api.pod

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behavior based on the current platform, you may only need to know
whether you're running on Windows, Unix, MacOS, VMS, etc., and not the
fine-grained value of Perl's C<$^O> variable.  The C<os_type()> method
will return a string like C<Windows>, C<Unix>, C<MacOS>, C<VMS>, or
whatever is appropriate.  If you're running on an unknown platform, it
will return C<undef> - there shouldn't be many unknown platforms
though.

=item is_vmsish()

=item is_windowsish()

=item is_unixish()

Convenience functions that return a boolean value indicating whether
this platform behaves respectively like VMS, Windows, or Unix.  For
arbitrary reasons other platforms don't get their own such functions,
at least not yet.


=item prefix_relpaths()

=item prefix_relpaths($installdirs)

=item prefix_relpaths($installdirs, $type)

=item prefix_relpaths($installdirs, $type => $path)

[version 0.28]

Set or retrieve the relative paths that are appended to C<prefix> for
any installable element.  This is useful if you want to set the
relative install path for custom build elements.

With no argument, it returns a reference to a hash containing all
elements and their respective values as defined by the current
C<installdirs> setting.

With a single argument, it returns a reference to a hash containing
all elements and their respective values as defined by
C<$installdirs>.

The hash returned by the above calls should not be modified directly;
use the three-argument below form to change values.

The two argument form returns the value associated with the
element C<$type>.

The multi-argument form allows you to set the paths for element types.
C<$value> must be a relative path using unix-like paths.  (A series of
directories seperated by slashes.  Eg 'foo/bar'.)  The return value is a
localized path based on C<$value>.

Assigning the value C<undef> to an element causes it to be removed.

=item prepare_metadata()

[version 0.28]

This method is provided for authors to override to customize the
fields of F<META.yml>.  It is passed a YAML::Node node object which can
be modified as desired and then returned.  E.g.

  package My::Builder;
  use base 'Module::Build';

  sub prepare_metadata {
    my $self = shift;
    my $node = $self->SUPER::prepare_metadata( shift );
    $node->{custom_field} = 'foo';
    return $node;
  }

=item prereq_failures()

[version 0.11]

Returns a data structure containing information about any failed
prerequisites (of any of the types described above), or C<undef> if
all prerequisites are met.

The data structure returned is a hash reference.  The top level keys
are the type of prerequisite failed, one of "requires",
"build_requires", "conflicts", or "recommends".  The associated values
are hash references whose keys are the names of required (or
conflicting) modules.  The associated values of those are hash
references indicating some information about the failure.  For example:

  {
   have => '0.42',
   need => '0.59',
   message => 'Version 0.42 is installed, but we need version 0.59',
  }

or

  {
   have => '<none>',
   need => '0.59',
   message => 'Prerequisite Foo isn't installed',
  }

This hash has the same structure as the hash returned by the
C<check_installed_status()> method, except that in the case of
"conflicts" dependencies we change the "need" key to "conflicts" and
construct a proper message.

Examples:

  # Check a required dependency on Foo::Bar
  if ( $build->prereq_failures->{requires}{Foo::Bar} ) { ...

  # Check whether there were any failures
  if ( $build->prereq_failures ) { ...

  # Show messages for all failures
  my $failures = $build->prereq_failures;
  while (my ($type, $list) = each %$failures) {
    while (my ($name, $hash) = each %$list) {
      print "Failure for $name: $hash->{message}\n";
    }
  }

=item prereq_report()

[version 0.28]

Returns a human-readable (table-form) string showing all
prerequisites, the versions required, and the versions actually
installed.  This can be useful for reviewing the configuration of your
system prior to a build, or when compiling data to send for a bug
report.  The C<prereq_report> action is just a thin wrapper around the
C<prereq_report()> method.

=item prompt($message, $default)

[version 0.12]

Asks the user a question and returns their response as a string.  The
first argument specifies the message to display to the user (for
example, C<"Where do you keep your money?">).  The second argument,
which is optional, specifies a default answer (for example,
C<"wallet">).  The user will be asked the question once.

If C<prompt()> detects that it is not running interactively and there
is nothing on STDIN or if the PERL_MM_USE_DEFAULT environment variable
is set to true, the $default will be used without prompting.

To prevent automated processes from blocking, the user must either set
PERL_MM_USE_DEFAULT or attach something to STDIN (this can be a
pipe/file containing a scripted set of answers or /dev/null.)

If no $default is provided an empty string will be used instead.  In
non-interactive mode, the absence of $default is an error (though
explicitly passing C<undef()> as the default is valid as of 0.27.)

This method may be called as a class or object method.

=item recommends()

[version 0.21]

Returns a hash reference indicating the C<recommends> prerequisites
that were passed to the C<new()> method.

=item requires()

[version 0.21]

Returns a hash reference indicating the C<requires> prerequisites that
were passed to the C<new()> method.

=item rscan_dir($dir, $pattern)

[version 0.28]

Uses C<File::Find> to traverse the directory C<$dir>, returning a
reference to an array of entries matching C<$pattern>.  C<$pattern>
may either be a regular expression (using C<qr//> or just a plain
string), or a reference to a subroutine that will return true for
wanted entries.  If C<$pattern> is not given, all entries will be
returned.

