Introduce Array.wrap(foo) to wrap the argument in an array unless it's already an array. Wraps nil as an empty array. Use instead of Array(foo) and foo.to_a since they treat String as Enumerable.

activesupport/CHANGELOG

@@ -1,3 +1,8 @@
+*Edge*
+
+* Introduce Array.wrap(foo) to wrap the argument in an array unless it's already an array. Wraps nil as an empty array. Use instead of Array(foo) and foo.to_a since they treat String as Enumerable.  [Jeremy Kemper]
+
+
 *2.3.0 [RC1] (February 1st, 2009)*
 
 * TimeWithZone#xmlschema accepts optional fraction_digits argument [#1725 state:resolved] [Nicholas Dainty]

activesupport/lib/active_support/core_ext/array.rb

@@ -3,6 +3,7 @@
 require 'active_support/core_ext/array/extract_options'
 require 'active_support/core_ext/array/grouping'
 require 'active_support/core_ext/array/random_access'
+require 'active_support/core_ext/array/wrapper'
 
 class Array #:nodoc:
   include ActiveSupport::CoreExtensions::Array::Access
@@ -10,4 +11,5 @@ class Array #:nodoc:
   include ActiveSupport::CoreExtensions::Array::ExtractOptions
   include ActiveSupport::CoreExtensions::Array::Grouping
   include ActiveSupport::CoreExtensions::Array::RandomAccess
+  extend ActiveSupport::CoreExtensions::Array::Wrapper
 end

activesupport/lib/active_support/core_ext/array/wrapper.rb

@@ -0,0 +1,19 @@
+module ActiveSupport #:nodoc:
+  module CoreExtensions #:nodoc:
+    module Array #:nodoc:
+      module Wrapper
+        # Wraps the object in an Array unless it's an Array.
+        def wrap(object)
+          case object
+          when nil
+            []
+          when self
+            object
+          else
+            [object]
+          end
+        end
+      end
+    end
+  end
+end

activesupport/test/core_ext/array_ext_test.rb

@@ -302,3 +302,27 @@ def test_random_element_from_array
     assert_equal 2, [1, 2, 3].rand
   end
 end
+
+class ArrayWrapperTests < Test::Unit::TestCase
+  def test_array
+    ary = %w(foo bar)
+    assert_same ary, Array.wrap(ary)
+  end
+
+  def test_nil
+    assert_equal [], Array.wrap(nil)
+  end
+
+  def test_object
+    o = Object.new
+    assert_equal [o], Array.wrap(o)
+  end
+
+  def test_string
+    assert_equal ["foo"], Array.wrap("foo")
+  end
+
+  def test_string_with_newline
+    assert_equal ["foo\nbar"], Array.wrap("foo\nbar")
+  end
+end