Module::Build::AuthoriUser)Contributed Perl DocumenModule::Build::Authoring(3)
NAME
Module::Build::Authoring - Authoring Module::Build modules
DESCRIPTION
When creating a "Build.PL" script for a module, something like the
following code will typically be used:
use Module::Build;
my $build = Module::Build->new
(
module_name => 'Foo::Bar',
license => 'perl',
requires => {
'perl' => '5.6.1',
'Some::Module' => '1.23',
'Other::Module' => '>= 1.2, != 1.5, < 2.0',
},
);
$build->create_build_script;
A simple module could get away with something as short as this for its
"Build.PL" script:
use Module::Build;
Module::Build->new(
module_name => 'Foo::Bar',
license => 'perl',
)->create_build_script;
The model used by "Module::Build" is a lot like the "MakeMaker"
metaphor, with the following correspondences:
In Module::Build In ExtUtils::MakeMaker
--------------------------- ------------------------
Build.PL (initial script) Makefile.PL (initial script)
Build (a short perl script) Makefile (a long Makefile)
_build/ (saved state info) various config text in the Makefile
Any customization can be done simply by subclassing "Module::Build" and
adding a method called (for example) "ACTION_test", overriding the
default 'test' action. You could also add a method called
"ACTION_whatever", and then you could perform the action "Build
whatever".
For information on providing compatibility with "ExtUtils::MakeMaker",
see Module::Build::Compat and
<http://www.makemaker.org/wiki/index.cgi?ModuleBuildConversionGuide>;.
STRUCTURE
Module::Build creates a class hierarchy conducive to customization.
Here is the parent-child class hierarchy in classy ASCII art:
/--------------------\
| Your::Parent | (If you subclass Module::Build)
\--------------------/
|
|
/--------------------\ (Doesn't define any functionality
| Module::Build | of its own - just figures out what
\--------------------/ other modules to load.)
|
|
/-----------------------------------\ (Some values of $^O may
| Module::Build::Platform::$^O | define specialized functionality.
\-----------------------------------/ Otherwise it's ...::Default, a
| pass-through class.)
|
/--------------------------\
| Module::Build::Base | (Most of the functionality of
\--------------------------/ Module::Build is defined here.)
SUBCLASSING
Right now, there are two ways to subclass Module::Build. The first way
is to create a regular module (in a ".pm" file) that inherits from
Module::Build, and use that module's class instead of using
Module::Build directly:
------ in Build.PL: ----------
#!/usr/bin/perl
use lib q(/nonstandard/library/path);
use My::Builder; # Or whatever you want to call it
my $build = My::Builder->new
(
module_name => 'Foo::Bar', # All the regular args...
license => 'perl',
dist_author => 'A N Other <me AT here.au>',
requires => { Carp => 0 }
);
$build->create_build_script;
This is relatively straightforward, and is the best way to do things if
your My::Builder class contains lots of code. The
"create_build_script()" method will ensure that the current value of
@INC (including the "/nonstandard/library/path") is propagated to the
Build script, so that My::Builder can be found when running build
actions. If you find that you need to "chdir" into a different
directories in your subclass methods or actions, be sure to always
return to the original directory (available via the "base_dir()"
method) before returning control to the parent class. This is
important to avoid data serialization problems.
For very small additions, Module::Build provides a "subclass()" method
that lets you subclass Module::Build more conveniently, without
creating a separate file for your module:
------ in Build.PL: ----------
#!/usr/bin/perl
use Module::Build;
my $class = Module::Build->subclass
(
class => 'My::Builder',
code => q{
sub ACTION_foo {
print "I'm fooing to death!\n";
}
},
);
my $build = $class->new
(
module_name => 'Foo::Bar', # All the regular args...
license => 'perl',
dist_author => 'A N Other <me AT here.au>',
requires => { Carp => 0 }
);
$build->create_build_script;
Behind the scenes, this actually does create a ".pm" file, since the
code you provide must persist after Build.PL is run if it is to be very
useful.
See also the documentation for the "subclass()" in Module::Build::API
method.
PREREQUISITES
Types of prerequisites
To specify what versions of other modules are used by this
distribution, several types of prerequisites can be defined with the
following parameters:
configure_requires
Items that must be installed before configuring this distribution
(i.e. before running the Build.PL script). This might be a specific
minimum version of "Module::Build" or any other module the Build.PL
needs in order to do its stuff. Clients like "CPAN.pm" or
"CPANPLUS" will be expected to pick "configure_requires" out of the
META.yml file and install these items before running the "Build.PL".
