module Rails module Initializable def self.included(base) base.extend ClassMethods end class Initializer attr_reader :name, :block def initialize(name, context, options, &block) @name, @context, @options, @block = name, context, options, block end def before @options[:before] end def after @options[:after] 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 def initialize(initializers = []) super() initializers.each do |initializer| if initializer.before index = index_for(initializer.before) elsif initializer.after index = index_for(initializer.after) index += 1 if index else index = length end insert(index || -1, initializer) end end def +(other) Collection.new(to_a + other.to_a) end def index_for(name) initializer = find { |i| i.name == name } initializer && index(initializer) end end def run_initializers(*args) return if instance_variable_defined?(:@ran) initializers.each do |initializer| initializer.run(*args) end @ran = true end def initializers @initializers ||= self.class.initializers_for(self) end module ClassMethods def initializers @initializers ||= [] 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 initializers << Initializer.new(name, nil, opts, &blk) end def run_initializers(*args) return if @ran initializers_chain.each do |initializer| instance_exec(*args, &initializer.block) end @ran = true end end end end