Module::Build(3)

NAME
Module::Build - Build and install Perl modules

SYNOPSIS
Standard process for building & installing modules:

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

Or, if you're on a platform (like DOS or Windows) that doesn't require the "./" notation, you can do this:

  perl Build.PL
  Build
  Build test
  Build install

DESCRIPTION
"Module::Build" is a system for building, testing, and installing Perl modules. It is meant to be an alternative to "ExtUtils::MakeMaker". Developers may alter the behavior of the module through subclassing in a much more straightforward way than with "MakeMaker". It also does not require a "make" on your system - most of the "Module::Build" code is pure-perl and written in a very cross-platform way. In fact, you don't even need a shell, so even platforms like MacOS (traditional) can use it fairly easily. Its only prerequisites are modules that are included with perl 5.6.0, and it works fine on perl 5.005 if you can install a few additional modules.

See "MOTIVATIONS" for more comparisons between "ExtUtils::MakeMaker" and "Module::Build".

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

  perl Build.PL       # 'Build.PL' script creates the 'Build' script
  ./Build             # Need ./ to ensure we're using this "Build" script
  ./Build test        # and not another one that happens to be in the PATH
  ./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'. Other actions defined so far include:

  build                          install
  clean                          manifest
  code                           manpages
  config_data                    ppd
  diff                           ppmdist
  dist                           prereq_report
  distcheck                      pure_install
  distclean                      realclean
  distdir                        skipcheck
  distmeta                       test
  distsign                       testcover
  disttest                       testdb
  docs                           testpod
  fakeinstall                    testpodcoverage
  help                           versioninstall
  html

You can run the 'help' action for a complete list of actions.

GUIDE TO DOCUMENTATION
The documentation for "Module::Build" is broken up into three sections:

General Usage (Module::Build)
    This is the document you are currently reading. It describes basic usage and background information. Its main purpose is to assist the user who wants to learn how to invoke and control "Module::Build" scripts at the command line.

Authoring Reference (Module::Build::Authoring)
    This document describes the structure and organization of "Module::Build", and the relevant concepts needed by authors who are writing Build.PL scripts for a distribution or controlling "Module::Build" processes programmatically.

API Reference (Module::Build::API)
    This is a reference to the "Module::Build" API.

Cookbook (Module::Build::Cookbook)
    This document demonstrates how to accomplish many common tasks. It covers general command line usage and authoring of Build.PL scripts. Includes working examples.

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 destdir=/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 cc=gcc --config ld=gcc

The following build actions are provided by default.

build
    [version 0.01]

    If you run the "Build" script without any arguments, it runs the "build" action, which in turn runs the "code" and "docs" actions.

    This is analogous to the MakeMaker 'make all' target.

clean
    [version 0.01]

    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).

code
    [version 0.20]

    This action builds your codebase.

    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 the compilation to work properly.

    The "code" 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.

config_data
    [version 0.26]

    ...

diff
    [version 0.14]

    This action will compare the files about to be installed with their installed counterparts. For .pm and .pod files, a diff will be shown (this currently requires a 'diff' program to be in your PATH). For other files like compiled binary files, we simply report whether they differ.

    A "flags" parameter may be passed to the action, which will be passed to the 'diff' program. Consult your 'diff' documentation for the parameters it will accept - a good one is "-u":

      ./Build diff flags=-u

dist
    [version 0.02]

    This action is helpful for module authors who want to package up their module for source distribution through a medium like CPAN. It will create a tarball of the files listed in MANIFEST and compress the tarball using GZIP compression.

    By default, this action will use the external "tar" and "gzip" executables on Unix-like platforms, and the "Archive::Tar" module elsewhere. However, you can force it to use whatever executable you want by supplying an explicit "tar" (and optional "gzip") parameter:

      ./Build dist --tar C:\path\to\tar.exe --gzip C:\path\to\zip.exe

distcheck
    [version 0.05]

    Reports which files are in the build directory but not in the MANIFEST file, and vice versa. (See manifest for details.)

distclean
    [version 0.05]

    Performs the 'realclean' action and then the 'distcheck' action.

distdir
    [version 0.05]

    Creates a "distribution directory" named "$dist_name-$dist_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 the distribution tarball is created from.

distmeta
    [version 0.21]

    Creates the META.yml file that describes the distribution.

    META.yml is a file containing various bits of "metadata" about the distribution. The metadata includes the distribution name, version, abstract, prerequisites, license, and various other data about the distribution. This file is created as META.yml in YAML format. It is recommended that the "YAML" module be installed to create it. If the "YAML" module is not installed, an internal module supplied with Module::Build will be used to write the META.yml file, and this will most likely be fine.

    META.yml file must also be listed in MANIFEST - if it's not, a warning will be issued.

