Added Hash#except which is the inverse of Hash#slice -- return the hash except the keys that are specified [DHH]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@7172 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

2 files changed, 26 insertions, 1 deletions

diff --git a/activesupport/lib/active_support/core_ext/hash.rb b/activesupport/lib/active_support/core_ext/hash.rb
index 2a99468b4e..b805d2da62 100644
--- a/activesupport/lib/active_support/core_ext/hash.rb
+++ b/activesupport/lib/active_support/core_ext/hash.rb
@@ -1,4 +1,4 @@
-%w(keys indifferent_access reverse_merge conversions diff slice).each do |ext|
+%w(keys indifferent_access reverse_merge conversions diff slice except).each do |ext|
   require "#{File.dirname(__FILE__)}/hash/#{ext}"
 end
 
@@ -9,4 +9,5 @@ class Hash #:nodoc:
   include ActiveSupport::CoreExtensions::Hash::Conversions
   include ActiveSupport::CoreExtensions::Hash::Diff
   include ActiveSupport::CoreExtensions::Hash::Slice
+  include ActiveSupport::CoreExtensions::Hash::Except
 end
diff --git a/activesupport/lib/active_support/core_ext/hash/except.rb b/activesupport/lib/active_support/core_ext/hash/except.rb
new file mode 100644
index 0000000000..8362cd880e
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/hash/except.rb
@@ -0,0 +1,24 @@
+require 'set'
+
+module ActiveSupport #:nodoc:
+  module CoreExtensions #:nodoc:
+    module Hash #:nodoc:
+      # Return a hash that includes everything but the given keys. This is useful for
+      # limiting a set of parameters to everything but a few known toggles:
+      #
+      #   @person.update_attributes(params[:person].except(:admin))
+      module Except
+        # Returns a new hash without the given keys.
+        def except(*keys)
+          rejected = Set.new(respond_to?(:convert_key) ? keys.map { |key| convert_key(key) } : keys)
+          reject { |key,| rejected.include?(key) }
+        end
+
+        # Replaces the hash without only the given keys.
+        def except!(*keys)
+          replace(except(*keys))
+        end
+      end
+    end
+  end
+end