Hi, I am working on a UI system. I have created a prototype factory using the regular pattern. The abstract "product" class (each product class takes only the "name" of the product as the parameter) which is the parent of all the product classes that the proto-factory creates, contains a lonnnnnng enumeration - each product class uses some of the enumerators contained inside the enumeration. Having developed the factory, I have realized that there are various other "thing" that I can "manufacture" using the same approach. So, I want to re-use the proto-factory. For that I need to templatize the product classes and the factory class and need to "manufacture" the proto-factory itself from a proto-factory generator class (another factory, that is). The problem is, the different enumerators/constants required by each product class don't allow me genericize the design. For example, I have an Align class which uses the following enumeration: enum text_align_type { text_align_not_set = -1, text_align_left = align_left_key, text_align_center = align_center_key, text_align_right = align_right_key, text_align_justified = align_just_key }; Now the Align class takes the string "Align" as its constructor parameter and sets one of its values to text_align_not_set using the initialization list. It makes use of all of the above enumeration constants in its validation and so on. Since the proto-factory is creating the products by cloning using the copy constructors of the registered objects, I think a solution would be to pass all these enumeration constants in the constructor of each product class (besides the productName argument which is already being passed to each product class constructor). This way, I will need to create/registered these products only once in the proto-factory registry and subsequent products will then be generated/manufactured (i.e. copy-constructed) from the registered products. PROBLEM ======== Passing enumeration constants in constructors for the sole purpose of validation, etc. seems to be a bit inefficient to me. Yet I also want to re-use the design. I wonder if I could use Boost and its template/meta-programming magic to somehow pass these enumeration constants to each product class without having to pass them in product class constructors. Any ideas? -Asif