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Specify prerequisites for optional features in your distribution
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README.pod

NAME

Dist::Zilla::Plugin::OptionalFeature - Specify prerequisites for optional features in your distribution

VERSION

version 0.021

SYNOPSIS

In your dist.ini:

    [OptionalFeature / XS_Support]
    -description = XS implementation (faster, requires a compiler)
    -prompt = 1
    Foo::Bar::XS = 1.002

DESCRIPTION

This plugin provides a mechanism for specifying prerequisites for optional features in metadata, which should cause CPAN clients to interactively prompt you regarding these features at install time (assuming interactivity is turned on: e.g. cpanm --interactive Foo::Bar).

The feature name and description are required. The name can be extracted from the plugin name.

You can specify requirements for different phases and relationships with:

    [OptionalFeature / Feature_name]
    -description = description
    -phase = test
    -relationship = requires
    Fitz::Fotz    = 1.23
    Text::SoundEx = 3

If not provided, -phase defaults to runtime, and -relationship to requires.

To specify feature requirements for multiple phases, provide them as separate plugin configurations (keeping the feature name and description constant):

    [OptionalFeature / Feature_name]
    -description = description
    -phase = runtime
    Foo::Bar = 0

    [OptionalFeature / Feature_name]
    -description = description
    -phase = test
    Foo::Baz = 0

NOTE: this doesn't seem to work properly with CPAN::Meta::Merge (used in Dist::Zilla since version 5.022).

It is possible that future versions of this plugin may allow a more compact way of providing sophisticated prerequisite specifications.

If the plugin name is the CamelCase concatenation of a phase and relationship (or just a relationship), it will set those parameters implicitly. If you use a custom name, but it does not specify the relationship, and you didn't specify either or both of -phase or -relationship, these values default to runtime and requires respectively.

The example below is equivalent to the synopsis example above, except for the name of the resulting plugin:

    [OptionalFeature]
    -name = XS_Support
    -description = XS implementation (faster, requires a compiler)
    -phase = runtime
    -relationship = requires
    Foo::Bar::XS = 1.002

NOTE: It is advised that you only specify one prerequisite for a given feature -- and if necessary, create a separate distribution to encapsulate the code needed to make that feature work (along with all of its dependencies). This allows external projects to declare a prerequisite not just on your distribution, but also a particular feature of that distribution.

PROMPTING

At the moment it doesn't appear that any CPAN clients properly support optional_feature metadata and interactively prompt the user with the information therein. Therefore, prompting is added directly to Makefile.PL when the -relationship is requires. (It doesn't make much sense to prompt for recommends or suggests features, so prompting is omitted here.) You can also enable or disable this explicitly with the -prompt option. The prompt feature can only be used with Makefile.PL. If a Build.PL is detected in the build and =prompt is set, the build will fail.

As with any other interactive features, the installing user can bypass the prompts with PERL_MM_USE_DEFAULT=1. You may want to set this when running dzil build.

CONFIGURATION OPTIONS

This is mostly a restating of the information above.

  • -name

    The name of the optional feature, to be presented to the user. Can also be extracted from the plugin name.

  • -description

    The description of the optional feature, to be presented to the user. Defaults to the feature name, if not provided.

  • -always_recommend

    If set with a true value, the prerequisites are added to the distribution's metadata as recommended prerequisites (e.g. cpanminus will install recommendations with --with-recommends, even when running non-interactively).

    Defaults to false, but I recommend you turn this on.

  • -require_develop

    If set with a true value, the prerequisites are added to the distribution's metadata as develop requires prerequisites (e.g. cpanminus will install recommendations with --with-develop, even when running non-interactively).

    Defaults to true.

  • -prompt

    (Available since version 0.017)

    If set with a true value, Makefile.PL is modified to include interactive prompts.

    Default is true if -relationship is requires. false otherwise.

  • -load_prereqs

    (Available since version 0.021)

    If set, and -prompt is also set, the prerequisites to be added by the feature are checked for in the Perl installation; if the requirements are already met, then the feature is automatically added.

    Default is true.

  • -default

    (Available since version 0.006)

    If set with a true value, non-interactive installs will automatically fold the feature's prerequisites into the regular prerequisites.

    Note that at the time of this feature's creation (September 2013), there is no compliant CPAN client yet, as it invents a new x_default field in metadata under optional_feature (thanks, miyagawa!)

  • -phase

    The phase of the prequisite(s). Should be one of: build, test, runtime, or develop.

    Default: runtime

  • -relationship (or -type)

    The relationship of the prequisite(s). Should be one of: requires, recommends, suggests, or conflicts.

    Default: requires

SUPPORT

Bugs may be submitted through the RT bug tracker (or bug-Dist-Zilla-Plugin-OptionalFeature@rt.cpan.org). I am also usually active on irc, as 'ether' at irc.perl.org.

SEE ALSO

AUTHOR

Karen Etheridge <ether@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2013 by Karen Etheridge.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

CONTRIBUTOR

Kent Fredric <kentnl@cpan.org>

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