Add MethodOverridingInitializer extension

1 files changed, 43 insertions, 11 deletions

diff --git a/lib/hashie/extensions/method_access.rb b/lib/hashie/extensions/method_access.rb
index e1ad56a..cf13da0 100644
--- a/lib/hashie/extensions/method_access.rb
+++ b/lib/hashie/extensions/method_access.rb
@@ -154,6 +154,22 @@ module Hashie
       end
     end
 
+    # A module shared between MethodOverridingWriter and MethodOverridingInitializer
+    # to contained shared logic. This module aids in redefining existing hash methods.
+    module RedefineMethod
+      protected
+
+      def method?(name)
+        methods.map(&:to_s).include?(name)
+      end
+
+      def redefine_method(method_name)
+        eigenclass = class << self; self; end
+        eigenclass.__send__(:alias_method, "__#{method_name}", method_name)
+        eigenclass.__send__(:define_method, method_name, -> { self[method_name] })
+      end
+    end
+
     # MethodOverridingWriter gives you #key_name= shortcuts for
     # writing to your hash. It allows methods to be overridden by
     # #key_name= shortcuts and aliases those methods with two
@@ -179,6 +195,8 @@ module Hashie
     #   h.__zip # => [[['awesome', 'sauce'], ['zip', 'a-dee-doo-dah']]]
     #
     module MethodOverridingWriter
+      include RedefineMethod
+
       def convert_key(key)
         key.to_s
       end
@@ -203,16 +221,6 @@ module Hashie
       def already_overridden?(name)
         method?("__#{name}")
       end
-
-      def method?(name)
-        methods.map(&:to_s).include?(name)
-      end
-
-      def redefine_method(method_name)
-        eigenclass = class << self; self; end
-        eigenclass.__send__(:alias_method, "__#{method_name}", method_name)
-        eigenclass.__send__(:define_method, method_name, -> { self[method_name] })
-      end
     end
 
     # A macro module that will automatically include MethodReader,
@@ -223,10 +231,34 @@ module Hashie
     # underscores.
     module MethodAccessWithOverride
       def self.included(base)
-        [MethodReader, MethodOverridingWriter, MethodQuery].each do |mod|
+        [MethodReader, MethodOverridingWriter, MethodQuery, MethodOverridingInitializer].each do |mod|
           base.send :include, mod
         end
       end
     end
+
+    # MethodOverridingInitializer allows you to override default hash
+    # methods when passing in values from an existing hash. The overriden
+    # methods are aliased with two leading underscores.
+    #
+    # @example
+    #   class MyHash < Hash
+    #     include Hashie::Extensions::MethodOverridingInitializer
+    #   end
+    #
+    #   h = MyHash.new(zip: 'a-dee-doo-dah')
+    #   h.zip # => 'a-dee-doo-dah'
+    #   h.__zip # => [[['zip', 'a-dee-doo-dah']]]
+    module MethodOverridingInitializer
+      include RedefineMethod
+
+      def initialize(hash = {})
+        hash.each do |key, value|
+          skey = key.to_s
+          redefine_method(skey) if method?(skey)
+          self[skey] = value
+        end
+      end
+    end
   end
 end