bug#11906: 24.1; completion-at-point failures

[Leo Liu <sdl.web@gmail.com>]

On 2013-05-11 04:36 +0800, Stefan Monnier wrote:
> <fiddling around some more>
>
> Ah, OK.
> so I should type RET before "history 10", so history shows me the last
> commands run by octave.

Sorry, I wasn't clear.

> The difference between 2 and 3 calls shouldn't be sufficiently large to
> go from "acceptable" to "terrible delay".

It is a difference between 1 and 3 calls because a user can also run
octave in terminal and find that how responsive it actually is.

I noticed this long delay when completing empty strings
(octave-completion-at-point used to allow empty strings). Emacs will be
busy for a few seconds (something like 3 ~ 5 seconds in my laptop).
Given how often I use the TAB key, it was terrible experience.

> Using a cache is a good idea: when there's no completion, the completion
> code may call the completion-table many more times than just 3 times
> (typically, it will call it at least once per completion-style).

I just want to point out these problems in the completion-at-point
machinery.

I think if completion-at-point can work well when there is a 2-second
cost in a completion-at-point function, it can provide an excellent
experience.

>         Stefan

Thanks,
Leo