Examples:

 # All the *.pm files in lib/
 $m->rscan_dir('lib', qr/\.pm$/)

 # All the files in blib/ that aren't *.html files
 $m->rscan_dir('blib', sub {-f $_ and not /\.html$/});

 # All the files in t/
 $m->rscan_dir('t');

=item runtime_params()

=item runtime_params($key)

[version 0.28]

The C<runtime_params()> method stores the values passed on the command line
for valid properties (that is, any command line options for which
C<valid_property()> returns a true value).  The value on the command line may
override the default value for a property, as well as any value specified in a
call to C<new()>.  This allows you to programmatically tell if C<perl Build.PL>
or any execution of C<./Build> had command line options specified that
override valid properties.

The C<runtime_params()> method is essentally a glorified read-only hash.  With
no arguments, C<runtime_params()> returns the entire hash of properties
specified on the command line.  With one argument, C<runtime_params($key)>
returns the value associated with the given key.

The lifetime of the C<runtime_params> data is for "a build" - that is, the
C<runtime_params> hash is created when C<perl Build.PL> is run (or when the
C<new()> method is called, if the Module::Build Perl API is being used instead
of called from a shell), and lasts until C<perl Build.PL> is run again or the
C<clean> action is run.

=item script_files()

[version 0.18]

Returns a hash reference whose keys are the perl script files to be
installed, if any.  This corresponds to the C<script_files> parameter to the
C<new()> method.  With an optional argument, this parameter may be set
dynamically.

For backward compatibility, the C<scripts()> method does exactly the
same thing as C<script_files()>.  C<scripts()> is deprecated, but it
will stay around for several versions to give people time to
transition.

=item up_to_date($source_file, $derived_file)

=item up_to_date(\@source_files, \@derived_files)

[version 0.20]

This method can be used to compare a set of source files to a set of
derived files.  If any of the source files are newer than any of the
derived files, it returns false.  Additionally, if any of the derived
files do not exist, it returns false.  Otherwise it returns true.

The arguments may be either a scalar or an array reference of file
names.

=item y_n($message, $default)

[version 0.12]

Asks the user a yes/no question using C<prompt()> and returns true or
false accordingly.  The user will be asked the question repeatedly
until they give an answer that looks like "yes" or "no".

The first argument specifies the message to display to the user (for
example, C<"Shall I invest your money for you?">), and the second
argument specifies the default answer (for example, C<"y">).

Note that the default is specified as a string like C<"y"> or C<"n">,
and the return value is a Perl boolean value like 1 or 0.  I thought
about this for a while and this seemed like the most useful way to do
it.

This method may be called as a class or object method.

=back


=head2 Autogenerated Accessors

In addition to the aforementioned methods, there are also some get/set
accessor methods for the following properties:

=over 4

=item PL_files()

=item allow_mb_mismatch()

=item autosplit()

=item base_dir()

=item bindoc_dirs()

=item blib()

=item build_bat()

=item build_class()

=item build_elements()

=item build_requires()

=item build_script()

=item c_source()

=item config_dir()

=item configure_requires()

=item conflicts()

=item create_makefile_pl()

=item create_packlist()

=item create_readme()

=item debugger()

=item destdir()

=item get_options()

=item html_css()

=item include_dirs()

=item install_base()

=item install_sets()

=item installdirs()

=item libdoc_dirs()

=item license()

=item magic_number()

=item mb_version()

=item meta_add()

=item meta_merge()

=item metafile()

=item module_name()

=item orig_dir()

=item original_prefix()

=item perl()

=item pm_files()

=item pod_files()

=item pollute()

=item prefix()

=item prereq_action_types()

=item quiet()

=item recommends()

=item recurse_into()

=item recursive_test_files()

=item requires()

=item scripts()

=item use_rcfile()

=item verbose()

=item xs_files()

=back


=head1 MODULE METADATA

If you would like to add other useful metadata, C<Module::Build>
supports this with the C<meta_add> and C<meta_merge> arguments to
L</new>. The authoritative list of supported metadata can be found at
L<http://module-build.sourceforge.net/META-spec-current.html>, but for
convenience - here are a few of the more useful ones:

=over 4

=item keywords

For describing the distribution using keyword (or "tags") in order to
make CPAN.org indexing and search more efficient and useful.

See L<http://module-build.sourceforge.net/META-spec-current.html#keywords>.

=item resources

A list of additional resources available for users of the
distribution. This can include links to a homepage on the web, a
bugtracker, the repository location, a even subscription page for the
distribution mailing list.

See L<http://module-build.sourceforge.net/META-spec-current.html#resources>.

=back


=head1 AUTHOR

Ken Williams <[e-mail]>


=head1 COPYRIGHT

Copyright (c) 2001-2006 Ken Williams.  All rights reserved.

This library is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.


=head1 SEE ALSO

perl(1), L<Module::Build>(3), L<Module::Build::Authoring>(3),
L<Module::Build::Cookbook>(3), L<ExtUtils::MakeMaker>(3), L<YAML>(3)

F<META.yml> Specification:
L<http://module-build.sourceforge.net/META-spec-current.html>

=cut