Made the :prefix option on Module#delegate accept a custom prefix.

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

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

@@ -53,7 +53,7 @@ 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}_" : ""
+    prefix = options[:prefix] && (options[:prefix] == true ? "#{to}_" : "#{options[:prefix]}_")
 
     methods.each do |method|
       module_eval(<<-EOS, "(__DELEGATION__)", 1)

activesupport/test/core_ext/module_test.rb

@@ -38,6 +38,7 @@ end
 
 Invoice   = Struct.new(:client) do
   delegate :street, :city, :name, :to => :client, :prefix => true
+  delegate :street, :city, :name, :to => :client, :prefix => :customer
 end
 
 class Name
@@ -97,6 +98,14 @@ class ModuleTest < Test::Unit::TestCase
     assert_equal invoice.client_city, "Chicago"
   end
 
+  def test_delegation_custom_prefix
+    david = Someone.new("David", Somewhere.new("Paulina", "Chicago"))
+    invoice = Invoice.new(david)
+    assert_equal invoice.customer_name, "David"
+    assert_equal invoice.customer_street, "Paulina"
+    assert_equal invoice.customer_city, "Chicago"
+  end
+
   def test_parent
     assert_equal Yz::Zy, Yz::Zy::Cd.parent
     assert_equal Yz, Yz::Zy.parent