[horsawlarway]

> I'm taking about scenarios where the business logic needs to be exactly the same in both cases, there just happens to multiple ways to reach that point.

I've seen lots of these cases turn out to be "the business logic happens to be exactly the same in both cases".

It might have been a single feature at one point where it should have been identical, but two flows going there in two different ways means it's serving two masters. Often it will diverge as the product grows and those flows become their own features with differing requirements.

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And also - "it takes less thought/time to copy and paste a few lines of code than it does to factor them out into a reusable function and decide where to put it (and with what name)."

Yes, that's the point. It takes both less time and thought, and it often diverges anyways. You are wasting time and creating complexity.

[wizofaus]

But the divergence is more often than not unintended and causes inconsistent/ unexpected behaviour when a change is made in one copy and not the other, which is why it ends up using up more time in the end. And how is extracting a few lines of code into a function and calling that more complexity than having two identical copies of it?

[IggleSniggle]

When the divergence comes from subtle differences in requirements, then those subtle differences in requirements now need to baked into your single function (or, really, broken out from the function; but they have to be recognized as different to begin with). Now, the next time you need to address a new feature along one pathway, you must also be certain that you are not subtly breaking some completely unrelated feature requirement.