require 'sham' module Machinist # A Lathe is used to execute the blueprint and construct an object. # # The blueprint is instance_eval'd against the Lathe. class Lathe def self.run(adapter, object, *args) blueprint = object.class.blueprint named_blueprint = object.class.blueprint(args.shift) if args.first.is_a?(Symbol) attributes = args.pop || {} raise "No blueprint for class #{object.class}" if blueprint.nil? lathe = self.new(adapter, object, attributes) lathe.instance_eval(&named_blueprint) if named_blueprint klass = object.class while klass lathe.instance_eval(&klass.blueprint) if klass.respond_to?(:blueprint) && klass.blueprint klass = klass.superclass end lathe end def initialize(adapter, object, attributes = {}) @adapter = adapter @object = object attributes.each {|key, value| assign_attribute(key, value) } end def object yield @object if block_given? @object end def method_missing(symbol, *args, &block) if attribute_assigned?(symbol) # If we've already assigned the attribute, return that. @object.send(symbol) elsif @adapter.has_association?(@object, symbol) && !@object.send(symbol).nil? # If the attribute is an association and is already assigned, return that. @object.send(symbol) else # Otherwise generate a value and assign it. assign_attribute(symbol, generate_attribute_value(symbol, *args, &block)) end end def assigned_attributes @assigned_attributes ||= {} end # Undef a couple of methods that are common ActiveRecord attributes. # (Both of these are deprecated in Ruby 1.8 anyway.) undef_method :id if respond_to?(:id) undef_method :type if respond_to?(:type) private def assign_attribute(key, value) assigned_attributes[key.to_sym] = value @object.send("#{key}=", value) end def attribute_assigned?(key) assigned_attributes.has_key?(key.to_sym) end def generate_attribute_value(attribute, *args) if block_given? # If we've got a block, use that to generate the value. yield else # Otherwise, look for an association or a sham. if @adapter.has_association?(object, attribute) @adapter.class_for_association(object, attribute).make(args.first || {}) elsif args.empty? Sham.send(attribute) else # If we've got a constant, just use that. args.first end end end end # This sets a flag that stops make from saving objects, so # that calls to make from within a blueprint don't create # anything inside make_unsaved. def self.with_save_nerfed begin @@nerfed = true yield ensure @@nerfed = false end end @@nerfed = false def self.nerfed? @@nerfed end end