NAME
    Module::Patch - Patch package with a set of patches

VERSION
    version 0.14

SYNOPSIS
    To use Module::Patch directly:

     # patching DBI modules so that calls are logged

     use Module::Patch qw(patch_package);
     use Log::Any '$log';
     patch_package(['DBI', 'DBI::st', 'DBI::db'], [
         {action=>'wrap', mod_version=>':all', sub_name=>':public', code=>sub {
             my $ctx      = shift;
             my $orig_sub = shift;
             $log->tracef("Entering %s(%s) ...", $ctx->{orig_name}, \@_);
             my $res;
             if (wantarray) { $res=[$orig_sub->(@_)] } else { $res=$orig_sub->(@_) }
             $log->tracef("Returned from %s", $ctx->{orig_name});
             if (wantarray) { return @$res } else { return $res }
         }},
     ]);

    To create a patch module by subclassing Module::Patch:

     # in your patch module

     package Some::Module::Patch::YourCategory;
     use parent qw(Module::Patch);

     sub patch_data {
         return {
             v => 3,
             patches => [...], # $patches_spec
             config => { # per-patch-module config
                 a => {
                     default => 1,
                 },
                 b => {},
                 c => {
                     default => 3,
                 },
             },
         };
     }
     1;

     # using your patch module

     use Some::Module::Patch::YourCategory
         -force => 1, # optional, force patch even if target version does not match
         -config => {a=>10, b=>20}, # optional, set config value
     ;

     # accessing per-patch-module config data

     print $Some::Module::Patch::YourCategory::config->{a}; # 10
     print $Some::Module::Patch::YourCategory::config->{c}; # 3, default value

     # unpatch, restore original subroutines
     no Some::Module::Patch::YourCategory;

DESCRIPTION
    Module::Patch is basically a convenient way to define and bundle a set
    of patches. Actual patching is done by Monkey::Patch::Action, which
    provides lexically scoped patching.

    There are two ways to use this module:

    *   subclass it

        This is used for convenient bundling of patches. You create a *patch
        module* (a module that monkey-patches other module by
        adding/replacing/wrapping/deleting subroutines of target module) by
        subclassing Module::Patch and providing the patches_spec in
        patch_data() method.

        Patch module should be named *Some::Module*::Patch::*YourCategory*.
        *YourCategory* should be a keyword or phrase (verb + obj) that
        describes what the patch does. For example,
        HTTP::Daemon::Patch::IPv6, LWP::UserAgent::Patch::LogResponse.

    *   require/import it directly

        Module::Patch provides patch_package which is the actual routine to
        do the patching.

FUNCTIONS
  import()
    If imported directly, will export @exports as arguments and export
    requested symbols.

    If imported from subclass, will take %opts as arguments and run
    patch_package() on caller package. %opts include:

    *   -load_target => BOOL (default 1)

        Load target modules. Set to 0 if package is already defined in other
        files and cannot be require()-ed.

    *   -force => BOOL

        Will be passed to patch_package's \%opts.

  patch_package($package, $patches_spec, \%opts)
    Patch target package $package with a set of patches.

    $patches_spec is an arrayref containing a series of patch specification.
    Patch specification is a hashref containing these keys: "action"
    (string, required; either 'wrap', 'add', 'replace', 'add_or_replace',
    'delete'), "mod_version" (string/regex or array of string/regex, can be
    ':all' to mean all versions; optional; defaults to ':all'). "sub_name"
    (string/regex or array of string/regex, subroutine(s) to patch, can be
    ':all' to mean all subroutine, ':public' to mean all public subroutines
    [those not prefixed by "_"], ':private' to mean all private), "code"
    (coderef, not required if "action" is 'delete').

    Die if there is conflict with other patch modules (patchsets), for
    example if target module has been patched 'delete' and another patch
    wants to 'wrap' it.

    NOTE: conflict checking with other patchsets not yet implemented.

    Known options:

    *   force => BOOL (default 0)

        Force patching even if target module version does not match. The
        default is to warn and skip patching.

SEE ALSO
    Monkey::Patch::Action

    Pod::Weaver::Plugin::ModulePatch

    Some examples of patch modules that use Module::Patch by subclassing it:
    Net::HTTP::Methods::Patch::LogRequest,
    LWP::UserAgent::Patch::HTTPSHardTimeout.

    Some examples of modules that use Module::Patch directly:
    Log::Any::For::Class.

AUTHOR
    Steven Haryanto <stevenharyanto@gmail.com>

COPYRIGHT AND LICENSE
    This software is copyright (c) 2012 by Steven Haryanto.

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

