require 'tsort' module Rails module Initializable def self.included(base) base.extend ClassMethods end class Initializer attr_reader :name, :block def initialize(name, context, options, &block) options[:group] ||= :default @name, @context, @options, @block = name, context, options, block end def before @options[:before] end def after @options[:after] end def belongs_to?(group) @options[:group] == group || @options[:group] == :all end def run(*args) @context.instance_exec(*args, &block) end def bind(context) return self if @context Initializer.new(@name, context, @options, &block) end end class Collection < Array include TSort alias :tsort_each_node :each def tsort_each_child(initializer, &block) select { |i| i.before == initializer.name || i.name == initializer.after }.each(&block) end def +(other) Collection.new(to_a + other.to_a) end end def run_initializers(group=:default, *args) return if instance_variable_defined?(:@ran) initializers.tsort_each do |initializer| initializer.run(*args) if initializer.belongs_to?(group) end @ran = true end def initializers @initializers ||= self.class.initializers_for(self) end module ClassMethods def initializers @initializers ||= Collection.new end def initializers_chain initializers = Collection.new ancestors.reverse_each do |klass| next unless klass.respond_to?(:initializers) initializers = initializers + klass.initializers end initializers end def initializers_for(binding) Collection.new(initializers_chain.map { |i| i.bind(binding) }) end def initializer(name, opts = {}, &blk) raise ArgumentError, "A block must be passed when defining an initializer" unless blk opts[:after] ||= initializers.last.name unless initializers.empty? || initializers.find { |i| i.name == opts[:before] } initializers << Initializer.new(name, nil, opts, &blk) end end end end