added support for methods without arguments

lib/ruby_memoized.rb

@@ -21,13 +21,15 @@ def method_added(method_name)
 
         unmemoized_method_name = :"unmemoized_#{method_name}"
 
+        accepts_arguments = instance_method(method_name).parameters.any?
+
         memoizer_name = :"memoizer_for_#{method_name}"
         define_method memoizer_name do
           memoizer = instance_variable_get "@#{memoizer_name}"
           if memoizer
             memoizer
           else
-            instance_variable_set "@#{memoizer_name}", Memoizer.new(self, unmemoized_method_name)
+            instance_variable_set "@#{memoizer_name}", Memoizer.new(self, unmemoized_method_name, accepts_arguments)
           end
         end
 

lib/ruby_memoized/memoizer.rb

@@ -1,15 +1,21 @@
 module RubyMemoized
   class Memoizer
-    attr_reader :context, :method
+    attr_reader :context, :method, :accepts_arguments
 
-    def initialize(context, method)
+    def initialize(context, method, accepts_arguments)
       @context = context
       @method = method
+      @accepts_arguments = accepts_arguments
     end
 
     def call(*args, **kwargs, &block)
       return cache[[args, kwargs, block]] if cache.has_key?([args, kwargs, block])
-      cache[[args, kwargs, block]] = context.send(method, *args, **kwargs, &block)
+
+      if accepts_arguments
+        cache[[args, kwargs, block]] = context.send(method, *args, **kwargs, &block)
+      else
+        cache[[args, kwargs, block]] = context.send(method)
+      end
     end
 
     def cache