Re: font-lock-syntactic-keywords obsolet?

[Dmitry Gutov]

On 06/21/2016 01:45 AM, John Wiegley wrote:

> There is really no need for this kind of tone. Alan is striving to solve a
> problem;

No, he's not. He doesn't have a specific problem he's trying to solve, 
just a lot of opinions and one flimsy, tangentially related, bug report.

What he's doing, third time around now (?), is making misleading 
comments in public, then arguing a lot, and never budging in his stance 
one iota.

If you think my comments are not helpful, I can shut up, of course. And 
save a lot of time doing that.

> let's help him find the best solution, rather than criticizing his
> efforts. If before/after-change-functions is not a general solution as-is, all
> we need are some examples to demonstrate this.

I gave several explanations and examples. There is no way I can continue 
doing that if the explanations are waved off with opinionated "bad 
design" comments, and examples with "I've never had that kind of problem".

Here's an example in Ruby:

    a = `def

    b = :`

If you add ` at the end of the first line, the code will have one 
meaning (with the last ` character having syntax-table property 
"symbol"). Without it, another meaning, and no syntax-table property on 
the last character.

Now mentally insert 300000 lines of code between these lines, none of 
them containing the character `. And imagine yourself adding and 
removing the ` character at the end of the first line.

If Emacs is supposed to keep the syntax-table value on the last 
character up to date using after-change-functions, it will have to scan 
the whole 300000 line buffer after every keypress.

Addendum:

With clever enough caching (to be implemented by someone highly 
motivated), I suppose it's possible to avoid having this problem on 
*every* keypress. But having to do that even on some of them is bad enough.