Think twice before pulling up

Pull up refactoring means that you move a member from a subclass to a superclass. It might be useful to remove duplicated code but it can also damage your design quite a lot.

A lot of times I wanted to perform pull up I came up with a better solution. The thing is that the behavior has to make sense in the context of the superclass. Yesterday I came up  with this code.


 This is the result of bad pull up refactoring. Some of the subclasses shared method CreateDirectionVector so I decided to pull it up to the parent. As you can see the method doesn’t really fit there. You can ask why is the WeaponBehavior responsible for carrying out this vector calculation. Also none of the other methods uses it so it isn’t obvious why the method even exists.

I have solved this by creating a class VectorUtilities and put the method there. I am always anxious when I want to create such class but I think in this case the Utility class is justifiable in my architecture.



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