the details of how
106 requirements can be specified.
112 An optional C<autosplit> argument specifies a file which should be run
113 through the L<AutoSplit::autosplit()|AutoSplit/autosplit> function.
114 If multiple files should be split, the argument may be given as an
115 array of the files to split.
117 In general I don't consider autosplitting a great idea, because it's
118 not always clear that autosplitting achieves its intended performance
119 benefits. It may even harm performance in environments like mod_perl,
120 where as much as possible of a module's code should be loaded during
127 The Module::Build class or subclass to use in the build script.
128 Defaults to "Module::Build" or the class name passed to or created by
129 a call to L</subclass()>. This property is useful if you're
130 writing a custom Module::Build subclass and have a bootstrapping
131 problem--that is, your subclass requires modules that may not be
132 installed when C<perl Build.PL> is executed, but you've listed in
133 L</build_requires> so that they should be available when C<./Build> is
140 Modules listed in this section are necessary to build and install the
141 given module, but are not necessary for regular usage of it. This is
142 actually an important distinction - it allows for tighter control over
143 the body of installed modules, and facilitates correct dependency
144 checking on binary/packaged distributions of the module.
146 See the documentation for L<Module::Build::Authoring/"PREREQUISITES">
147 for the details of how requirements can be specified.
149 =item create_packlist
153 If true, this parameter tells Module::Build to create a F<.packlist>
154 file during the C<install> action, just like ExtUtils::MakeMaker does.
155 The file is created in a subdirectory of the C<arch> installation
156 location. It is used by some other tools (CPAN, CPANPLUS, etc.) for
157 determining what files are part of an install.
159 The default value is true. This parameter was introduced in
160 Module::Build version 0.2609; previously no packlists were ever
161 created by Module::Build.
167 An optional C<c_source> argument specifies a directory which contains
168 C source files that the rest of the build may depend on. Any C<.c>
169 files in the directory will be compiled to object files. The
170 directory will be added to the search path during the compilation and
171 linking phases of any C or XS files.
177 Modules listed in this section conflict in some serious way with the
178 given module. C<Module::Build> (or some higher-level tool) will
179 refuse to install the given module if the given module/version is also
182 See the documentation for L<Module::Build::Authoring/"PREREQUISITES">
183 for the details of how requirements can be specified.
185 =item create_makefile_pl
189 This parameter lets you use Module::Build::Compat during the
190 C<distdir> (or C<dist>) action to automatically create a Makefile.PL
191 for compatibility with ExtUtils::MakeMaker. The parameter's value
192 should be one of the styles named in the L<Module::Build::Compat>
199 This parameter tells Module::Build to automatically create a F<README>
200 file at the top level of your distribution. Currently it will simply
201 use C<Pod::Text> (or C<Pod::Readme> if it's installed) on the file
202 indicated by C<dist_version_from> and put the result in the F<README>
203 file. This is by no means the only recommended style for writing a
204 README, but it seems to be one common one used on the CPAN.
206 If you generate a F<README> in this way, it's probably a good idea to
207 create a separate F<INSTALL> file if that information isn't in the
214 This should be a short description of the distribution. This is used
215 when generating metadata for F<META.yml> and PPD files. If it is not
216 given then C<Module::Build> looks in the POD of the module from which
217 it gets the distribution's version. It looks for the first line
218 matching C<$package\s-\s(.+)>, and uses the captured text as the
225 This should be something like "John Doe <jdoe@example.com>", or if
226 there are multiple authors, an anonymous array of strings may be
227 specified. This is used when generating metadata for F<META.yml> and
228 PPD files. If this is not specified, then C<Module::Build> looks at
229 the module from which it gets the distribution's version. If it finds
230 a POD section marked "=head1 AUTHOR", then it uses the contents of
237 Specifies the name for this distribution. Most authors won't need to
238 set this directly, they can use C<module_name> to set C<dist_name> to
239 a reasonable default. However, some agglomerative distributions like
240 C<libwww-perl> or C<bioperl> have names that don't correspond directly
241 to a module name, so C<dist_name> can be set independently.
247 Specifies a version number for the distribution. See L</module_name>
248 or L</dist_version_from> for ways to have this set automatically from a
249 C<$VERSION> variable in a module. One way or another, a version
250 number needs to be set.
252 =item dist_version_from
256 Specifies a file to look for the distribution version in. Most
257 authors won't need to set this directly, they can use L</module_name>
258 to set it to a reasonable default.
260 The version is extracted from the specified file according to the same
261 rules as L<ExtUtils::MakeMaker> and C<CPAN.pm>. It involves finding
262 the first line that matches the regular expression
264 /([\$*])(([\w\:\']*)\bVERSION)\b.*\=/
266 eval()-ing that line, then checking the value of the C<$VERSION>
267 variable. Quite ugly, really, but all the modules on CPAN depend on
268 this process, so there's no real opportunity to change to something
275 A boolean flag indicating whether the F<Build.PL> file must be
276 executed, or whether this module can be built, tested and installed
277 solely from consulting its metadata file. The main reason to set this
278 to a true value is that your module performs some dynamic
279 configuration as part of its build/install process. If the flag is
280 omitted, the F<META.yml> spec says that installation tools should
281 treat it as 1 (true), because this is a safer way to behave.
283 Currently C<Module::Build> doesn't actually do anything with this flag
284 - it's up to higher-level tools like C<CPAN.pm> to do something useful
285 with it. It can potentially bring lots of security, packaging, and
286 convenience improvements.
