NAME
Plugin::Tiny - A tiny plugin system for perl
VERSION
version 0.005
SYNOPSIS
#in your core
use Plugin::Tiny;
my $ps=Plugin::Tiny->new(); #plugin system
#load plugin_class (and perhaps phase) from your configuration
$ps->register(
phase=>$phase, #optional; defaults to last part of plugin class
plugin=>$plugin_class, #required
role=>$role, #optional
arg1=>$arg1, #optional
arg2=>$arg2, #optional
);
#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.
Your Plugins
Plugin::Tiny requires that your plugins are objects (a package with new). Plugin::Tiny uses Moose internally, but this being perl you are of course free to use whatever object system you like:
package My::Plugin; #a complete plugin that doesn't do very much
use Moose;
sub do_something {
print "Hello World\n";
}
1;Recommendation: First Register Then Do Things
Plugin::Tiny suggests that you first load all your plugins (during the register) before you actually do something with them. Internal require/use of your packages is deferred to runtime. You can control 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 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 hand the plugin system down to the (bundleing) plugin. That way, you can load multiple plugins for one phase. You still need unique phases for each plugin:
package My::Core;
use Moose; #optional
has 'plugins'=>(
is=>'ro',
isa=>'Plugin::Tiny',
default=>sub{Plugin::Tiny->new},
);
$self->plugins->register(
phase=>'Scan',
plugin=>'PluginBundle',
plugins=>$self->plugins, #plugin system
);
package PluginBundle;
has 'plugins'=>(is=>'ro', isa=>'Plugin::Tiny', required=>1);
#phase defaults to 'One' and 'Two'
$self->plugins->register_bundle({Plugin::One=>{},Plugin::Two=>{}});
#more or less the same as:
$self->plugins->register (plugin=>'Plugin::One');
$self->plugins->register (plugin=>'Plugin::Two');
my $one=$self->plugins->get('One');
$one->do_something(@args); ATTRIBUTES
debug
expects a boolean. Prints additional info to STDOUT.
prefix
Optional init argument. 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 init argument. A default role to be applied to all plugins. Can be overwritten in register.
METHODS
register
Registers a plugin, e.g. uses it and makes a new plugin object. Needs a plugin. If you don't specify a phase it, it uses a default phase from the plugin class name. See method default_phae for details.
$ps->register(phase=>$phase, plugin=>$plugin_class); Optionally, you can also specify a role which your plugin will have to be able to apply. Specify role=>undef to unset global roles.
Remaining key value pairs are passed down to the plugin constructor:
$plugin_system->register (
plugin=>$plugin_class, #required
phase=>$phase, #optional
role=>$role, #optional
plugins=>$plugin_system, #optional
args=>$more_args, #optional
);A side-effect is that your plugin cannot use 'phase', 'plugin', 'role' as named arguments.
Returns the newly created plugin object on success. Confesses on error.
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 extending your plugins perhaps you put them the hashref in a separate sub, so you can extend it or remove plugins in a child bundle.
get_plugin
Returns the plugin object associated with the phase. Returns undef on failure.
$plugin=$ps->get_plugin ($phase);default_phase
Makes a default phase from a class name. Expects a $plugin_class. If prefix is defined it use tail and removes remaining '::'. Without prefix default is just the last element of the class name:
$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'Returns scalar or undef.
get_class
returns the plugin's class. A bit like ref $plugin. Not sure what it returns on error. Todo!
$class=$ps->get_class ($plugin);get_phase
returns the plugin's phase. Returns undef on failure. Normally, you should not need this: $phase=$ps->get_phase ($plugin);
AUTHOR
Maurice Mengel <mauricemengel@gmail.com>
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.