/ 
Module-Build-0.03
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/ Module::Build

NAME

Module::Build - Build and install Perl modules

SYNOPSIS

Standard process for building & installing modules:

  perl Build.PL
  ./Build             # this script created by 'perl Build.PL'
  ./Build test
  ./Build install

Other actions:

  ./Build clean
  ./Build realclean
  ./Build fakeinstall
  ./Build dist
  ./Build help

DESCRIPTION

This is a very alpha version of a new module set I've been working on, Module::Build. It is meant to be a replacement for ExtUtils::MakeMaker.

To install Module::Build, and any other module that uses Module::Build for its installation process, do the following:

perl Build.PL
./Build
./Build test
./Build install

Other actions so far include:

./Build clean
./Build realclean
./Build fakeinstall
./Build dist
./Build help

It's like the MakeMaker metaphor, except that Build is a Perl script, not a Makefile. State is stored in a directory called _build/.

Any customization can be done simply by subclassing Module::Build and adding a method called (for example) ACTION_test, overriding the default action. You could also add a method called ACTION_whatever, and then you could perform the action ./Build whatever.

More actions will certainly be added to the core - it should be easy to do everything that the MakeMaker process can do. It's going to take some time, though. In the meantime, I may implement some pass-through functionality so that unknown actions are passed to MakeMaker.

METHODS

I list here some of the most important methods in the Module::Build. As the interface is still very unstable, I must ask that for now, you read the source to get more information on them. Normally you won't need to deal with these methods unless you want to subclass Module::Build. But since one of the reasons I created this module in the first place was so that subclassing is possible (and easy), I will certainly write more docs as the interface stabilizes.

  • Module::Build->new(...)

    Creates a new Module::Build object. The module_name argument is required, and should be a string like 'Your::Module'. The module_version argument is optional - if not explicitly provided, we'll look for the version string in the module specified by module_name, parsing it out according to the same rules as ExtUtils::MakeMaker and CPAN.pm.

  • add_to_cleanup

    A Module::Build method may call $self->add_to_cleanup(@files) to tell Module::Build that certain files should be removed when the user performs the Build clean action. I decided to make this a dynamic method, rather than a static list of files, because these static lists can get difficult to manage. I preferred to keep the responsibility for registering temporary files close to the code that creates them.

  • resume

    You'll probably never call this method directly, it's only called from the auto-generated Build script. The new() method is only called once, when the user runs perl Build.PL. Thereafter, when the user runs Build test or another action, the Module::Build object is created using the resume() method.

  • dispatch

    This method is also called from the auto-generated Build script. It parses the command-line arguments into an action and an argument list, then calls the appropriate routine to handle the action. Currently (though this may change), an action foo will invoke the ACTION_foo method. All arguments (including everything mentioned in ACTIONS below) are contained in the $self->{args} hash reference.

ACTIONS

There are some general principles at work here. First, each task when building a module is called an "action". These actions are listed above; they correspond to the building, testing, installing, packaging, etc. tasks.

Second, arguments are processed in a very systematic way. Arguments are always key=value pairs. They may be specified at perl Build.PL time (i.e. perl Build.PL sitelib=/my/secret/place), in which case their values last for the lifetime of the Build script. They may also be specified when executing a particular action (i.e. Build test verbose=1, in which case their values last only for the lifetime of that command. The build process also relies heavily on the Config.pm module, and all the key=value pairs in Config.pm are merged into the mix too. The precedence of parameters is, from highest to lowest: per-action parameters, Build.PL parameters, and Config.pm parameters.

The following build actions are provided by default.

  • build

    This is analogous to the MakeMaker 'make' target with no arguments. By default it just creates a blib/ directory and copies any .pm and .pod files from your lib/ directory into the blib/ directory. It also compiles any .xs files from lib/ and places them in blib/. Of course, you need a working C compiler (preferably the same one that built perl itself) for this to work properly.

    Note that in contrast to MakeMaker, this module only (currently) handles .pm, .pod, and .xs files. They must all be in the lib/ directory, in the directory structure that they should have when installed.

    If you run the Build script without any arguments, it runs the build action.

    In future releases of Module::Build the build action should be able to process .PL files. The .xs support is currently in alpha. Please let me know if it works for you.

  • test

    This will use Test::Harness to run any regression tests and report their results. Tests can be defined in the standard places: a file called test.pl in the top-level directory, or several files ending with .t in a t/ directory.

    If you want tests to be 'verbose', i.e. show details of test execution rather than just summary information, pass the argument verbose=1.

  • clean

    This action will clean up any files that the build process may have created, including the blib/ directory (but not including the _build/ directory and the Build script itself).

  • realclean

    This action is just like the clean action, but also removes the _build directory and the Build script. If you run the realclean action, you are essentially starting over, so you will have to re-create the Build script again.

  • install

    This action will use ExtUtils::Install to install the files from blib/ into the correct system-wide module directory. The directory is determined from the sitelib entry in the Config.pm module. To install into a different directory, pass a different value for the sitelib parameter, like so:

    Build install sitelib=/my/secret/place/

    Alternatively, you could specify the sitelib parameter when you run the Build.PL script:

    perl Build.PL sitelib=/my/secret/place/

    Under normal circumstances, you'll need superuser privileges to install into the default sitelib directory.

  • fakeinstall

    This is just like the install action, but it won't actually do anything, it will just report what it would have done if you had actually run the install action.

  • dist

    This action is helpful for module authors who want to package up their module for distribution through a medium like CPAN. It will create a tarball and compress it using GZIP compression.

  • help

    This action will simply print out a message that is meant to help you use the build process. It will show you a list of available build actions too.

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.)

Right now, if you want to subclass Module::Build you must do so by including an actual .pm file somewhere in your distribution. There will be much better ways to do this in the future. Can't do everything at once...

MOTIVATIONS

There are several reasons I wanted to start over, and not just fix what I didn't like about MakeMaker:

  • I don't like the core idea of MakeMaker, namely that make should be involved in the build process. Here are my reasons:

    +

    When a person is installing a Perl module, what can you assume about their environment? Can you assume they have make? No, but you can assume they have some version of Perl.

    +

    When a person is writing a Perl module for intended distribution, can you assume that they know how to build a Makefile, so they can customize their build process? No, but you can assume they know Perl, and could customize that way.

    For years, these things have been a barrier to people getting the build/install process to do what they want.

  • There are several architectural decisions in MakeMaker that make it very difficult to customize its behavior. For instance, when using MakeMaker you do use MakeMaker, but the object created in WriteMakefile() is actually blessed into a package name that's created on the fly, so you can't simply subclass ExtUtils::MakeMaker. There is a workaround MY package that lets you override certain MakeMaker methods, but only certain explicitly predefined (by MakeMaker) methods can be overridden. Also, the method of customization is very crude: you have to modify a string containing the Makefile text for the particular target.

  • It is risky to make major changes to MakeMaker, since it does so many things, is so important, and generally works. Module::Build is an entirely seperate package so that I can work on it all I want, without worrying about backward compatibility.

  • Finally, Perl is said to be a language for system administration. Could it really be the case that Perl isn't up to the task of building and installing software? Absolutely not - see the Cons package for one example, at http://www.dsmit.com/cons/ .

Please contact me if you have any questions or ideas.

AUTHOR

Ken Williams, ken@forum.swarthmore.edu

SEE ALSO

perl(1), ExtUtils::MakeMaker(3)

http://www.dsmit.com/cons/