288 =item extra_compiler_flags
290 =item extra_linker_flags
294 These parameters can contain array references (or strings, in which
295 case they will be split into arrays) to pass through to the compiler
296 and linker phases when compiling/linking C code. For example, to tell
297 the compiler that your code is C++, you might do:
299 my $build = Module::Build->new
301 module_name => 'Foo::Bar',
302 extra_compiler_flags => ['-x', 'c++'],
305 To link your XS code against glib you might write something like:
307 my $build = Module::Build->new
309 module_name => 'Foo::Bar',
311 extra_compiler_flags => scalar `glib-config --cflags`,
312 extra_linker_flags => scalar `glib-config --libs`,
319 You can pass arbitrary command line options to F<Build.PL> or
320 F<Build>, and they will be stored in the Module::Build object and can
321 be accessed via the L</args()> method. However, sometimes you want
322 more flexibility out of your argument processing than this allows. In
323 such cases, use the C<get_options> parameter to pass in a hash
324 reference of argument specifications, and the list of arguments to
325 F<Build.PL> or F<Build> will be processed according to those
326 specifications before they're passed on to C<Module::Build>'s own
329 The supported option specification hash keys are:
336 The type of option. The types are those supported by Getopt::Long; consult
337 its documentation for a complete list. Typical types are C<=s> for strings,
338 C<+> for additive options, and C<!> for negatable options. If the
339 type is not specified, it will be considered a boolean, i.e. no
340 argument is taken and a value of 1 will be assigned when the option is
345 A reference to a scalar in which to store the value passed to the option.
346 If not specified, the value will be stored under the option name in the
347 hash returned by the C<args()> method.
351 A default value for the option. If no default value is specified and no option
352 is passed, then the option key will not exist in the hash returned by
358 You can combine references to your own variables or subroutines with
359 unreferenced specifications, for which the result will also be stored in the
360 hash returned by C<args()>. For example:
363 my $build = Module::Build->new
365 module_name => 'Foo::Bar',
367 loud => { store => \$loud },
368 dbd => { type => '=s' },
369 quantity => { type => '+' },
373 print STDERR "HEY, ARE YOU LISTENING??\n" if $loud;
374 print "We'll use the ", $build->args('dbd'), " DBI driver\n";
375 print "Are you sure you want that many?\n"
376 if $build->args('quantity') > 2;
378 The arguments for such a specification can be called like so:
380 perl Build.PL --loud --dbd=DBD::pg --quantity --quantity --quantity
382 B<WARNING:> Any option specifications that conflict with Module::Build's own
383 options (defined by its properties) will throw an exception.
385 Consult the Getopt::Long documentation for details on its usage.
391 Specifies any additional directories in which to search for C header
392 files. May be given as a string indicating a single directory, or as
393 a list reference indicating multiple directories.
399 You can set paths for individual installable elements by using the
400 C<install_path> parameter:
402 my $build = Module::Build->new
404 ...other stuff here...
407 arch => '/foo/lib/arch',
415 Determines where files are installed within the normal perl hierarchy
416 as determined by F<Config.pm>. Valid values are: C<core>, C<site>,
417 C<vendor>. The default is C<site>. See
418 L<Module::Build/"INSTALL PATHS">
424 Specifies the licensing terms of your distribution. Valid options include:
431 The distribution is licensed under the Apache Software License
432 (L<http://opensource.org/licenses/apachepl.php>).
436 The distribution is licensed under the Artistic License, as specified
437 by the F<Artistic> file in the standard Perl distribution.
441 The distribution is licensed under the Artistic 2.0 License
442 (L<http://opensource.org/licenses/artistic-license-2.0.php>.)
446 The distribution is licensed under the BSD License
447 (L<http://www.opensource.org/licenses/bsd-license.php>).
451 The distribution is licensed under the terms of the GNU General
452 Public License (L<http://www.opensource.org/licenses/gpl-license.php>).
456 The distribution is licensed under the terms of the GNU Lesser
457 General Public License
458 (L<http://www.opensource.org/licenses/lgpl-license.php>).
462 The distribution is licensed under the MIT License
463 (L<http://opensource.org/licenses/mit-license.php>).
467 The distribution is licensed under the Mozilla Public
468 License. (L<http://opensource.org/licenses/mozilla1.0.php> or
469 L<http://opensource.org/licenses/mozilla1.1.php>)
473 The distribution is licensed under some other Open Source
474 Initiative-approved license listed at
475 L<http://www.opensource.org/licenses/>.
479 The distribution may be copied and redistributed under the same terms
480 as Perl itself (this is by far the most common licensing option for
481 modules on CPAN). This is a dual license, in which the user may
482 choose between either the GPL or the Artistic license.
486 The distribution may not be redistributed without special permission
487 from the author and/or copyright holder.
491 The distribution is licensed under a license that is B<not> approved
492 by www.opensource.org but that allows distribution without
498 Note that you must still include the terms of your license in your
499 documentation - this field only lets automated tools figure out your
500 licensing restrictions. Humans still need something to read. If you
501 choose to provide this field, you should make sure that you keep it in
502 sync with your written documentation if you ever change your licensing
505 You may also use a license type of C<unknown> if you don't wish to
506 specify your terms in the metadata.
508 It is a fatal error to use a license other than the ones mentioned
509 above. This is not because I wish to impose licensing terms on you -
510 please let me know if you would like another license option to be
511 added to the list. I just started out with a small set of licenses to
512 keep things simple, figuring I'd let people with actual working
513 knowledge in this area tell me what to do. So if that's you, drop me
520 A hash of key/value pairs that should be added to the F<META.yml> file
521 during the C<distmeta> action. Any existing entries with the same
522 names will be overridden.
524 See the L</"MODULE METADATA"> section for details.
530 A hash of key/value pairs that should be merged into the F<META.yml>
531 file during the C<distmeta> action. Any existing entries with the
532 same names will be overridden.
534 The only difference between C<meta_add> and C<meta_merge> is their
535 behavior on hash-valued and array-valued entries: C<meta_add> will
536 completely blow away the existing hash or array value, but
537 C<meta_merge> will merge the supplied data into the existing hash or
540 See the L</"MODULE METADATA"> section for details.
546 The C<module_name> is a shortcut for setting default values of
547 C<dist_name> and C<dist_version_from>, reflecting the fact that the
548 majority of CPAN distributions are centered around one "main" module.
