NAME Plugin::Tiny - A tiny plugin system for perl VERSION version 0.012 SYNOPSIS #a complete 'Hello World' plugin package My::Plugin; use Moose; #optional; required is an object with new as constructor sub do_something { print "Hello World @_\n" } 1; #in your core use Plugin::Tiny; my $ps=Plugin::Tiny->new(); #plugin system #load My::Plugin: require, import, return My::Plugin->new(@_) my $plugin=$ps->register(plugin=>'My::Plugin'); #elsewhere in core: execute your plugin's methods my $plugin=$ps->get_plugin ($phase); $plugin->do_something(@args); DESCRIPTION Plugin::Tiny is minimalistic plugin system for perl. Each plugin is associated with a keyword (referred to as phase). A limitation of Plugin::Tiny is that each phase can have only one plugin. Plugin::Tiny calls itself tiny because it doesn't attempt to solve all problems plugin systems could solve, because it consists of one smallish package, and it doesn't depend on a whole lot. ATTRIBUTES debug Optional. Expects a boolean. Prints additional info to STDOUT. prefix Optional. You can have the prefix added to all plugin classes you register so save some typing and force plugins in your namespace: #without prefix my $ps=Plugin::Tiny->new $ps->register(plugin='Your::App::Plugin::Example1'); $ps->register(plugin='Your::App::Plugin::Example2'); #with prefix my $ps=Plugin::Tiny->new ( prefix=>'Your::App::Plugin::' ); $ps->register(plugin='Example1'); $ps->register(plugin='Example2'); role Optional. One or more roles that all plugins have to be able to do. Can be overwritten in "register". role=>['Role::One', Role::Two] #either as ArrayRef role=>'Role::One' #or a scalar METHODS register Registers a plugin, i.e. loads it and makes a new plugin object. Needs a plugin package name (plugin). Returns the newly created plugin object on success. Confesses on error. Remaining arguments are passed down to the plugin constructor: $obj=$ps->register( plugin=>$plugin_class, #required args=>$more_args, #optional ); #returns result of $plugin_class->new (args=>$args); N.B. Your plugin cannot use 'phase', 'plugin', 'role', 'force' as named arguments. plugin The package name of the plugin. Required. Internally, the value of "prefix" is prepended to plugin. phase A phase asociated with the plugin. Optional. If not specified, Plugin::Tiny uses "default_phase" to determine the phase. role One or more roles that the plugin has to appply. Optional. Specify role=>undef to unset global roles. Currently, you can't mix global roles (defined via new) with local roles (defined via register). role=>'Single::Role' #or role=>['Role::One','Role:Two'] role=>undef #unset global roles force Force re-registration of a previously used phase. Optional. Normally, Plugin::Tiny confesses if you try to register a phase that has previously been assigned. To overwrite this message make force true. With force both plugins will be loaded (required, imported) and both return new objects for their respective plugin classes, but after the second plugin is made, the first one cannot be accessed anymore through get_plugin. register_bundle Registers a bundle of plugins in no particular order. A bundle is just a hashRef with info needed to issue a series of register calls (see "register"). Confesses if a plugin cannot be registered. Otherwise returns $bundle or undef. sub bundle{ return { 'Store::One' => { phase => 'Store', role => undef, dbfile => $self->core->config->{main}{dbfile}, }, 'Scan::Monitor'=> { core => $self->core }, }; } $ps->register_bundle(bundle) If you want to add or remove plugins, use hashref as usual: undef $bundle->{$plugin}; #remove a plugin using package name $bundle->{'My::Plugin'}={phase=>'foo'}; #add another plugin To facilitate inheritance of your plugins perhaps you put the hashref in a separate sub, so a child bundle can extend or remove plugins from yours. get_plugin Returns the plugin object associated with the phase. Returns undef on failure. my $plugin=$ps->get_plugin ($phase); default_phase Makes a default phase from (the plugin's) class name. Expects a $plugin_class. Returns scalar or undef. If prefix is defined it use tail and removes all '::'. If no prefix is set default_phase returns the last element of the class name: my $ps=Plugin-Tiny->new; $ps->default_phase(My::Plugin::Long::Example); #returns 'Example' $ps=Plugin-Tiny->new(prefix=>'My::Plugin::'); $ps->default_phase(My::Plugin::Long::Example); #returns 'LongExample' get_class Returns the plugin's class (package name). Expects plugin (not its package name). Croaks on error. my $class=$ps->get_class ($plugin); get_phase returns the plugin's phase. Expects plugin (not its package name). Returns undef on failure. (You will not normally need get_phase, because typically your code knows the phases.) my $phase=$ps->get_phase ($plugin); Recommendation: First Register Then Do Things Plugin::Tiny suggests that you first register (load) all your plugins before you actually do something with them. Internal "require" / "use" of your packages is deferred until runtime. You can control the order in which plugins are loaded (in the order you call "register"), but if you manage to load all of them before you do anything, you can forget about order. You may know Plugin::Tiny's phases at compile time, but not which plugins will be loaded. Recommendation: Require a Plugin Role You may want to do a plugin role for all you plugins, e.g. to standardize the interface for your plugins. Perhaps to make sure that a specific sub is available in the plugin: package My::Plugin; use Moose; with 'Your::App::Role::Plugin'; #... Plugin Bundles You can create bundles of plugins if you pass the plugin system to the (bundling) plugin. That way you can load multiple plugins for one phase. You still need unique phases for each plugin: package My::Core; use Moose; has 'plugin_system'=>( is=>'ro', isa=>'Plugin::Tiny', default=>sub{Plugin::Tiny->new}, ); sub BUILD { $self->plugins->register( plugin=>'PluginBundle', phase=>'Bundle', plugin_system=>$self->plugins, ); } #elsewhere in core my $b=$self->plugin_system->get_plugin ('Bundle'); $b->start(); package PluginBundle; use Moose; has 'plugin_system'=>(is=>'ro', isa=>'Plugin::Tiny', required=>1); sub bundle { {Plugin::One=>{},Plugin::Two=>{}} } sub BUILD { #phase defaults to 'One' and 'Two': $self->plugins->register_bundle(bundle()); #more or less the same as: #$self->plugins->register (plugin=>'Plugin::One'); #$self->plugins->register (plugin=>'Plugin::Two'); } sub start { my $one=$self->plugins->get('One'); $one->do_something(@args); } CONTRIBUTORS Thanks to Toby Inkster for making Plugin::Tiny tinier. SEE ALSO Object::Pluggable Module::Pluggable MooX::Role::Pluggable MooseX::Object::Pluggable MooseX::Role::Pluggable AUTHOR Maurice Mengel COPYRIGHT AND LICENSE This software is copyright (c) 2012 by Maurice Mengel. This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.