rule.rb in build-1.0.9

- old
+ new

@@ -46,17 +46,22 @@
 			
 			def dynamic?
 				@dynamic != nil
 			end
 			
+			# Do we have a default value for this parameter?
+			def default?
+				@options.key?(:default)
+			end
+			
 			def implicit?
 				dynamic? and @options[:implicit]
 			end
 			
 			# Optional parameters are those that are either defined as optional or implicit.
 			def optional?
-				@options[:optional] || implicit?
+				@options[:optional] || implicit? || default?
 			end
 			
 			def applicable? arguments
 				value = arguments.fetch(@name) do
 					# Value couldn't be found, if it wasn't optional, this parameter didn't apply:
@@ -78,10 +83,10 @@
 				elsif dynamic?
 					# Argument is optional:
 					scope.instance_exec(arguments[@name], arguments, &@dynamic)
 				else
 					arguments[@name]
-				end
+				end || @options[:default]
 			end
 			
 			def inspect
 				"#{direction}:#{@name} (#{options.inspect})"
 			end