Is this Factory Method creation pattern?

Question

I have been using factory method creation pattern for awhile now. I was just recently told that this:

public static class ScheduleTypeFactory
{
    public st         


        

Answer 1

Yup, that's the factory pattern alright. Your Tech lead is wrong.

Answer 2

Take back the power right now! Just drop 'Type' from the wording. ScheduleFactory FTW. Wait, is this a factory for 'Schedules' or 'ScheduleItems'? If it's scheduleitems then the factory should be called 'ScheduleItemFactory'. Be expressive!!!

Answer 3

Your code fragment is what in Head First Design Patterns is called "The Simple Factory" (p. 117).
The main difference to the Factory Method Pattern is the ConcreteCreator (compare the diagram in the upper right corner), which is a simple class in your case.
In the "real pattern" the factory class is abstract with an abstract factory class. So, there is one more abstraction level. However, for many use cases, your Simple Factory is enough.

Simple Factory Simple Factory http://yuml.me/7221a4c9 Factory Method Pattern Factory Method Pattern http://yuml.me/3d22eb4e

Answer 4

Yes this is a factory pattern. My only comment would be that you fail silently for enum values that you don't specifically handle. That may be expected but I like to add the following to the end of statements like that

default:
  throw new InvalidOperationException("Invalid Enum Value");

Answer 5

Looks like a basic factory pattern to me. I'm curious to hear why your tech lead doesn't think this is a pattern.

I'm also dissapointed she wouldn't take the time to explain things. Having been a tech lead before on a team, it is curcial to take the time to explain your decisions.

Answer 6

I would agree to call the method a "Factory Method", though the design is not strictly a "Factory Method Pattern".
Here is a key point (from Wikipedia):

...The Factory method lets a class defer instantiation to subclasses."

Since your class is static and method static (hence non-virtual), there is no "deferring" possible.

Conceptually, notice also, that this implementation, though provides encapsulation, does not decouple/delay any decision.

Having said that, same Wikipedia article does present this schema as a variant of the "Factory Method Pattern".

Summary of the Summary: In my opinion this snippet is not a proper implementation of the "Factory Method OO Design Pattern", since it does not satisfy "a class defer instantiation to subclasses." Though, personally I would freely refer to this solution as "factory method".

To make it real factory method pattern, you need to allow the method to be overridden by subclasses. I.e. factory class (ScheduleTypeFactory) needs to be extensible (i.e. non-static), and GetScheduleItem needs to be virtual.