Added :prefix option to Module#delegate.

Signed-off-by: Michael Koziarski <michael@koziarski.com>

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

@@ -53,9 +53,11 @@ class Module
       raise ArgumentError, "Delegation needs a target. Supply an options hash with a :to key as the last argument (e.g. delegate :hello, :to => :greeter)."
     end
 
+    prefix = options[:prefix] ? "#{to}_" : ""
+
     methods.each do |method|
       module_eval(<<-EOS, "(__DELEGATION__)", 1)
-        def #{method}(*args, &block)
+        def #{prefix}#{method}(*args, &block)
           #{to}.__send__(#{method.inspect}, *args, &block)
         end
       EOS

activesupport/test/core_ext/module_test.rb

@@ -36,6 +36,10 @@ Someone   = Struct.new(:name, :place) do
   delegate :upcase, :to => "place.city"
 end
 
+Invoice   = Struct.new(:client) do
+  delegate :street, :city, :name, :to => :client, :prefix => true
+end
+
 class Name
   delegate :upcase, :to => :@full_name
 
@@ -85,6 +89,14 @@ class ModuleTest < Test::Unit::TestCase
     assert_raises(ArgumentError) { eval($noplace) }
   end
 
+  def test_delegation_prefix
+    david = Someone.new("David", Somewhere.new("Paulina", "Chicago"))
+    invoice = Invoice.new(david)
+    assert_equal invoice.client_name, "David"
+    assert_equal invoice.client_street, "Paulina"
+    assert_equal invoice.client_city, "Chicago"
+  end
+
   def test_parent
     assert_equal Yz::Zy, Yz::Zy::Cd.parent
     assert_equal Yz, Yz::Zy.parent