> Except in very minor cases, duplication is virtually always worth fixing.
I disagree with the severity of this, and would posit that there are duplications that can't be "fixed" by an abstraction.
There are many instances I've encountered where two pieces of code coincided to look similar at a certain point in time. As the codebase evolved, so did the two pieces of code, their usage and their dependencies, until the similarity was almost gone. An early abstraction that would've grouped those coincidentally similar pieces of code would then have to stretch to cover both evolutions.
A "wrong abstraction" in that case isn't an ill-fitting abstraction where a better one was available, it's any (even the best possible) abstraction in a situation that has no fitting generalization, at all.
I disagree with the severity of this, and would posit that there are duplications that can't be "fixed" by an abstraction.
There are many instances I've encountered where two pieces of code coincided to look similar at a certain point in time. As the codebase evolved, so did the two pieces of code, their usage and their dependencies, until the similarity was almost gone. An early abstraction that would've grouped those coincidentally similar pieces of code would then have to stretch to cover both evolutions.
A "wrong abstraction" in that case isn't an ill-fitting abstraction where a better one was available, it's any (even the best possible) abstraction in a situation that has no fitting generalization, at all.