Liliana Marie Prikler <liliana.prik...@gmail.com> writes:
> Am Donnerstag, dem 06.01.2022 um 02:20 +0100 schrieb Jelle Licht: >> > >> > >> > > Here’s a colour sample for the new bikeshed: >> > > >> > > (arguments >> > > (list >> > > #:patches >> > > #~(patch "the-file" >> > > ((line 10) >> > > (+ "I ONLY WANTED TO ADD THIS LINE")) >> > > ((line 3010) >> > > (- "maybe that’s better") >> > > (+ (string-append #$guix " is better")) >> > > (+ "but what do you think?"))))) >> > Now this thing is again just as brittle as the patch it encodes and >> > if I know something about context-less patches then it's that >> > they're super not trustworthy. >> >> What do you mean here, with 'brittle' and 'trustworthy'? Is it the >> fact that line numbers are hardcoded, compared to the substitute* >> approach? > What Ricardo is writing here as a colour sample is a context-less diff > and if you've ever worked with those, then you'll know they apply > exactly without context. So that line 10 is stuck there, it doesn't > move with regards to whatever entity is interesting at line 10. The > second hunk is better in that it needs a line to match and replace, but > it throws an error if it doesn't find that at line 3010, even if it'd > exist and 3020 or 2048. Yes, this example is context-less. But you know what it’s like looking at bikeshed colours on a screen: they just don’t pop right, and dependent on screen calibration or lack thereof they can seem outright hideous — nothing like the real thing. So lets take a step back and look at the location and shape of the bikeshed rather than its color. Do we agree that it would be lovely to have a less flexible but declarative pattern to describe changes to files? Less flexible than a full-blown editing DSL as that of Emacs, less flexible than perhaps arbitrary regular expression replacements as provided by substitute*? I just think that sometimes we want to focus on the change itself and not how we get there. It’s primarily a matter of style and readability. I think it’s regrettable to have all these boilerplate build phase shenanigans to express a simple change in a file. A large chunk of that is just boring set up work to be permitted to use “substitute*”, and then the “substitute*” itself is primarily concerned with an anchor that could not be much uglier: a regular expression DSL embedded in a string with double escaping. Yuck! Even something as simple as diff-in-a-string seems more appealing in some cases than all these “substitute*” expressions. -- Ricardo