549 For instance, if you set C<module_name> to C<Foo::Bar>, then
550 C<dist_name> will default to C<Foo-Bar> and C<dist_version_from> will
551 default to C<lib/Foo/Bar.pm>. C<dist_version_from> will in turn be
552 used to set C<dist_version>.
554 Setting C<module_name> won't override a C<dist_*> parameter you
561 An optional parameter specifying a set of C<.PL> files in your
562 distribution. These will be run as Perl scripts prior to processing
563 the rest of the files in your distribution. They are usually used as
564 templates for creating other files dynamically, so that a file like
565 C<lib/Foo/Bar.pm.PL> might create the file C<lib/Foo/Bar.pm>.
567 The files are specified with the C<.PL> files as hash keys, and the
568 file(s) they generate as hash values, like so:
570 my $build = Module::Build->new
572 module_name => 'Foo::Bar',
574 PL_files => { 'lib/Foo/Bar.pm.PL' => 'lib/Foo/Bar.pm' },
577 Note that the path specifications are I<always> given in Unix-like
578 format, not in the style of the local system.
580 If your C<.PL> scripts don't create any files, or if they create files
581 with unexpected names, or even if they create multiple files, you can
582 indicate that so that Module::Build can properly handle these created
586 'lib/Foo/Bar.pm.PL' => 'lib/Foo/Bar.pm',
587 'lib/something.PL' => ['/lib/something', '/lib/else'],
588 'lib/funny.PL' => [],
595 An optional parameter specifying the set of C<.pm> files in this
596 distribution, specified as a hash reference whose keys are the files'
597 locations in the distributions, and whose values are their logical
598 locations based on their package name, i.e. where they would be found
599 in a "normal" Module::Build-style distribution. This parameter is
600 mainly intended to support alternative layouts of files.
602 For instance, if you have an old-style MakeMaker distribution for a
603 module called C<Foo::Bar> and a F<Bar.pm> file at the top level of the
604 distribution, you could specify your layout in your C<Build.PL> like
607 my $build = Module::Build->new
609 module_name => 'Foo::Bar',
611 pm_files => { 'Bar.pm' => 'lib/Foo/Bar.pm' },
614 Note that the values should include C<lib/>, because this is where
615 they would be found in a "normal" Module::Build-style distribution.
617 Note also that the path specifications are I<always> given in
618 Unix-like format, not in the style of the local system.
624 Just like C<pm_files>, but used for specifying the set of C<.pod>
625 files in your distribution.
631 This is just like the L</requires> argument, except that modules listed
632 in this section aren't essential, just a good idea. We'll just print
633 a friendly warning if one of these modules aren't found, but we'll
636 If a module is recommended but not required, all tests should still
637 pass if the module isn't installed. This may mean that some tests
638 may be skipped if recommended dependencies aren't present.
640 Automated tools like CPAN.pm should inform the user when recommended
641 modules aren't installed, and it should offer to install them if it
644 See the documentation for L<Module::Build::Authoring/"PREREQUISITES">
645 for the details of how requirements can be specified.
647 =item recursive_test_files
651 Normally, C<Module::Build> does not search subdirectories when looking
652 for tests to run. When this options is set it will search recursively
653 in all subdirectories of the standard 't' test directory.
659 An optional C<requires> argument specifies any module prerequisites
660 that the current module depends on.
662 One note: currently C<Module::Build> doesn't actually I<require> the
663 user to have dependencies installed, it just strongly urges. In the
664 future we may require it. There's also a L</recommends> section for
665 things that aren't absolutely required.
667 Automated tools like CPAN.pm should refuse to install a module if one
668 of its dependencies isn't satisfied, unless a "force" command is given
669 by the user. If the tools are helpful, they should also offer to
670 install the dependencies.
672 A synonym for C<requires> is C<prereq>, to help succour people
673 transitioning from C<ExtUtils::MakeMaker>. The C<requires> term is
674 preferred, but the C<prereq> term will remain valid in future
677 See the documentation for L<Module::Build::Authoring/"PREREQUISITES">
678 for the details of how requirements can be specified.
684 An optional parameter specifying a set of files that should be
685 installed as executable Perl scripts when the module is installed.
686 May be given as an array reference of the files, as a hash reference
687 whose keys are the files (and whose values will currently be ignored),
688 as a string giving the name of a directory in which to find scripts,
689 or as a string giving the name of a single script file.
691 The default is to install any scripts found in a F<bin> directory at
692 the top level of the distribution.
694 For backward compatibility, you may use the parameter C<scripts>
695 instead of C<script_files>. Please consider this usage deprecated,
696 though it will continue to exist for several version releases.
702 If a true value is specified for this parameter, L<Module::Signature>
703 will be used (via the 'distsign' action) to create a SIGNATURE file
704 for your distribution during the 'distdir' action, and to add the
705 SIGNATURE file to the MANIFEST (therefore, don't add it yourself).
707 The default value is false. In the future, the default may change to
708 true if you have C<Module::Signature> installed on your system.
714 An optional parameter specifying a set of files that should be used as
715 C<Test::Harness>-style regression tests to be run during the C<test>
716 action. May be given as an array reference of the files, or as a hash
717 reference whose keys are the files (and whose values will currently be
718 ignored). If the argument is given as a single string (not in an
719 array reference), that string will be treated as a C<glob()> pattern
720 specifying the files to use.
