How much duplicated code do you tolerate? [closed]

Answer 1

It really depends on many factors, how much the code is used, readability, etc. In this case, if there is just one copy of the code and it is easier to read this way then maybe it is fine. But if you need to use the same code in a third place I would seriously consider refactoring it into a common function.

Answer 2

Personally, I prefer keeping code understandable, first and foremost.

DRY is about easing the maintenance in code. Making your code less understandable in order to remove repeated code hurts the maintainability more, in many cases, than having some repeated lines of code.

That being said, I do agree that DRY is a good goal to follow, when practical.

Answer 3

Refactoring: Improving the Design of Existing Code

The Rule of Three

The first time you do something, you just do it. The second time you do
something similar, you wince at the duplication, but you do the duplicate
thing anyway. The third time you do something similar, you refactor.

Three strikes and you refactor.

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Coders at Work

Seibel: So for each of these XII calls you're writing an implementation.
Did you ever find that you were accumulating lots of bits of very similar code?

Zawinski: Oh, yeah, definitely. Usually by the second or third time you've cut and pasted
that piece of code it's like, alright, time to stop cutting and pasting and put it in a subroutine.

Answer 4

The point of DRY is maintainability. If code is harder to understand it's harder to maintain, so if refactoring hurts readability you may actually be failing to meet DRY's goal. For less than 15 lines of code, I'd be inclined to agree with your classmate.

Answer 5

Very difficult to say in abstract. But my own belief is that even one line of duplicated code should be made into a function. Of course, I don't always achieve this high standard myself.

Answer 6

I tolerate none. I may end up having some due to time constraints or whatnot. But I still haven't found a case where duplicated code is really warranted.

Saying that it'll hurt readability only suggests that you are bad at picking names :-)