Nobody argues with SRP in principle. Every developer I’ve worked with agrees a function should do one thing. The argument is always at the example, whether a given function is one thing or six, and that is the part the rule itself doesn’t settle.
Two things have done most of the work for me.
The name. If you need an “and” to describe what the function does, it’s two jobs. Saying it out loud forces the description to be honest, and once you have said “it validates the order and then submits it” the extraction is obvious without anyone arguing about line counts.
The actor question, from Clean Architecture: who pays when this changes. Two sets of people filing bugs against the same function is a boundary problem however short that function is. Parnas got to the same place in 1972 by listing the design decisions likely to change and giving each one a module that hides it.
Length and complexity limits catch the same smell and I do run them, but they are proxies. A long function with a single reason to change is fine, and a short one serving two teams isn’t.
This has mattered more since agents started writing the first draft. A developer reading a fuzzy boundary works the intent out from the surrounding code. An agent takes the boundary as given and builds on it.
I write these up at https://prickles.org/tenet/single-responsibility-principle/F1 if the longer version is useful.
;AIDR
That headline uses a VERY common LLM telltale phrase formula. I’m repulsed by it and refuse to read on.
Like many “rules” of programming it’s actually more of a “guideline”. You can write pages defining the rule and all of the scenarios but it’s wasted effort IMO. Follow the “role” reasonably and discuss it during code review if it seems like something should be refactored.
I think SRP is separate from LoC (lines of concern). You can have a function that does a single thing, but if it’s invoked across two LoC you’ll eventually have a bad time. LoC is the counter example to DRY.
Anyway, I’m sure the write up is fine. I think all of this is just to get people thinking about these things. If you have all of these acronyms in your head as you plan you’re less likely to have a mess on your hands 2 years down the road, and none of them will save you on its own.