@@ -1,5 +1,7 @@ *2.3.0 [Edge]* +* Add :allow_nil option to delegate. #1127 [Sergio Gil] + * Add Benchmark.ms convenience method to benchmark realtime in milliseconds. [Jeremy Kemper] * Updated included memcache-client to the 1.5.0.5 version which includes fixes from fiveruns and 37signals to deal with failover and timeouts #1535 [Joshua Sierles] activesupport/CHANGELOG @@ -72,6 +72,30 @@ class Module # invoice.customer_name # => "John Doe" # invoice.customer_address # => "Vimmersvej 13" # + # If the object to which you delegate can be nil, you may want to use the + # :allow_nil option. In that case, it returns nil instead of raising a + # NoMethodError exception: + # + # class Foo + # attr_accessor :bar + # def initialize(bar = nil) + # @bar = bar + # end + # delegate :zoo, :to => :bar + # end + # + # Foo.new.zoo # raises NoMethodError exception (you called nil.zoo) + # + # class Foo + # attr_accessor :bar + # def initialize(bar = nil) + # @bar = bar + # end + # delegate :zoo, :to => :bar, :allow_nil => true + # end + # + # Foo.new.zoo # returns nil + # def delegate(*methods) options = methods.pop unless options.is_a?(Hash) && to = options[:to] @@ -84,10 +108,12 @@ class Module prefix = options[:prefix] && "#{options[:prefix] == true ? to : options[:prefix]}_" + allow_nil = options[:allow_nil] && "#{to} && " + methods.each do |method| module_eval(<<-EOS, "(__DELEGATION__)", 1) def #{prefix}#{method}(*args, &block) - #{to}.__send__(#{method.inspect}, *args, &block) + #{allow_nil}#{to}.__send__(#{method.inspect}, *args, &block) end EOS end activesupport/lib/active_support/core_ext/module/delegation.rb @@ -41,6 +41,10 @@ Invoice = Struct.new(:client) do delegate :street, :city, :name, :to => :client, :prefix => :customer end +Project = Struct.new(:description, :person) do + delegate :name, :to => :person, :allow_nil => true +end + class Name delegate :upcase, :to => :@full_name @@ -117,6 +121,29 @@ class ModuleTest < Test::Unit::TestCase end end + def test_delegation_with_allow_nil + rails = Project.new("Rails", Someone.new("David")) + assert_equal rails.name, "David" + end + + def test_delegation_with_allow_nil_and_nil_value + rails = Project.new("Rails") + assert_nil rails.name + end + + def test_delegation_with_allow_nil_and_nil_value_and_prefix + Project.class_eval do + delegate :name, :to => :person, :allow_nil => true, :prefix => true + end + rails = Project.new("Rails") + assert_nil rails.person_name + end + + def test_delegation_without_allow_nil_and_nil_value + david = Someone.new("David") + assert_raises(NoMethodError) { david.street } + end + def test_parent assert_equal Yz::Zy, Yz::Zy::Cd.parent assert_equal Yz, Yz::Zy.parent activesupport/test/core_ext/module_test.rb f7bd0beb67c5d9d50e37aa596605b91e61197fbe Sergio Gil porras sgilperez@gmail.com http://github.com/rails/rails/commit/e8de7a67a5ef063164da022845a7cae1753da80e e8de7a67a5ef063164da022845a7cae1753da80e 2008-12-21T15:24:06-08:00 2008-12-07T15:53:38-08:00 Add :allow_nil option to delegate [#1127 state:resolved] Signed-off-by: Pratik Naik <pratiknaik@gmail.com> 6b9f49120dd9f95b4b5800454520bf1cc4dcf793 Pratik Naik lifo pratiknaik@gmail.com