@@ -36,11 +36,56 @@ It can also have callbacks when entering some state: puts "Confirmed" end +Adding MicroMachine to your models +---------------------------------- + +The most popular pattern among Ruby libraries that tackle this problem +is to extend the model and transform it into a finite state machine. +Instead of working as a mixin, MicroMachine's implementation is by +composition: you instantiate a finite state machine (or many!) inside +your model and you are in charge of querying and persisting the state. +Here's an example of how to use it with an ActiveRecord model: + + class Event < ActiveRecord::Base + before_save :persist_confirmation + + def confirm! + confirmation.trigger(:confirm) + end + + def cancel! + confirmation.trigger(:cancel) + end + + def reset! + confirmation.trigger(:reset) + end + + def confirmation + @confirmation ||= begin + @confirmation = MicroMachine.new(confirmation_state || "pending") + @confirmation.transitions_for[:confirm] = { "pending" => "confirmed" } + @confirmation.transitions_for[:cancel] = { "confirmed" => "cancelled" } + @confirmation.transitions_for[:reset] = { "confirmed" => "pending", "cancelled" => "pending" } + @confirmation + end + end + + private + + def persist_confirmation + self.confirmation_state = confirmation.state + end + end + +This example asumes you have a :confirmation_state attribute in your +model. This may look like a very verbose implementation, but you gain a +lot in flexibility. + Installation ------------ - $ gem sources -a http://gems.github.com (you only have to do this once) - $ sudo gem install soveran-micromachine + $ sudo gem install micromachine License ------- README.markdown @@ -9,7 +9,7 @@ Gem::Specification.new do |s| s.specification_version = 2 if s.respond_to? :specification_version= - s.files = <%= FileList['lib/**/*.rb', 'README*', 'LICENSE', 'Rakefile', 'example/**/*.*'].inspect %> + s.files = <%= Dir['lib/**/*.rb', 'README*', 'LICENSE', 'Rakefile', 'example/**/*.*'].inspect %> s.require_paths = ['lib'] micromachine.gemspec.erb 446f6cd03cb4989785cdaee39c3653b27db83dcf Michel Martens michel@soveran.com http://github.com/soveran/micromachine/commit/da6d94b739dfbe82f1e363f29617030ac181dcc0 da6d94b739dfbe82f1e363f29617030ac181dcc0 2009-06-06T17:40:47-07:00 2009-06-06T17:40:47-07:00 Updated documentation and gemspec 0f12d35d11f7c3c60b0ba81ebd4b47984b109824 Michel Martens michel@soveran.com