Bring returning back to ease migration.

Author: josevalim

activesupport/lib/active_support/core_ext/object.rb

@@ -2,6 +2,7 @@
 require 'active_support/core_ext/object/blank'
 require 'active_support/core_ext/object/duplicable'
 require 'active_support/core_ext/object/try'
+require 'active_support/core_ext/object/returning'
 
 require 'active_support/core_ext/object/conversions'
 require 'active_support/core_ext/object/instance_variables'

activesupport/lib/active_support/core_ext/object/returning.rb

@@ -0,0 +1,43 @@
+class Object
+  # Returns +value+ after yielding +value+ to the block. This simplifies the
+  # process of constructing an object, performing work on the object, and then
+  # returning the object from a method. It is a Ruby-ized realization of the K
+  # combinator, courtesy of Mikael Brockman.
+  #
+  # ==== Examples
+  #
+  #  # Without returning
+  #  def foo
+  #    values = []
+  #    values << "bar"
+  #    values << "baz"
+  #    return values
+  #  end
+  #
+  #  foo # => ['bar', 'baz']
+  #
+  #  # returning with a local variable
+  #  def foo
+  #    returning values = [] do
+  #      values << 'bar'
+  #      values << 'baz'
+  #    end
+  #  end
+  #
+  #  foo # => ['bar', 'baz']
+  #  
+  #  # returning with a block argument
+  #  def foo
+  #    returning [] do |values|
+  #      values << 'bar'
+  #      values << 'baz'
+  #    end
+  #  end
+  #  
+  #  foo # => ['bar', 'baz']
+  def returning(value)
+    ActiveSupport::Deprecation.warn('Object#returning has been deprecated in favor of Object#tap.', caller)
+    yield(value)
+    value
+  end
+end