NAME Module::Build - Build and install Perl modules SYNOPSIS Standard process for building & installing modules: perl Build.PL ./Build ./Build test ./Build install DESCRIPTION This is a beta 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 # this script is created by 'perl Build.PL' ./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 short Perl script, not a long 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. * $m = 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'. An optional `c_source' argument specifies a directory which contains C source files that the rest of the build may depend on. Any `.c' files in the directory will be compiled to object files. The directory will be added to the search path during the compilation and linking phases of any C or XS files. An optional `autosplit' argument specifies a file which should be run through the `Autosplit::autosplit()' function. In general I don't consider this a great idea, and I may even go so far as to remove this feature later. Let me know if I shouldn't. * $m->add_to_cleanup A `Module::Build' method may call `$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. * Module::Build->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. * $m->dispatch This method is also called from the auto-generated `Build' script. It parses the command-line arguments into an action and an argument list, then calls the appropriate routine to handle the action. Currently (though this may change), an action `foo' will invoke the `ACTION_foo' method. All arguments (including everything mentioned in the ACTIONS manpage below) are contained in the `$self->{args}' hash reference. * $m->os_type If you're subclassing Module::Build and some code needs to alter its behavior based on the current platform, you may only need to know whether you're running on Windows, Unix, MacOS, VMS, etc. and not the fine-grained value of Perl's `$^O' variable. The `os_type()' method will return a string like `Windows', `Unix', `MacOS', `VMS', or whatever is appropriate. If you're running on an unknown platform, it will return `undef' - there shouldn't be many unknown platforms though. 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'. In addition, if a file called `visual.pl' exists in the top-level directory, this file will be executed as a Perl script and its output will be shown to the user. This is a good place to put speed tests or other tests that don't use the `Test::Harness' format for output. * 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 of the files listed in MANIFEST and compress the tarball using GZIP compression. * manifest This is an action intended for use by module authors, not people installing modules. It will bring the MANIFEST up to date with the files currently present in the distribution. You may use a MANIFEST.SKIP file to exclude certain files or directories from inclusion in the MANIFEST. MANIFEST.SKIP should contain a bunch of regular expressions, one per line. If a file in the distribution directory matches any of the regular expressions, it won't be included in the MANIFEST. (Note to self: it would be nice to have a 'fake_manifest' action that would just go through the motions of adding to MANIFEST but not actually do anything. Currently ExtUtils::Manifest doesn't support it, though.) * 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. 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 $m = new Module::Build (module_name => 'MyModule'); $m->dispatch('build'); $m->dispatch('test'); $m->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 $m = new Module::Build (module_name => 'MyModule'); $m->dispatch('build'); $m->dispatch('test', verbose => 1); $m->dispatch('install', sitelib => '/my/secret/place/'); Building and installing modules in this way skips creating the `Build' script. 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 the section on "/www.dsmit.com/cons/" in the http: manpage . Please contact me if you have any questions or ideas. TO DO Need to implement a prerequisite mechanism, similar to MakeMaker's `PREREQ_PM' stuff. There will also be a subclassing mechanism that doesn't require as much module infrastructure to use. Something like this: use Module::Build subclass => <<'EOF'; sub ACTION_foo { ... implement the 'foo' action ... } EOF The current method of relying on time stamps to determine whether a derived file is out of date isn't likely to scale well, since it requires tracing all dependencies backward, it runs into problems on NFS, and it's just generally flimsy. It would be better to use an MD5 signature or the like, if available. See `cons' for an example. The current dependency-checking for .xs files is prone to errors. You can make 'widowed' files by doing `Build', `perl Build.PL', and then `Build realclean'. Should be easy to fix, but it's got me wondering whether the dynamic declaration of dependencies is a good idea. AUTHOR Ken Williams, ken@forum.swarthmore.edu SEE ALSO perl(1), ExtUtils::MakeMaker(3) http://www.dsmit.com/cons/