Hacker News Reader

Comment by hinkley | Hacker News Reader

I’ve come to the conclusion that half or more of the rules we have about “clean” are about avoiding merge conflicts. Few things have been consistently disappointing to me as the inability of coworkers and myself to reason about merges correctly. There are three hard things in software and merges are #3.

If anyone ever figures out how to make merges Just Work, then I expect a lot of pressure toward decomposition over locality would be reduced, and much of the rest would be to facilitate testing.

View on HN

An interesting point.

I think it would be better to merge ASTs rather than text files that represent code. The annoying issues with merges are all about the text representation. When there's actually different logic changes in two different directions the merges cease to be annoying and start to require domain knowledge.

Of course getting from this hand-wavey thought to working software is difficult. Perhaps we first need to start focusing more on the tree nature of code even in the editing tools?

I wish I kept better bookmarks. There was a project years ago where the diff tool had a tokenizer per language so that it could diff the code similarly to what you suggest. Obviously it did not take over the world.

But yes, that should help.

It always annoys me that I add a method and the diff tool says that I inserted code before the last curly bracket for the previous function, instead of balancing the brackets.

Can you elaborate a little please? It's unclear to me if you are taking about merging data, code changes, or something else

I’m assuming it was a reference to merging in source control. A lot of “noise” in diffs, and by extension in merges and the sometimes awkward job of resolving merge conflicts, comes from little details like whitespace and punctuation rather than substantial semantic changes in the code. Many a coding standard, and even a language change from time to time, has been made with this in mind, sometimes to the point of putting punctuation in odd places or avoiding aligning items using extra whitespace just to minimise the number and/or size of diffs to check.

Code changes are adding or correcting behavior. A lot of coding practices tend to help two things: reading comprehension and keeping developers from bumping into each other. Adding code to the same areas and then having to handle merge conflicts without introducing regressions. It’s much simpler to segregate the code into separate concerns so that new features do not intersect.

But too much decomposition also hurts reading comprehension. So if the specter of merge conflicts went away you’re left with readability, which will settle out to somewhere between the extremes of decomposition. I’m suggesting that would result in somewhat larger methods. Especially where crosscutting concerns intersect each other.

Reply on news.ycombinator.com