    The current version of the META.yml specification can be found at <http://module-build.sourceforge.net/META-spec-v1.2.html>

distsign
    [version 0.16]

    Uses "Module::Signature" to create a SIGNATURE file for your distribution, and adds the SIGNATURE file to the distribution's MANIFEST.

disttest
    [version 0.05]

    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.

docs
    [version 0.20]

    This will generate documentation (e.g. Unix man pages and html documents) for any installable items under blib/ that contain POD. If there are no "bindoc" or "libdoc" installation targets defined (as will be the case on systems that don't support Unix manpages) no action is taken for manpages. If there are no "binhtml" or "libhtml" installation targets defined no action is taken for html documents.

fakeinstall
    [version 0.02]

    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.

help
    [version 0.03]

    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.

    With an optional argument specifying an action name (e.g. "Build help test"), the 'help' action will show you any POD documentation it can find for that action.

html
    [version 0.26]

    This will generate HTML documentation for any binary or library files under blib/ that contain POD. The HTML documentation will only be installed if the install paths can be determined from values in "Config.pm". You can also supply or override install paths on the command line by specifying "install_path" values for the "binhtml" and/or "libhtml" installation targets.

install
    [version 0.01]

    This action will use "ExtUtils::Install" to install the files from "blib/" into the system. See "INSTALL PATHS" for details about how Module::Build determines where to install things, and how to influence this process.

    If you want the installation process to look around in @INC for other versions of the stuff you're installing and try to delete it, you can use the "uninst" parameter, which tells "ExtUtils::Install" to do so:

      ./Build install uninst=1

    This can be a good idea, as it helps prevent multiple versions of a module from being present on your system, which can be a confusing situation indeed.

manifest
    [version 0.05]

    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 distcheck and skipcheck actions if you want to find out what the "manifest" action would do, without actually doing anything.

manpages
    [version 0.28]

    This will generate man pages for any binary or library files under blib/ that contain POD. The man pages will only be installed if the install paths can be determined from values in "Config.pm". You can also supply or override install paths by specifying there values on the command line with the "bindoc" and "libdoc" installation targets.

ppd [version 0.20]

    Build a PPD file for your distribution.

    This action takes an optional argument "codebase" which is used in the generated ppd file to specify the (usually relative) URL of the distribution. By default, this value is the distribution name without any path information.

    Example:

      ./Build ppd --codebase "MSWin32-x86-multi-thread/Module-Build-0.21.tar.gz"

ppmdist
    [version 0.23]

    Generates a PPM binary distribution and a PPD description file. This action also invokes the 'ppd' action, so it can accept the same "codebase" argument described under that action.

    This uses the same mechanism as the "dist" action to tar & zip its output, so you can supply "tar" and/or "gzip" parameters to affect the result.

prereq_report
    [version 0.28]

    This action prints out a list of 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.

pure_install
    [version 0.28]

    This action is identical to the "install" action. In the future, though, if "install" starts writing to the file file $(INSTALLARCHLIB)/perllocal.pod, "pure_install" won't, and that will be the only difference between them.

realclean
    [version 0.01]

    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.

skipcheck
    [version 0.05]

    Reports which files are skipped due to the entries in the MANIFEST.SKIP file (See manifest for details)

test
    [version 0.01]

    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.

    To override the choice of tests to run, you may pass a "test_files" argument whose value is a whitespace-separated list of test scripts to run. This is especially useful in development, when you only want to run a single test to see whether you've squashed a certain bug yet:

      ./Build test --test_files t/something_failing.t

    You may also pass several "test_files" arguments separately:

      ./Build test --test_files t/one.t --test_files t/two.t

    or use a "glob()"-style pattern:

      ./Build test --test_files 't/01-*.t'

testcover
    [version 0.26]

    Runs the "test" action using "Devel::Cover", generating a code-coverage report showing which parts of the code were actually exercised during the tests.

    To pass options to "Devel::Cover", set the $DEVEL_COVER_OPTIONS environment variable:

      DEVEL_COVER_OPTIONS=-ignore,Build ./Build testcover

testdb
    [version 0.05]

    This is a synonym for the 'test' action with the "debugger=1" argument.

testpod
    [version 0.25]

    This checks all the files described in the "docs" action and produces "Test::Harness"-style output. If you are a module author, this is useful to run before creating a new release.

testpodcoverage
    [version 0.28]

    This checks the pod coverage of the distribution and produces "Test::Harness"-style output. If you are a module author, this is useful to run before creating a new release.

versioninstall
    [version 0.16]

    ** Note: since "only.pm" is so new, and since we just recently added support for it here too, this feature is to be considered experimental. **

    If you have the "only.pm" module installed on your system, you can use this action to install a module into the version-specific library trees. This means that you can have several versions of the same module installed and "use" a specific one like this:

      use only MyModule => 0.55;

    To override the default installation libraries in "only::config", specify the "versionlib" parameter when you run the "Build.PL" script:

      perl Build.PL --versionlib /my/version/place/

    To override which version the module is installed as, specify the "versionlib" parameter when you run the "Build.PL" script:

      perl Build.PL --version 0.50

    See the "only.pm" documentation for more information on version-specific installs.