722 The default is to look for a F<test.pl> script in the top-level
723 directory of the distribution, and any files matching the glob pattern
724 C<*.t> in the F<t/> subdirectory. If the C<recursive_test_files>
725 property is true, then the C<t/> directory will be scanned recursively
728 =item use_tap_harness
732 An optional parameter indicating whether or not to use TAP::Harness for
733 testing rather than Test::Harness. Defaults to false. If set to true, you must
734 therefore be sure to add TAP::Harness as a requirement for your module in
735 L</build_requires>. Implicitly set to a true value if C<tap_harness_args> is
738 =item tap_harness_args
742 An optional parameter specifying parameters to be passed to TAP::Harness when
743 running tests. Must be given as a hash reference of parameters; see the
744 L<TAP::Harness|TAP::Harness> documentation for details. Note that specifying
745 this parameter will implicitly set C<use_tap_harness> to a true value. You
746 must therefore be sure to add TAP::Harness as a requirement for your module in
753 Just like C<pm_files>, but used for specifying the set of C<.xs>
754 files in your distribution.
759 =item new_from_context(%args)
763 When called from a directory containing a F<Build.PL> script and a
764 F<META.yml> file (in other words, the base directory of a
765 distribution), this method will run the F<Build.PL> and return the
766 resulting C<Module::Build> object to the caller. Any key-value
767 arguments given to C<new_from_context()> are essentially like
768 command line arguments given to the F<Build.PL> script, so for example
769 you could pass C<< verbose => 1 >> to this method to turn on
776 You'll probably never call this method directly, it's only called from
777 the auto-generated C<Build> script. The C<new()> method is only
778 called once, when the user runs C<perl Build.PL>. Thereafter, when
779 the user runs C<Build test> or another action, the C<Module::Build>
780 object is created using the C<resume()> method to re-instantiate with
781 the settings given earlier to C<new()>.
787 This creates a new C<Module::Build> subclass on the fly, as described
788 in the L<Module::Build::Authoring/"SUBCLASSING"> section. The caller
789 must provide either a C<class> or C<code> parameter, or both. The
790 C<class> parameter indicates the name to use for the new subclass, and
791 defaults to C<MyModuleBuilder>. The C<code> parameter specifies Perl
792 code to use as the body of the subclass.
801 =item add_build_element($type)
805 Adds a new type of entry to the build process. Accepts a single
806 string specifying its type-name. There must also be a method defined
807 to process things of that type, e.g. if you add a build element called
808 C<'foo'>, then you must also define a method called
809 C<process_foo_files()>.
812 L<Module::Build::Cookbook/"Adding new file types to the build process">.
814 =item add_to_cleanup(@files)
818 You may call C<< $self->add_to_cleanup(@patterns) >> to tell
819 C<Module::Build> that certain files should be removed when the user
820 performs the C<Build clean> action. The arguments to the method are
821 patterns suitable for passing to Perl's C<glob()> function, specified
822 in either Unix format or the current machine's native format. It's
823 usually convenient to use Unix format when you hard-code the filenames
824 (e.g. in F<Build.PL>) and the native format when the names are
825 programmatically generated (e.g. in a testing script).
827 I decided to provide a dynamic method of the C<$build> object, rather
828 than just use a static list of files named in the F<Build.PL>, because
829 these static lists can get difficult to manage. I usually prefer to
830 keep the responsibility for registering temporary files close to the
831 code that creates them.
837 my $args_href = $build->args;
838 my %args = $build->args;
839 my $arg_value = $build->args($key);
840 $build->args($key, $value);
842 This method is the preferred interface for retrieving the arguments passed via
843 command line options to F<Build.PL> or F<Build>, minus the Module-Build
846 When called in in a scalar context with no arguments, this method returns a
847 reference to the hash storing all of the arguments; in an array context, it
848 returns the hash itself. When passed a single argument, it returns the value
849 stored in the args hash for that option key. When called with two arguments,
850 the second argument is assigned to the args hash under the key passed as the
853 =item autosplit_file($from, $to)
857 Invokes the L<AutoSplit> module on the C<$from> file, sending the
858 output to the C<lib/auto> directory inside C<$to>. C<$to> is
859 typically the C<blib/> directory.
865 Returns a string containing the root-level directory of this build,
866 i.e. where the C<Build.PL> script and the C<lib> directory can be
867 found. This is usually the same as the current working directory,
868 because the C<Build> script will C<chdir()> into this directory as
869 soon as it begins execution.
871 =item build_requires()
875 Returns a hash reference indicating the C<build_requires>
876 prerequisites that were passed to the C<new()> method.
882 Returns the internal ExtUtils::CBuilder object that can be used for
883 compiling & linking C code. If no such object is available (e.g. if
884 the system has no compiler installed) an exception will be thrown.
887 =item check_installed_status($module, $version)
891 This method returns a hash reference indicating whether a version
892 dependency on a certain module is satisfied. The C<$module> argument
893 is given as a string like C<"Data::Dumper"> or C<"perl">, and the
894 C<$version> argument can take any of the forms described in L</requires>
895 above. This allows very fine-grained version checking.
897 The returned hash reference has the following structure:
900 ok => $whether_the_dependency_is_satisfied,
901 have => $version_already_installed,
902 need => $version_requested, # Same as incoming $version argument
903 message => $informative_error_message,
906 If no version of C<$module> is currently installed, the C<have> value
907 will be the string C<< "<none>" >>. Otherwise the C<have> value will
908 simply be the version of the installed module. Note that this means
909 that if C<$module> is installed but doesn't define a version number,
910 the C<have> value will be C<undef> - this is why we don't use C<undef>
911 for the case when C<$module> isn't installed at all.
913 This method may be called either as an object method
914 (C<< $build->check_installed_status($module, $version) >>)
916 (C<< Module::Build->check_installed_status($module, $version) >>).
