Good Software Development Habits

> It's better to have some wonky parameterization than it is to have multiple implementations of nearly the same thing. Improving the parameters will be easier than to consolidate four different implementations if this situation comes up again.

Hard disagree. If you cant decompose to avoid "wonky parameters" then keep them separate. Big smell is boolean flags (avoid altogether when you can) and more than one enum parameter.

IME "heavy" function signatures are always making things harder to maintain.

I think it's especially bad advice with the "copy paste once is okay". You absolutely do not want multiple (even just two) copies of what's meant to be exactly the same functionality, since now they can accidentally evolve separately. But coupling together things that only happen to be mostly similar even at the expense of complicating their implementation and interface just makes things harder to reason about and work with.

My experience is totally different. Sure the popular beginners advice is to never repeat yourself, but in many cases that can actually be a viable operation, especially when you are okay with functions drifting apart or the cases they handle are allowed to differ.

And that happens.

The beginners problem lies in the reasons why that happens — e.g. very often the reason is that someone didn't really think about their argument and return data types, how functions access needed context data, how to return when functions can error in multiple ways etc, so if you find yourself reimplementing the same thing twice because of that — sure thing, you shouldn't — what you should do is go back and think better about how data is supposed to flow.

But if you have a data flow that you are very confident with and you need to do two things that just differ slightly just copy and paste it into two distinct functions, as this is what you want to have in some cases.

Dogmatism gets you only so far in programming.

I think a part of the problem is that in addition to being a well regarded principle with a good pedigree, "DRY" is both catchy and (unlike SOLID or similar) seems self explanatory. The natural interpretation, however, doesn't really match what was written in The Pragmatic Programmer, where it doesn't speak of duplicate code but rather duplicate "pieces of information". If "you are okay with functions drifting apart or the cases they handle are allowed to differ" then the two functions really don't represent the same piece of information, and collapsing them may be better or worse but it is no more DRY by that definition.

I've tried to counter-meme with the joke that collapsing superficially similar code isn't improving it, but compressing it, and that we should refer to such activity as "Huffman coding".

It's also worth noting that the focus on syntax can also miss cases where DRY would recommend a change; if you are saying "there is a button here" in HTML and also in CSS and also in JS, your code isn't DRY even if those three look nothing alike (though whether the steps necessary to collapse those will very much depend on context).

The book assumes that you should know better, that’s the problem. You may understand it correctly and do your best, but remain unsure if that “piece of information” is the same with that one or not, cause it’s open for interpretation.

Uncertainty as to the line between "one piece of information" and "two pieces of information" may be a problem. I don't think it makes sense to say it's "the problem" when most people don't know that DRY is formulated in those terms in the first place.

Personally, I don't think the ambiguity is actually much of a problem; often it's not ambiguous, and when it is it's usually the case that multiple ways of organizing things are reasonably appropriate and other concerns should dominate (they may need to anyway).