Added presenter#accepts?(sym) so you can query a presenter instance t…

…o see if presents on a particular symbol. Useful in Rails applications so controllers can always set the current_user on any presenter that accepts :current_user

History.txt

@@ -1,4 +1,8 @@
-== 0.9.0, February 14th, 2009
+== February 16th, 2009
+
+* Added ability to query a presenter instance if it accepts a particular symbol using #accepts?
+
+== 0.8.0, February 14th, 2009
 
 * Removed/deprecated :requiring option in favor of :accepts
 * CachingPresenter no longer tries to cache writer methods, ie; #foo=

lib/caching_presenter.rb

@@ -23,6 +23,10 @@ def respond_to?(*args)
     super || presents.respond_to?(*args)
   end
 
+  def accepts?(name)
+    @accepts.include?(name.to_sym)
+  end
+
   def self.inherited(subclass)
     write_presents_for_subclass subclass
     subclass.extend Memoizable
@@ -61,6 +65,7 @@ def write_constructor(options)
       constructor_options[:accepts] ||= []
       klass = self
       define_method(:initialize) do |args|
+        @accepts = constructor_options[:accepts].dup
         @presents_id = options[:presents]
         args = args.dup
         raise ArgumentError, "missing object to present on: #{@presents_id}" unless args[@presents_id]        

spec/caching_presenter_spec.rb

@@ -40,6 +40,12 @@ class NamedSpacedObjectPresenter < CachingPresenter
     SingleObjectPresenter.presents.should == :foo
     Class.new(SingleObjectPresenter).presents.should == :foo
   end
+
+  it "should be able to be queried for what it accepts" do
+    presenter = SingleObjectPresenter.new :foo => mock("foo")
+    presenter.accepts?(:bar).should be_true
+    presenter.accepts?(:unknown).should be_false
+  end
 
   %w(class id to_param).each do |method|
     it "should always delegate #{method} to the source of the presenter" do