918 =item check_installed_version($module, $version)
922 Like L<check_installed_status()|/"check_installed_status($module, $version)">,
923 but simply returns true or false depending on whether module
924 C<$module> satisfies the dependency C<$version>.
926 If the check succeeds, the return value is the actual version of
927 C<$module> installed on the system. This allows you to do the
930 my $installed = $build->check_installed_version('DBI', '1.15');
932 print "Congratulations, version $installed of DBI is installed.\n";
934 die "Sorry, you must install DBI.\n";
937 If the check fails, we return false and set C<$@> to an informative
940 If C<$version> is any non-true value (notably zero) and any version of
941 C<$module> is installed, we return true. In this case, if C<$module>
942 doesn't define a version, or if its version is zero, we return the
943 special value "0 but true", which is numerically zero, but logically
946 In general you might prefer to use C<check_installed_status> if you
947 need detailed information, or this method if you just need a yes/no
950 =item compare_versions($v1, $op, $v2)
954 Compares two module versions C<$v1> and C<$v2> using the operator
955 C<$op>, which should be one of Perl's numeric operators like C<!=> or
956 C<< >= >> or the like. We do at least a halfway-decent job of
957 handling versions that aren't strictly numeric, like C<0.27_02>, but
958 exotic stuff will likely cause problems.
960 In the future, the guts of this method might be replaced with a call
961 out to C<version.pm>.
965 =item config($key, $value)
967 =item config() [deprecated]
971 With a single argument C<$key>, returns the value associated with that
972 key in the C<Config.pm> hash, including any changes the author or user
975 With C<$key> and C<$value> arguments, sets the value for future
976 callers of C<config($key)>.
978 With no arguments, returns a hash reference containing all such
979 key-value pairs. This usage is deprecated, though, because it's a
980 resource hog and violates encapsulation.
982 =item config_data($name)
984 =item config_data($name => $value)
988 With a single argument, returns the value of the configuration
989 variable C<$name>. With two arguments, sets the given configuration
990 variable to the given value. The value may be any Perl scalar that's
991 serializable with C<Data::Dumper>. For instance, if you write a
992 module that can use a MySQL or PostgreSQL back-end, you might create
993 configuration variables called C<mysql_connect> and
994 C<postgres_connect>, and set each to an array of connection parameters
995 for C<< DBI->connect() >>.
997 Configuration values set in this way using the Module::Build object
998 will be available for querying during the build/test process and after
999 installation via the generated C<...::ConfigData> module, as
1000 C<< ...::ConfigData->config($name) >>.
1002 The L<feature()|/"feature($name)"> and C<config_data()> methods represent
1003 Module::Build's main support for configuration of installed modules.
1004 See also L<Module::Build::Authoring/"SAVING CONFIGURATION INFORMATION">.
1010 Returns a hash reference indicating the C<conflicts> prerequisites
1011 that were passed to the C<new()> method.
1013 =item contains_pod($file)
1017 [Deprecated] Please see L<Module::Build::ModuleInfo> instead.
1019 Returns true if the given file appears to contain POD documentation.
1020 Currently this checks whether the file has a line beginning with
1021 '=pod', '=head', or '=item', but the exact semantics may change in the
1024 =item copy_if_modified(%parameters)
1028 Takes the file in the C<from> parameter and copies it to the file in
1029 the C<to> parameter, or the directory in the C<to_dir> parameter, if
1030 the file has changed since it was last copied (or if it doesn't exist
1031 in the new location). By default the entire directory structure of
1032 C<from> will be copied into C<to_dir>; an optional C<flatten>
1033 parameter will copy into C<to_dir> without doing so.
1035 Returns the path to the destination file, or C<undef> if nothing
1036 needed to be copied.
1038 Any directories that need to be created in order to perform the
1039 copying will be automatically created.
1041 The destination file is set to read-only. If the source file has the
1042 executable bit set, then the destination file will be made executable.
1044 =item create_build_script()
1048 Creates an executable script called C<Build> in the current directory
1049 that will be used to execute further user actions. This script is
1050 roughly analogous (in function, not in form) to the Makefile created
1051 by C<ExtUtils::MakeMaker>. This method also creates some temporary
1052 data in a directory called C<_build/>. Both of these will be removed
1053 when the C<realclean> action is performed.
1055 Among the files created in C<_build/> is a F<_build/prereqs> file
1056 containing the set of prerequisites for this distribution, as a hash
1057 of hashes. This file may be C<eval()>-ed to obtain the authoritative
1058 set of prereqs, which might be different from the contents of
1059 F<META.yml> (because F<Build.PL> might have set them dynamically).
1060 But fancy developers take heed: do not put any fancy custom runtime
1061 code in the F<_build/prereqs> file, leave it as a static declaration
1062 containing only strings and numbers. Similarly, do not alter the
1063 structure of the internal C<< $self->{properties}{requires} >> (etc.)
1064 data members, because that's where this data comes from.
1066 =item current_action()
1070 Returns the name of the currently-running action, such as "build" or
1071 "test". This action is not necessarily the action that was originally
1072 invoked by the user. For example, if the user invoked the "test"
1073 action, current_action() would initially return "test". However,
1074 action "test" depends on action "code", so current_action() will
1075 return "code" while that dependency is being executed. Once that
1076 action has completed, current_action() will again return "test".
1078 If you need to know the name of the original action invoked by the
1079 user, see L</invoked_action()> below.
1081 =item depends_on(@actions)
1085 Invokes the named action or list of actions in sequence. Using this
1086 method is preferred to calling the action explicitly because it
1087 performs some internal record-keeping, and it ensures that the same
1088 action is not invoked multiple times (note: in future versions of
1089 Module::Build it's conceivable that this run-only-once mechanism will
1090 be changed to something more intelligent).
1092 Note that the name of this method is something of a misnomer; it
1093 should really be called something like
1094 C<invoke_actions_unless_already_invoked()> or something, but for
1095 better or worse (perhaps better!) we were still thinking in
1096 C<make>-like dependency terms when we created this method.
1098 See also L<dispatch()|/"dispatch($action, %args)">. The main
1099 distinction between the two is that C<depends_on()> is meant to call
1100 an action from inside another action, whereas C<dispatch()> is meant
1101 to set the very top action in motion.
