Add #replace to Hashie::Mash to achieve Hash-like behavior

2 files changed, 28 insertions, 0 deletions

diff --git a/lib/hashie/mash.rb b/lib/hashie/mash.rb
index 4d25b3b..04d6980 100644
--- a/lib/hashie/mash.rb
+++ b/lib/hashie/mash.rb
@@ -175,6 +175,11 @@ module Hashie
       self
     end
 
+    def replace(other_hash)
+      (keys - other_hash.keys).each { |key| delete(key) }
+      other_hash.each { |key, value| self[key] = value }
+    end
+
    # Will return true if the Mash has had a key
    # set in addition to normal respond_to? functionality.
    def respond_to?(method_name, include_private=false)
diff --git a/spec/hashie/mash_spec.rb b/spec/hashie/mash_spec.rb
index 6cd3994..78e0223 100644
--- a/spec/hashie/mash_spec.rb
+++ b/spec/hashie/mash_spec.rb
@@ -183,6 +183,29 @@ describe Hashie::Mash do
       end
     end
 
+    describe '#replace' do
+      before do
+        subject.replace(:middle_name => "Cain",
+          :details => {:city => "Imagination"})
+      end
+
+      it 'sets all specified keys to their corresponding values' do
+        subject.middle_name?.should be_true
+        subject.details?.should be_true
+        subject.middle_name.should == "Cain"
+        subject.details.city?.should be_true
+        subject.details.city.should == "Imagination"
+      end
+
+      it 'leaves only specified keys' do
+        subject.keys.should == ['middle_name', 'details']
+        subject.first_name?.should be_false
+        subject.first_name.should be_nil
+        subject.last_name?.should be_false
+        subject.last_name.should be_nil
+      end
+    end
+
     describe 'delete' do
       it 'should delete with String key' do
         subject.delete('details')