If no configure_requires is specified, the current version of
Module::Build is automatically added to configure_requires.
build_requires
Items that are necessary for building and testing this distribution,
but aren't necessary after installation. This can help users who
only want to install these items temporarily. It also helps reduce
the size of the CPAN dependency graph if everything isn't smooshed
into "requires".
requires
Items that are necessary for basic functioning.
recommends
Items that are recommended for enhanced functionality, but there are
ways to use this distribution without having them installed. You
might also think of this as "can use" or "is aware of" or "changes
behavior in the presence of".
test_requires
Items that are necessary for testing.
conflicts
Items that can cause problems with this distribution when installed.
This is pretty rare.
Format of prerequisites
The prerequisites are given in a hash reference, where the keys are the
module names and the values are version specifiers:
requires => {
Foo::Module => '2.4',
Bar::Module => 0,
Ken::Module => '>= 1.2, != 1.5, < 2.0',
perl => '5.6.0'
},
The above four version specifiers have different effects. The value
'2.4' means that at least version 2.4 of "Foo::Module" must be
installed. The value 0 means that any version of "Bar::Module" is
acceptable, even if "Bar::Module" doesn't define a version. The more
verbose value '>= 1.2, != 1.5, < 2.0' means that "Ken::Module"'s
version must be at least 1.2, less than 2.0, and not equal to 1.5. The
list of criteria is separated by commas, and all criteria must be
satisfied.
A special "perl" entry lets you specify the versions of the Perl
interpreter that are supported by your module. The same version
dependency-checking semantics are available, except that we also
understand perl's new double-dotted version numbers.
XS Extensions
Modules which need to compile XS code should list "ExtUtils::CBuilder"
as a "build_requires" element.
SAVING CONFIGURATION INFORMATION
Module::Build provides a very convenient way to save configuration
information that your installed modules (or your regression tests) can
access. If your Build process calls the "feature()" or "config_data()"
methods, then a "Foo::Bar::ConfigData" module will automatically be
created for you, where "Foo::Bar" is the "module_name" parameter as
passed to "new()". This module provides access to the data saved by
these methods, and a way to update the values. There is also a utility
script called "config_data" distributed with Module::Build that
provides a command line interface to this same functionality. See also
the generated "Foo::Bar::ConfigData" documentation, and the
"config_data" script's documentation, for more information.
STARTING MODULE DEVELOPMENT
When starting development on a new module, it's rarely worth your time
to create a tree of all the files by hand. Some automatic module-
creators are available: the oldest is "h2xs", which has shipped with
perl itself for a long time. Its name reflects the fact that modules
were originally conceived of as a way to wrap up a C library (thus the
"h" part) into perl extensions (thus the "xs" part).
These days, "h2xs" has largely been superseded by modules like
"ExtUtils::ModuleMaker", and "Module::Starter". They have varying
degrees of support for "Module::Build".
AUTOMATION
One advantage of Module::Build is that since it's implemented as Perl
methods, you can invoke these methods directly if you want to install a
module non-interactively. For instance, the following Perl script will
invoke the entire build/install procedure:
my $build = Module::Build->new(module_name => 'MyModule');
$build->dispatch('build');
$build->dispatch('test');
$build->dispatch('install');
If any of these steps encounters an error, it will throw a fatal
exception.
You can also pass arguments as part of the build process:
my $build = Module::Build->new(module_name => 'MyModule');
$build->dispatch('build');
$build->dispatch('test', verbose => 1);
$build->dispatch('install', sitelib => '/my/secret/place/');
Building and installing modules in this way skips creating the "Build"
script.
MIGRATION
Note that if you want to provide both a Makefile.PL and a Build.PL for
your distribution, you probably want to add the following to
"WriteMakefile" in your Makefile.PL so that "MakeMaker" doesn't try to
run your Build.PL as a normal .PL file:
PL_FILES => {},
You may also be interested in looking at the "Module::Build::Compat"
module, which can automatically create various kinds of Makefile.PL
compatibility layers.
AUTHOR
Ken Williams <kwilliams AT cpan.org>
Development questions, bug reports, and patches should be sent to the
Module-Build mailing list at <module-build AT perl.org>.
Bug reports are also welcome at
<http://rt.cpan.org/NoAuth/Bugs.html?Dist=Module-Build>;.
The latest development version is available from the Git repository at
<https://github.com/Perl-Toolchain-Gang/Module-Build>;
SEE ALSO
perl(1), Module::Build(3), Module::Build::API(3),
Module::Build::Cookbook(3), ExtUtils::MakeMaker(3), YAML(3)
META.yml Specification: CPAN::META::Spec
<http://www.dsmit.com/cons/>;
<http://search.cpan.org/dist/PerlBuildSystem/>;
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