> Do we care that using save-match-data in every call to replace-match
> might mean a performance hit?
I do but:
- to be honest, it's probably lost in the noise.
- if we copy search_regs.start and search_regs.end with something like
alloca+memcpy (instead of calling Fmatch_data), the cost should be even more
lost in the noise. Especially if you consider that the current code
already loops through the match-data to adjust it.
- it's the best fix we've found so far.
> If it will, then this will again punish
> most of the users for the benefit of those few who (1) have
> buffer-modification hooks, and (2) those hooks call save-match-data.
I think the combination of 1 and 2 is actually pretty frequent.
Stefan
PS: I can think of one (theoretical) other/better way to fix this
problem: move the match-data adjustment so it's done within
replace_range before running the after-change-functions. I think
this would be very satisfactory, since it would mean that the Elisp
code would always see the valid match-data (whereas currently the
after-change-functions get passed not-yet-adjusted match-data), so
save-match-data wouldn't mess it up. But I fear this would require
much larger changes (and might involve a heavier performance cost as
well).