1103 =item dir_contains($first_dir, $second_dir)
1107 Returns true if the first directory logically contains the second
1108 directory. This is just a convenience function because C<File::Spec>
1109 doesn't really provide an easy way to figure this out (but
1110 C<Path::Class> does...).
1112 =item dispatch($action, %args)
1116 Invokes the build action C<$action>. Optionally, a list of options
1117 and their values can be passed in. This is equivalent to invoking an
1118 action at the command line, passing in a list of options.
1120 Custom options that have not been registered must be passed in as a
1121 hash reference in a key named "args":
1123 $build->dispatch('foo', verbose => 1, args => { my_option => 'value' });
1125 This method is intended to be used to programmatically invoke build
1126 actions, e.g. by applications controlling Module::Build-based builds
1127 rather than by subclasses.
1129 See also L<depends_on()|/"depends_on(@actions)">. The main
1130 distinction between the two is that C<depends_on()> is meant to call
1131 an action from inside another action, whereas C<dispatch()> is meant
1132 to set the very top action in motion.
1138 Returns the name of the directory that will be created during the
1139 C<dist> action. The name is derived from the C<dist_name> and
1140 C<dist_version> properties.
1146 Returns the name of the current distribution, as passed to the
1147 C<new()> method in a C<dist_name> or modified C<module_name>
1150 =item dist_version()
1154 Returns the version of the current distribution, as determined by the
1155 C<new()> method from a C<dist_version>, C<dist_version_from>, or
1156 C<module_name> parameter.
1158 =item do_system($cmd, @args)
1162 This is a fairly simple wrapper around Perl's C<system()> built-in
1163 command. Given a command and an array of optional arguments, this
1164 method will print the command to C<STDOUT>, and then execute it using
1165 Perl's C<system()>. It returns true or false to indicate success or
1166 failure (the opposite of how C<system()> works, but more intuitive).
1168 Note that if you supply a single argument to C<do_system()>, it
1169 will/may be processed by the systems's shell, and any special
1170 characters will do their special things. If you supply multiple
1171 arguments, no shell will get involved and the command will be executed
1174 =item feature($name)
1176 =item feature($name => $value)
1180 With a single argument, returns true if the given feature is set.
1181 With two arguments, sets the given feature to the given boolean value.
1182 In this context, a "feature" is any optional functionality of an
1183 installed module. For instance, if you write a module that could
1184 optionally support a MySQL or PostgreSQL backend, you might create
1185 features called C<mysql_support> and C<postgres_support>, and set them
1186 to true/false depending on whether the user has the proper databases
1187 installed and configured.
1189 Features set in this way using the Module::Build object will be
1190 available for querying during the build/test process and after
1191 installation via the generated C<...::ConfigData> module, as
1192 C<< ...::ConfigData->feature($name) >>.
1194 The C<feature()> and C<config_data()> methods represent
1195 Module::Build's main support for configuration of installed modules.
1196 See also L<Module::Build::Authoring/"SAVING CONFIGURATION INFORMATION">.
1198 =item fix_shebang_line(@files)
1202 Modify any "shebang" line in the specified files to use the path to the
1203 perl executable being used for the current build. Files are modified
1204 in-place. The existing shebang line must have a command that contains
1205 "C<perl>"; arguments to the command do not count. In particular, this
1206 means that the use of C<#!/usr/bin/env perl> will not be changed.
1208 For an explanation of shebang lines, see
1209 L<http://en.wikipedia.org/wiki/Shebang_%28Unix%29>.
1211 =item have_c_compiler()
1215 Returns true if the current system seems to have a working C compiler.
1216 We currently determine this by attempting to compile a simple C source
1217 file and reporting whether the attempt was successful.
1219 =item install_base_relpaths()
1221 =item install_base_relpaths($type)
1223 =item install_base_relpaths($type => $path)
1227 Set or retrieve the relative paths that are appended to
1228 C<install_base> for any installable element. This is useful if you
1229 want to set the relative install path for custom build elements.
1231 With no argument, it returns a reference to a hash containing all
1232 elements and their respective values. This hash should not be modified
1233 directly; use the multi-argument below form to change values.
1235 The single argument form returns the value associated with the
1238 The multi-argument form allows you to set the paths for element types.
1239 C<$value> must be a relative path using unix-like paths. (A series of
1240 directories seperated by slashes. Eg 'foo/bar'.) The return value is a
1241 localized path based on C<$value>.
1243 Assigning the value C<undef> to an element causes it to be removed.
1245 =item install_destination($type)
1249 Returns the directory in which items of type C<$type> (e.g. C<lib>,
1250 C<arch>, C<bin>, or anything else returned by the L</install_types()>
1251 method) will be installed during the C<install> action. Any settings
1252 for C<install_path>, C<install_base>, and C<prefix> are taken into
1253 account when determining the return value.
1255 =item install_path()
1257 =item install_path($type)
1259 =item install_path($type => $path)
1263 Set or retrieve paths for specific installable elements. This is
1264 useful when you want to examine any explicit install paths specified
1265 by the user on the command line, or if you want to set the install
1266 path for a specific installable element based on another attribute
1267 like C<install_base()>.
1269 With no argument, it returns a reference to a hash containing all
1270 elements and their respective values. This hash should not be modified
1271 directly; use the multi-argument below form to change values.
1273 The single argument form returns the value associated with the
1276 The multi-argument form allows you to set the paths for element types.
1277 The supplied C<$path> should be an absolute path to install elements
1278 of C<$type>. The return value is C<$path>.
1280 Assigning the value C<undef> to an element causes it to be removed.
1282 =item install_types()
1286 Returns a list of installable types that this build knows about.
1287 These types each correspond to the name of a directory in F<blib/>,
1288 and the list usually includes items such as C<lib>, C<arch>, C<bin>,
1289 C<script>, C<libdoc>, C<bindoc>, and if HTML documentation is to be
1290 built, C<libhtml> and C<binhtml>. Other user-defined types may also
1293 =item invoked_action()
1297 This is the name of the original action invoked by the user. This
1298 value is set when the user invokes F<Build.PL>, the F<Build> script,
1299 or programatically through the L<dispatch()|/"dispatch($action, %args)">
1300 method. It does not change as sub-actions are executed as
1301 dependencies are evaluated.