OPTIONS

  Command Line Options
The following options can be used during any invocation of "Build.PL" or the Build script, during any action. For information on other options specific to an action, see the documentation for the respective action.

NOTE: There is some preliminary support for options to use the more familiar long option style. Most options can be preceded with the "--" long option prefix, and the underscores changed to dashes (e.g. --use-rcfile). Additionally, the argument to boolean options is optional, and boolean options can be negated by prefixing them with 'no' or 'no-' (e.g. --noverbose or --no-verbose).

quiet
    Suppress informative messages on output.

use_rcfile
    Load the ~/.modulebuildrc option file. This option can be set to false to prevent the custom resource file from being loaded.

verbose
    Display extra information about the Build on output.

allow_mb_mismatch
    Suppresses the check upon startup that the version of Module::Build we're now running under is the same version that was initially invoked when building the distribution (i.e. when the "Build.PL" script was first run). Use with caution.

  Default Options File (.modulebuildrc)
[version 0.28]

When Module::Build starts up, it will look first for a file, $ENV{HOME}/.modulebuildrc. If it's not found there, it will look in the the .modulebuildrc file in the directories referred to by the environment variables "HOMEDRIVE" + "HOMEDIR", "USERPROFILE", "APPDATA", "WINDIR", "SYS$LOGIN". If the file exists, the options specified there will be used as defaults, as if they were typed on the command line. The defaults can be overridden by specifying new values on the command line.

The action name must come at the beginning of the line, followed by any amount of whitespace and then the options. Options are given the same as they would be on the command line. They can be separated by any amount of whitespace, including newlines, as long there is whitespace at the beginning of each continued line. Anything following a hash mark ("#") is considered a comment, and is stripped before parsing. If more than one line begins with the same action name, those lines are merged into one set of options.

Besides the regular actions, there are two special pseudo-actions: the key "*" (asterisk) denotes any global options that should be applied to all actions, and the key 'Build_PL' specifies options to be applied when you invoke "perl Build.PL".

  *        verbose=1   # global options
  diff     flags=-u
  install  --install_base /home/ken
           --install_path html=/home/ken/docs/html

If you wish to locate your resource file in a different location, you can set the environment variable 'MODULEBUILDRC' to the complete absolute path of the file containing your options.

INSTALL PATHS
[version 0.19]

When you invoke Module::Build's "build" action, it needs to figure out where to install things. The nutshell version of how this works is that default installation locations are determined from Config.pm, and they may be overridden by using the "install_path" parameter. An "install_base" parameter lets you specify an alternative installation root like /home/foo, and a "destdir" lets you specify a temporary installation directory like /tmp/install in case you want to create bundled-up installable packages.

Natively, Module::Build provides default installation locations for the following types of installable items:

lib Usually pure-Perl module files ending in .pm.

arch
    "Architecture-dependent" module files, usually produced by compiling XS, Inline, or similar code.

script
    Programs written in pure Perl. In order to improve reuse, try to make these as small as possible - put the code into modules whenever possible.

bin "Architecture-dependent" executable programs, i.e. compiled C code or something. Pretty rare to see this in a perl distribution, but it happens.

bindoc
    Documentation for the stuff in "script" and "bin". Usually generated from the POD in those files. Under Unix, these are manual pages belonging to the 'man1' category.

libdoc
    Documentation for the stuff in "lib" and "arch". This is usually generated from the POD in .pm files. Under Unix, these are manual pages belonging to the 'man3' category.

binhtml
    This is the same as "bindoc" above, but applies to html documents.

libhtml
    This is the same as "bindoc" above, but applies to html documents.

Four other parameters let you control various aspects of how installation paths are determined:

installdirs
    The default destinations for these installable things come from entries in your system's "Config.pm". You can select from three different sets of default locations by setting the "installdirs" parameter as follows:

                              'installdirs' set to:
                       core          site                vendor

                  uses the following defaults from Config.pm:

      lib     => installprivlib  installsitelib      installvendorlib
      arch    => installarchlib  installsitearch     installvendorarch
      script  => installscript   installsitebin      installvendorbin
      bin     => installbin      installsitebin      installvendorbin
      bindoc  => installman1dir  installsiteman1dir  installvendorman1dir
      libdoc  => installman3dir  installsiteman3dir  installvendorman3dir
      binhtml => installhtml1dir installsitehtml1dir installvendorhtml1dir [*]
      libhtml => installhtml3dir installsitehtml3dir installvendorhtml3dir [*]

      * Under some OS (eg. MSWin32) the destination for html documents is
        determined by the C<Config.pm> entry C<installhtmldir>.

