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 This illustrates initial configuration and the running of three 'actions'. In this case the actions run are 'build' (the default action), 'test', and 'install'. Actions defined so far include: build help clean install dist manifest distcheck realclean distclean skipcheck distdir test disttest testdb fakeinstall You can run the 'help' action for a complete list of actions. 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 'test' 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. For information on providing backward compatibility with "ExtUtils::MakeMaker", see the Module::Build::Compat manpage. METHODS I list here some of the most important methods in "Module::Build". 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. Arguments to the new() method are listed below. The only required argument is the "module_name" argument. * module_name The "module_name" argument is required, and should be a string like "'Your::Module'". We use it for several purposes, including finding the version string for this distribution, and creating a suitably-named distribution directory. * module_version 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". * module_version_from Allows you to specify an alternate file for finding the module version, instead of looking in the file specified by "module_name". * prereq An optional "prereq" argument specifies any module prerequisites that the current module depends on. The prerequisites are given in a hash reference, where the keys are the module names and the values are version specifiers: prereq => {Foo::Module => '2.4', Bar::Module => 0, Ken::Module => '>= 1.2, != 1.5, < 2.0'}, These three 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. One note: currently we don't actually *requre* the user to have these modules installed, we just strongly urge. In the future we may require it. There's now a "recommended" section for things that aren't absolutely required. * recommended This is just like the "prereq" argument, except that modules in this list aren't essential, just a good idea. We'll just print a friendly warning if one of these modules aren't found, but we'll continue running. * c_source 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. * autosplit 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. $m->check_installed_version($module, $version) This method returns true or false, depending on whether (at least) version "$version" of module "$module" is installed. The "$module" argument is given as a string like ""Data::Dumper"", and the "$version" argument can take any of the forms described in the prereq manpage above. This allows very fine-grained version checking. If the check fails, we return false and set "$@" to an informative error message. If the check succeeds, the return value is the actual version of "$module" installed on the system. This allows you to do the following: my $installed = $m->check_installed_version('DBI', '1.15'); if ($installed) { print "Congratulations, version $installed of DBI is installed.\n"; } else { die "Sorry, you must install DBI.\n"; } If "$version" is any nontrue value (notably zero) and any version of "$module" is installed, we return true. In this case, if "$module" doesn't define a version, or if its version is zero, we return the special value "0 but true", which is numerically zero, but logically true. 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. Per-action command-line parameters take precedence over parameters specified at "perl Build.PL" time. The build process also relies heavily on the "Config.pm" module, and all the key=value pairs in "Config.pm" are available in "$self->{config}". If the user wishes to override any of the values in "Config.pm", she may specify them like so: perl Build.PL config='siteperl=/foo perlpath=/wacky/stuff' Not the greatest interface, I'm looking for alternatives. Speak now! Maybe: perl Build.PL config-siteperl=/foo config-perlpath=/wacky/stuff or something. The following build actions are provided by default. * 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. * build If you run the "Build" script without any arguments, it runs the "build" action. This is analogous to the MakeMaker 'make all' target. 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 (probably the same one that built perl itself) for this to work properly. The "build" action also runs any ".PL" files in your lib/ directory. Typically these create other files, named the same but without the ".PL" ending. For example, a file lib/Foo/Bar.pm.PL could create the file lib/Foo/Bar.pm. The ".PL" files are processed first, so any ".pm" files (or other kinds that we deal with) will get copied correctly. If your ".PL" scripts don't create any files, or if they create files with unexpected names, or even if they create multiple files, you should tell us that so that we can clean up properly after these created files. Use the "PL_files" parameter to "new()": PL_files => { 'lib/Foo/Bar_pm.PL' => 'lib/Foo/Bar.pm', 'lib/something.PL' => ['/lib/something', '/lib/else'], 'lib/funny.PL' => [] } Note that in contrast to MakeMaker, the "build" action only (currently) handles ".pm", ".pod", ".PL", and ".xs" files. They must all be in the "lib/" directory, in the directory structure that they should have when installed. We also handle ".c" files that can be in the place of your choosing - see the "c_source" argument to "new()". The ".xs" support is currently in alpha. Please let me know whether 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". If you want to run tests under the perl debugger, pass the argument "debugger=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. * testdb This is a synonym for the 'test' action with the "debugger=1" argument. * 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. * 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. The following is a reasonable MANIFEST.SKIP starting point, you can add your own stuff to it: ^_build ^Build$ ^blib ~$ \.bak$ ^MANIFEST\.SKIP$ CVS See the the distcheck manpage and the skipcheck manpage actions if you want to find out what the "manifest" action would do, without actually doing anything. * 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. * distcheck Reports which files are in the build directory but not in the MANIFEST file, and vice versa. (See the manifest manpage for details) * skipcheck Reports which files are skipped due to the entries in the MANIFEST.SKIP file (See the manifest manpage for details) * distclean Performs the 'realclean' action and then the 'distcheck' action. * distdir Creates a directory called "$(DISTNAME)-$(VERSION)" (if that directory already exists, it will be removed first). Then copies all the files listed in the MANIFEST file to that directory. This directory is what people will see when they download your distribution and unpack it. * disttest Performs the 'distdir' action, then switches into that directory and runs a "perl Build.PL", followed by the 'build' and 'test' actions in that directory. 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.) 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 qw(/nonstandard/library/path); use My::Builder; # Or whatever you want to call it my $m = My::Builder->new(module_name => 'Next::Big::Thing'); $m->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 propogated to the Build script, so that My::Builder can be found when running build actions. 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 my $class = Module::Build->subclass ( class => 'My::Builder', code => q{ sub ACTION_foo { print "I'm fooing to death!\n"; } }, ); my $m = $class->new(module_name => 'Module::Build'); $m->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. 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? Even if that software is a bunch of stupid little ".pm" files? Are you getting riled up yet?? Please contact me if you have any questions or ideas. TO DO 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 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. - make man pages and install them. - append to perllocal.pod - write .packlist in appropriate location (needed for un-install) - write dependency list in _build AUTHOR Ken Williams, ken@mathforum.org SEE ALSO perl(1), ExtUtils::MakeMaker(3) http://www.dsmit.com/cons/