1303 To get the name of the currently executing dependency, see
1304 L</current_action()> above.
1310 =item notes($key => $value)
1314 The C<notes()> value allows you to store your own persistent
1315 information about the build, and to share that information among
1316 different entities involved in the build. See the example in the
1317 C<current()> method.
1319 The C<notes()> method is essentally a glorified hash access. With no
1320 arguments, C<notes()> returns the entire hash of notes. With one argument,
1321 C<notes($key)> returns the value associated with the given key. With two
1322 arguments, C<notes($key, $value)> sets the value associated with the given key
1323 to C<$value> and returns the new value.
1325 The lifetime of the C<notes> data is for "a build" - that is, the
1326 C<notes> hash is created when C<perl Build.PL> is run (or when the
1327 C<new()> method is run, if the Module::Build Perl API is being used
1328 instead of called from a shell), and lasts until C<perl Build.PL> is
1329 run again or the C<clean> action is run.
1335 Returns a string containing the working directory that was in effect
1336 before the F<Build> script chdir()-ed into the C<base_dir>. This
1337 might be useful for writing wrapper tools that might need to chdir()
1344 If you're subclassing Module::Build and some code needs to alter its
1345 behavior based on the current platform, you may only need to know
1346 whether you're running on Windows, Unix, MacOS, VMS, etc., and not the
1347 fine-grained value of Perl's C<$^O> variable. The C<os_type()> method
1348 will return a string like C<Windows>, C<Unix>, C<MacOS>, C<VMS>, or
1349 whatever is appropriate. If you're running on an unknown platform, it
1350 will return C<undef> - there shouldn't be many unknown platforms
1355 =item is_windowsish()
1359 Convenience functions that return a boolean value indicating whether
1360 this platform behaves respectively like VMS, Windows, or Unix. For
1361 arbitrary reasons other platforms don't get their own such functions,
1365 =item prefix_relpaths()
1367 =item prefix_relpaths($installdirs)
1369 =item prefix_relpaths($installdirs, $type)
1371 =item prefix_relpaths($installdirs, $type => $path)
1375 Set or retrieve the relative paths that are appended to C<prefix> for
1376 any installable element. This is useful if you want to set the
1377 relative install path for custom build elements.
1379 With no argument, it returns a reference to a hash containing all
1380 elements and their respective values as defined by the current
1381 C<installdirs> setting.
1383 With a single argument, it returns a reference to a hash containing
1384 all elements and their respective values as defined by
1387 The hash returned by the above calls should not be modified directly;
1388 use the three-argument below form to change values.
1390 The two argument form returns the value associated with the
1393 The multi-argument form allows you to set the paths for element types.
1394 C<$value> must be a relative path using unix-like paths. (A series of
1395 directories seperated by slashes. Eg 'foo/bar'.) The return value is a
1396 localized path based on C<$value>.
1398 Assigning the value C<undef> to an element causes it to be removed.
1400 =item prepare_metadata()
1404 This method is provided for authors to override to customize the
1405 fields of F<META.yml>. It is passed a YAML::Node node object which can
1406 be modified as desired and then returned. E.g.
1408 package My::Builder;
1409 use base 'Module::Build';
1411 sub prepare_metadata {
1413 my $node = $self->SUPER::prepare_metadata( shift );
1414 $node->{custom_field} = 'foo';
1418 =item prereq_failures()
1422 Returns a data structure containing information about any failed
1423 prerequisites (of any of the types described above), or C<undef> if
1424 all prerequisites are met.
1426 The data structure returned is a hash reference. The top level keys
1427 are the type of prerequisite failed, one of "requires",
1428 "build_requires", "conflicts", or "recommends". The associated values
1429 are hash references whose keys are the names of required (or
1430 conflicting) modules. The associated values of those are hash
1431 references indicating some information about the failure. For example:
1436 message => 'Version 0.42 is installed, but we need version 0.59',
1444 message => 'Prerequisite Foo isn't installed',
1447 This hash has the same structure as the hash returned by the
1448 C<check_installed_status()> method, except that in the case of
1449 "conflicts" dependencies we change the "need" key to "conflicts" and
1450 construct a proper message.
1454 # Check a required dependency on Foo::Bar
1455 if ( $build->prereq_failures->{requires}{Foo::Bar} ) { ...
1457 # Check whether there were any failures
1458 if ( $build->prereq_failures ) { ...
1460 # Show messages for all failures
1461 my $failures = $build->prereq_failures;
1462 while (my ($type, $list) = each %$failures) {
1463 while (my ($name, $hash) = each %$list) {
1464 print "Failure for $name: $hash->{message}\n";
1468 =item prereq_report()
1472 Returns a human-readable (table-form) string showing all
1473 prerequisites, the versions required, and the versions actually
1474 installed. This can be useful for reviewing the configuration of your
1475 system prior to a build, or when compiling data to send for a bug
1476 report. The C<prereq_report> action is just a thin wrapper around the
1477 C<prereq_report()> method.
1479 =item prompt($message, $default)
1483 Asks the user a question and returns their response as a string. The
1484 first argument specifies the message to display to the user (for
1485 example, C<"Where do you keep your money?">). The second argument,
1486 which is optional, specifies a default answer (for example,
1487 C<"wallet">). The user will be asked the question once.
1489 If C<prompt()> detects that it is not running interactively and there
1490 is nothing on STDIN or if the PERL_MM_USE_DEFAULT environment variable
1491 is set to true, the $default will be used without prompting.
