Added support for deferred properties to Dash

2 files changed, 22 insertions, 2 deletions

diff --git a/lib/hashie/dash.rb b/lib/hashie/dash.rb
index bdc256d..8a1f6f7 100644
--- a/lib/hashie/dash.rb
+++ b/lib/hashie/dash.rb
@@ -110,8 +110,13 @@ module Hashie
     def [](property)
       assert_property_exists! property
       value = super(property.to_s)
-      yield value if block_given?
-      value
+      # If the value is a lambda, proc, or whatever answers to call, eval the thing!
+      if value.is_a? Proc
+        self[property] = value.call # Set the result of the call as a value
+      else
+        yield value if block_given?
+        value
+      end
     end
 
     # Set a value on the Dash in a Hash-like way. Only works
diff --git a/spec/hashie/dash_spec.rb b/spec/hashie/dash_spec.rb
index 1267651..1e1edc9 100644
--- a/spec/hashie/dash_spec.rb
+++ b/spec/hashie/dash_spec.rb
@@ -26,6 +26,10 @@ class DashDefaultTest < Hashie::Dash
   property :aliases, :default => ["Snake"]
 end
 
+class DeferredTest < Hashie::Dash
+  property :created_at, :default => Proc.new { Time.now }
+end
+
 describe DashTest do
 
   subject { DashTest.new(:first_name => 'Bob', :email => 'bob@example.com') }
@@ -100,6 +104,17 @@ describe DashTest do
     end
   end
 
+  context 'reading from deferred properties' do
+    it 'should evaluate proc after initial read' do
+      DeferredTest.new['created_at'].should be_instance_of(Time)
+    end
+
+    it "should not evalute proc after subsequent reads" do
+      deferred = DeferredTest.new
+      deferred['created_at'].object_id.should == deferred['created_at'].object_id
+    end
+  end
+
   describe '.new' do
     it 'fails with non-existent properties' do
       lambda { described_class.new(:bork => '') }.should raise_error(NoMethodError)