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David Golden
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NAME

inc::latest - use modules bundled in inc/ if they are newer than installed ones

VERSION

version 0.500

SYNOPSIS

  # in Makefile.PL or Build.PL
  use inc::latest 'Some::Configure::Prereq';

DESCRIPTION

WARNING -- THIS IS AN EXPERIMENTAL MODULE. It was originally bundled (as an experiment) with Module::Build and has been split out for more general use.

The inc::latest module helps bootstrap configure-time dependencies for CPAN distributions. These dependencies get bundled into the inc directory within a distribution and are used by Makefile.PL or Build.PL.

Arguments to inc::latest are module names that are checked against both the current @INC array and against specially-named directories in inc. If the bundled version is newer than the installed one (or the module isn't installed, then, the bundled directory is added to the start of @INC and the module is loaded from there.

There are actually two variations of inc::latest -- one for authors and one for the inc directory. For distribution authors, the inc::latest installed in the system will record modules loaded via inc::latest and can be used to create the bundled files in inc, including writing the second variation as inc/latest.pm.

This second inc::latest is the one that is loaded in a distribution being installed (e.g. from Makefile.PL or Build.PL). This bundled inc::latest is the one that determines which module to load.

Special notes on bundling

The inc::latest module creates bundled directories based on the packlist file of an installed distribution. Even though inc::latest takes module name arguments, it is better to think of it as bundling and making available entire distributions. When a module is loaded through inc::latest, it looks in all bundled distributions in inc/ for a newer module than can be found in the existing @INC array.

Thus, the module-name provided should usually be the "top-level" module name of a distribution, though this is not strictly required. inc::latest has a number of heuristics to discover module names, allowing users to do things like this:

  use inc::latest 'Devel::AssertOS::Unix';

even though Devel::AssertOS::Unix is contained within the Devel-CheckOS distribution.

At the current time, packlists are required. Thus, bundling dual-core modules may require a 'forced install' over versions in the latest version of perl in order to create the necessary packlist for bundling.

Managing dependency chains

Before bundling a distribution you must ensure that all prerequisites are also bundled and load in the correct order.

For example, if you need Wibble, but Wibble depends on Wobble, and you have bundled Module::Build, your Build.PL might look like this:

  use inc::latest 'Wobble';
  use inc::latest 'Wibble';
  use inc::latest 'Module::Build';

  Module::Build->new(
    module_name => 'Foo::Bar',
    license => 'perl',
  )->create_build_script;

Authors are strongly suggested to limit the bundling of additional dependencies if at all possible and to carefully test their distribution tarballs before uploading to CPAN.

USAGE

As bundled in inc/

Using "Author-mode", a special stub module will be created in your distribute directory as inc/latest.pm. In your Makefile.PL or Build.PL, you can then load inc::latest to load bundled modules.

When calling use, the bundled inc::latest takes a single module name and optional arguments to pass to that module's own import method.

  use inc::latest 'Foo::Bar' qw/foo bar baz/;

The implementation is private. Only the import method is public.

Author-mode

When you have inc::latest installed from CPAN, then you are in author-mode if any of the Author-mode methods are available. For example:

  if ( inc::latest->can('write') ) {
    inc::latest->write('inc');
  }

Using author-mode, you can create the stub inc/latest.pm and bundle modules into inc.

loaded_modules()
  my @list = inc::latest->loaded_modules;

This takes no arguments and always returns a list of module names requested for loading via "use inc::latest 'MODULE'", regardless of whether the load was successful or not.

write()
  inc::latest->write( 'inc' );

This writes the bundled version of inc::latest to the directory name given as an argument. It almost all cases, it should be 'inc'.

bundle_module()
  for my $mod ( inc::latest->loaded_modules ) {
    inc::latest->bundle_module($mod, $dir);
  }

If $mod corresponds to a packlist, then this function creates a specially-named directory in $dir and copies all .pm files from the modlist to the new directory (which almost always should just be 'inc'). For example, if Foo::Bar is the name of the module, and $dir is 'inc', then the directory would be 'inc/inc_Foo-Bar' and contain files like this:

  inc/inc_Foo-Bar/Foo/Bar.pm

Currently, $mod must have a packlist. If this is not the case (e.g. for a dual-core module), then the bundling will fail. You may be able to create a packlist by forced installing the module on top of the version that came with core Perl.

SUPPORT

Bugs / Feature Requests

Please report any bugs or feature requests through the issue tracker at https://github.com/dagolden/inc-latest/issues. You will be notified automatically of any progress on your issue.

Source Code

This is open source software. The code repository is available for public review and contribution under the terms of the license.

https://github.com/dagolden/inc-latest

  git clone https://github.com/dagolden/inc-latest.git

AUTHORS

  • David Golden <dagolden@cpan.org>

  • Eric Wilhelm <ewilhelm@cpan.org>

COPYRIGHT AND LICENSE

This software is Copyright (c) 2009 by David Golden.

This is free software, licensed under:

  The Apache License, Version 2.0, January 2004