Question

I just found myself creating a class called ‘InstructionBuilderFactoryMapFactory’. That’s 4 ‘pattern suffixes’ on one class. It immediately reminded me of this:

http://www.jroller.com/landers/entry/the_design_pattern_facade_pattern

Is this a design smell? Should I impose a limit on this number?

I know some programmers have similar rules for other things (e.g. no more than N levels of pointer indirection in C.)

All the classes seem necessary to me. I have a (fixed) map from strings to factories – something I do all the time. The list is getting long and I want to move it out of the constructor of the class that uses the builders (that are created by the factories that are obtained from the map…) And as usual I’m avoiding Singletons.

Answer 1

I see it as a design smell – it will make me think if all those levels of abstraction are pulling enough weight.

I can’t see why you wanted to name a class ‘InstructionBuilderFactoryMapFactory’? Are there other kinds of factories – something that doesn’t create an InstructionBuilderFactoryMap? Or are there any other kinds of InstructionBuildersFactories that it needs to be mapped?

These are the questions that you should be thinking about when you start creating classes like these. It is possible to just aggregate all those different factory factories to just a single one and then provide separate methods for creating factories. It is also possible to just put those factory-factory in a different package and give them a more succinct name. Think of alternative ways of doing this.