bug#35508: 27.0.50; Fine-ordering of functions on hooks

[Stefan Monnier]

>> Other objections?
> Thanks.  Should we perhaps change 100 to 110 and 90 to 100?

You mean make it go https://en.wikipedia.org/wiki/Up_to_eleven ?  ;-)

> And perhaps not document the 110 value?  Just a thought.

I think we do want to document values greater than what `t` does: it can
be important (e.g. for syntax-ppss-flush-cache) to make sure we stay
closer to the end than those hooks appended via `t` for weaker reasons
(e.g. because they don't want to be before some other function, although
they don't really care if they're the very last one or not).

Also I think it's important to use the same convention as for add-function.

But what I wonder is whether we should enforce the convention: currently
we don't in add-function (and in this add-hook patch), so you can use
a depth of 8345 if you feel like: it's really just a convention.

Also, maybe the docs should insist on the fact that 100/-100 should
basically never be used since they imply that you're 100% sure that
noone will ever need to come before/after you, and you can never be sure
100%.


        Stefan