Merge pull request rails#50302 from Shopify/delegate-as-opt

Module#delegate takes a new private `as` parameter

Author: byroot

actioncable/lib/action_cable/channel/broadcasting.rb

@@ -7,10 +7,6 @@ module Channel
     module Broadcasting
       extend ActiveSupport::Concern
 
-      included do
-        delegate :broadcasting_for, :broadcast_to, to: :class
-      end
-
       module ClassMethods
         # Broadcast a hash to a unique broadcasting for this <tt>model</tt> in this channel.
         def broadcast_to(model, message)
@@ -38,6 +34,8 @@ def serialize_broadcasting(object) # :nodoc:
           end
         end
       end
+
+      delegate :broadcasting_for, :broadcast_to, to: :class, as: ClassMethods
     end
   end
 end

actioncable/lib/action_cable/channel/naming.rb

@@ -18,10 +18,7 @@ def channel_name
         end
       end
 
-      included do
-        # Delegates to the class's ::channel_name.
-        delegate :channel_name, to: :class
-      end
+      delegate :channel_name, to: :class, as: ClassMethods
     end
   end
 end

actionview/lib/action_view/layouts.rb

@@ -209,11 +209,9 @@ module Layouts
 
     included do
       class_attribute :_layout, instance_accessor: false
-      class_attribute :_layout_conditions, instance_accessor: false, default: {}
+      class_attribute :_layout_conditions, instance_accessor: false, instance_reader: true, default: {}
 
       _write_layout_method
-
-      delegate :_layout_conditions, to: :class
     end
 
     module ClassMethods

activesupport/lib/active_support/core_ext/module/delegation.rb

@@ -168,7 +168,7 @@ class DelegationError < NoMethodError; end
   #   Foo.new("Bar").name # raises NoMethodError: undefined method `name'
   #
   # The target method must be public, otherwise it will raise +NoMethodError+.
-  def delegate(*methods, to: nil, prefix: nil, allow_nil: nil, private: nil)
+  def delegate(*methods, to: nil, prefix: nil, allow_nil: nil, private: nil, as: nil)
     unless to
       raise ArgumentError, "Delegation needs a target. Supply a keyword argument 'to' (e.g. delegate :hello, to: :greeter)."
     end
@@ -190,6 +190,16 @@ def delegate(*methods, to: nil, prefix: nil, allow_nil: nil, private: nil)
     receiver = to.to_s
     receiver = "self.#{receiver}" if DELEGATION_RESERVED_METHOD_NAMES.include?(receiver)
 
+    explicit_receiver = false
+    receiver_class = if as
+      explicit_receiver = true
+      as
+    elsif to.is_a?(Module)
+      to.singleton_class
+    elsif receiver == "self.class"
+      singleton_class
+    end
+
     method_def = []
     method_names = []
 
@@ -205,16 +215,14 @@ def delegate(*methods, to: nil, prefix: nil, allow_nil: nil, private: nil)
         if /[^\]]=\z/.match?(method)
           "arg"
         else
-          method_object =
+          method_object = if receiver_class
             begin
-              if to.is_a?(Module)
-                to.method(method)
-              elsif receiver == "self.class"
-                method(method)
-              end
+              receiver_class.public_instance_method(method)
             rescue NameError
+              raise if explicit_receiver
               # Do nothing. Fall back to `"..."`
             end
+          end
 
           if method_object
             parameters = method_object.parameters

activesupport/test/core_ext/module_test.rb

@@ -586,14 +586,25 @@ def initialize(place)
       location.delegate(:street, :city, to: :@place, prefix: :the, private: true)
   end
 
-  def test_delegation_arity
+  def test_delegation_arity_to_module
     c = Class.new do
       delegate :zero, :one, :two, to: ArityTester
     end
     assert_equal 0, c.instance_method(:zero).arity
     assert_equal 1, c.instance_method(:one).arity
     assert_equal 2, c.instance_method(:two).arity
 
+    e = Class.new do
+      delegate :zero, to: ArityTesterModule
+    end
+
+    assert_equal 0, e.instance_method(:zero).arity
+    assert_nothing_raised do
+      e.new.zero
+    end
+  end
+
+  def test_delegation_arity_to_self_class
     d = Class.new(ArityTester) do
       delegate :zero, :zero_with_block, :zero_with_implicit_block, :one, :one_with_block, :two, :opt,
         :kwargs, :kwargs_with_block, :opt_kwargs, :opt_kwargs_with_block, to: :class
@@ -623,14 +634,5 @@ def test_delegation_arity
       d.new.opt_kwargs(a: 1)
       d.new.opt_kwargs_with_block(a: 1, b: 2, c: 3)
     end
-
-    e = Class.new do
-      delegate :zero, to: ArityTesterModule
-    end
-
-    assert_equal 0, e.instance_method(:zero).arity
-    assert_nothing_raised do
-      e.new.zero
-    end
   end
 end