1493 To prevent automated processes from blocking, the user must either set
1494 PERL_MM_USE_DEFAULT or attach something to STDIN (this can be a
1495 pipe/file containing a scripted set of answers or /dev/null.)
1497 If no $default is provided an empty string will be used instead. In
1498 non-interactive mode, the absence of $default is an error (though
1499 explicitly passing C<undef()> as the default is valid as of 0.27.)
1501 This method may be called as a class or object method.
1507 Returns a hash reference indicating the C<recommends> prerequisites
1508 that were passed to the C<new()> method.
1514 Returns a hash reference indicating the C<requires> prerequisites that
1515 were passed to the C<new()> method.
1517 =item rscan_dir($dir, $pattern)
1521 Uses C<File::Find> to traverse the directory C<$dir>, returning a
1522 reference to an array of entries matching C<$pattern>. C<$pattern>
1523 may either be a regular expression (using C<qr//> or just a plain
1524 string), or a reference to a subroutine that will return true for
1525 wanted entries. If C<$pattern> is not given, all entries will be
1530 # All the *.pm files in lib/
1531 $m->rscan_dir('lib', qr/\.pm$/)
1533 # All the files in blib/ that aren't *.html files
1534 $m->rscan_dir('blib', sub {-f $_ and not /\.html$/});
1536 # All the files in t/
1539 =item runtime_params()
1541 =item runtime_params($key)
1545 The C<runtime_params()> method stores the values passed on the command line
1546 for valid properties (that is, any command line options for which
1547 C<valid_property()> returns a true value). The value on the command line may
1548 override the default value for a property, as well as any value specified in a
1549 call to C<new()>. This allows you to programmatically tell if C<perl Build.PL>
1550 or any execution of C<./Build> had command line options specified that
1551 override valid properties.
1553 The C<runtime_params()> method is essentally a glorified read-only hash. With
1554 no arguments, C<runtime_params()> returns the entire hash of properties
1555 specified on the command line. With one argument, C<runtime_params($key)>
1556 returns the value associated with the given key.
1558 The lifetime of the C<runtime_params> data is for "a build" - that is, the
1559 C<runtime_params> hash is created when C<perl Build.PL> is run (or when the
1560 C<new()> method is called, if the Module::Build Perl API is being used instead
1561 of called from a shell), and lasts until C<perl Build.PL> is run again or the
1562 C<clean> action is run.
1564 =item script_files()
1568 Returns a hash reference whose keys are the perl script files to be
1569 installed, if any. This corresponds to the C<script_files> parameter to the
1570 C<new()> method. With an optional argument, this parameter may be set
1573 For backward compatibility, the C<scripts()> method does exactly the
1574 same thing as C<script_files()>. C<scripts()> is deprecated, but it
1575 will stay around for several versions to give people time to
1578 =item up_to_date($source_file, $derived_file)
1580 =item up_to_date(\@source_files, \@derived_files)
1584 This method can be used to compare a set of source files to a set of
1585 derived files. If any of the source files are newer than any of the
1586 derived files, it returns false. Additionally, if any of the derived
1587 files do not exist, it returns false. Otherwise it returns true.
1589 The arguments may be either a scalar or an array reference of file
1592 =item y_n($message, $default)
1596 Asks the user a yes/no question using C<prompt()> and returns true or
1597 false accordingly. The user will be asked the question repeatedly
1598 until they give an answer that looks like "yes" or "no".
1600 The first argument specifies the message to display to the user (for
1601 example, C<"Shall I invest your money for you?">), and the second
1602 argument specifies the default answer (for example, C<"y">).
1604 Note that the default is specified as a string like C<"y"> or C<"n">,
1605 and the return value is a Perl boolean value like 1 or 0. I thought
1606 about this for a while and this seemed like the most useful way to do
1609 This method may be called as a class or object method.
1614 =head2 Autogenerated Accessors
1616 In addition to the aforementioned methods, there are also some get/set
1617 accessor methods for the following properties:
1623 =item allow_mb_mismatch()
1637 =item build_elements()
1639 =item build_requires()
1641 =item build_script()
1647 =item configure_requires()
1651 =item create_makefile_pl()
1653 =item create_packlist()
1655 =item create_readme()
1665 =item include_dirs()
1667 =item install_base()
1669 =item install_sets()
1677 =item magic_number()
1691 =item original_prefix()
1703 =item prereq_action_types()
1705 =item program_name()
1711 =item recurse_into()
1713 =item recursive_test_files()
1721 =item tap_harness_args()
1723 =item test_file_exts()
1727 =item use_tap_harness()
1736 =head1 MODULE METADATA
1738 If you would like to add other useful metadata, C<Module::Build>
1739 supports this with the C<meta_add> and C<meta_merge> arguments to
1740 L</new>. The authoritative list of supported metadata can be found at
1741 L<http://module-build.sourceforge.net/META-spec-current.html>, but for
1742 convenience - here are a few of the more useful ones:
1748 For describing the distribution using keyword (or "tags") in order to
1749 make CPAN.org indexing and search more efficient and useful.
1751 See L<http://module-build.sourceforge.net/META-spec-current.html#keywords>.
1755 A list of additional resources available for users of the
1756 distribution. This can include links to a homepage on the web, a
1757 bugtracker, the repository location, a even subscription page for the
1758 distribution mailing list.
1760 See L<http://module-build.sourceforge.net/META-spec-current.html#resources>.
1767 Ken Williams <kwilliams@cpan.org>
1772 Copyright (c) 2001-2006 Ken Williams. All rights reserved.
1774 This library is free software; you can redistribute it and/or
1775 modify it under the same terms as Perl itself.
1780 perl(1), L<Module::Build>(3), L<Module::Build::Authoring>(3),
1781 L<Module::Build::Cookbook>(3), L<ExtUtils::MakeMaker>(3), L<YAML>(3)
1783 F<META.yml> Specification:
1784 L<http://module-build.sourceforge.net/META-spec-current.html>