    The default value of "installdirs" is "site". If you're creating vendor distributions of module packages, you may want to do something like this:

      perl Build.PL --installdirs vendor

    or

      ./Build install --installdirs vendor

    If you're installing an updated version of a module that was included with perl itself (i.e. a "core module"), then you may set "installdirs" to "core" to overwrite the module in its present location.

    (Note that the 'script' line is different from MakeMaker - unfortunately there's no such thing as "installsitescript" or "installvendorscript" entry in "Config.pm", so we use the "installsitebin" and "installvendorbin" entries to at least get the general location right. In the future, if "Config.pm" adds some more appropriate entries, we'll start using those.)

install_path
    Once the defaults have been set, you can override them.

    On the command line, that would look like this:

      perl Build.PL --install_path lib=/foo/lib --install_path arch=/foo/lib/arch

    or this:

      ./Build install --install_path lib=/foo/lib --install_path arch=/foo/lib/arch

install_base
    You can also set the whole bunch of installation paths by supplying the "install_base" parameter to point to a directory on your system. For instance, if you set "install_base" to "/home/ken" on a Linux system, you'll install as follows:

      lib     => /home/ken/lib/perl5
      arch    => /home/ken/lib/perl5/i386-linux
      script  => /home/ken/bin
      bin     => /home/ken/bin
      bindoc  => /home/ken/man/man1
      libdoc  => /home/ken/man/man3
      binhtml => /home/ken/html
      libhtml => /home/ken/html

    Note that this is different from how MakeMaker's "PREFIX" parameter works. See "Why PREFIX is not recommended" for more details. "install_base" just gives you a default layout under the directory you specify, which may have little to do with the "installdirs=site" layout.

    The exact layout under the directory you specify may vary by system - we try to do the "sensible" thing on each platform.

destdir
    If you want to install everything into a temporary directory first (for instance, if you want to create a directory tree that a package manager like "rpm" or "dpkg" could create a package from), you can use the "destdir" parameter:

      perl Build.PL --destdir /tmp/foo

    or

      ./Build install --destdir /tmp/foo

    This will effectively install to "/tmp/foo/$sitelib", "/tmp/foo/$sitearch", and the like, except that it will use "File::Spec" to make the pathnames work correctly on whatever platform you're installing on.

prefix
    Provided for compatibility with ExtUtils::MakeMaker's PREFIX argument. "prefix" should be used when you wish Module::Build to install your modules, documentation and scripts in the same place ExtUtils::MakeMaker does.

    The following are equivalent.

        perl Build.PL --prefix /tmp/foo
        perl Makefile.PL PREFIX=/tmp/foo

    Because of the very complex nature of the prefixification logic, the behavior of PREFIX in MakeMaker has changed subtly over time. Module::Build's --prefix logic is equivalent to the PREFIX logic found in ExtUtils::MakeMaker 6.30.

    If you do not need to retain compatibility with ExtUtils::MakeMaker or are starting a fresh Perl installation we recommand you use "install_base" instead (and "INSTALL_BASE" in ExtUtils::MakeMaker). See "Instaling in the same location as ExtUtils::MakeMaker" in Module::Build::Cookbook for further information.

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 ExtUtils::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 preselected (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. Since these strings aren't documented, and can't be documented (they take on different values depending on the platform, version of perl, version of MakeMaker, etc.), you have no guarantee that your modifications will work on someone else's machine or after an upgrade of MakeMaker or perl.

•   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 separate 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 that just need to be copied from one place to another? My sense was that we could design a system to accomplish this in a flexible, extensible, and friendly manner. Or die trying.

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.

 - append to perllocal.pod
 - add a 'plugin' functionality

AUTHOR
Ken Williams <kwilliams@cpan.org>

Development questions, bug reports, and patches should be sent to the Module-Build mailing list at <module-build@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 Subversion repository at <https://svn.perl.org/modules/Module-Build/trunk/>

COPYRIGHT
Copyright (c) 2001-2005 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.

SEE ALSO
perl(1), Module::Build::Cookbook(3), Module::Build::Authoring(3), Module::Build::API(3), ExtUtils::MakeMaker(3), YAML(3)

META.yml Specification: <http://module-build.sourceforge.net/META-spec-v1.2.html>

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

<http://search.cpan.org/dist/PerlBuildSystem/>