Re: Turning completion table lambdas into symbols

[Dmitry Gutov]

On 29/11/2023 21:26, Spencer Baugh wrote:
> > For CAPF and Company, we also discussed the idea of a "session object"
> > some time ago, but that's not in the current API so far.
> Right, I think I'd much rather some kind of "session object" at the
> level of completing-read/the programmed completion API.
>
> Do you have a link to the previous discussion?

It's been here and there, but the last mention was right in the middle 
of this:

https://debbugs.gnu.org/cgi/bugreport.cgi?bug=47711#272
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=47711#320

> I haven't thought too much about it, but maybe some new dynamic variable
> which is bound to nil at the top level of completing-read-default, so
> the completion table can change it over time and preserve state through
> the course of the completion.  Works fine with nested completing-reads.

That could work. If you further progress on this (in a new thread?), I 
suggest you tag all the interested parties (or include Stefan, at least).

> Alternatively, if today a completion table is always invoked with the
> same current buffer (probably the case?), we could formalize that and
> just let a completion table store state in buffer-local variables.
> Maybe with some new 'initialize operation in completion tables which is
> called when a new completing-read starts, or maybe the completion table
> can just detect that somehow and initialize the variables itself.  That
> is nicer than having a single variable which all completion tables
> share.  However, completion table writers would need to be careful not
> to break when doing nested completing-reads on the same table.

It's not rocket science, but the hard part is to pick a protocol that's 
backward-compatible and weave it through all the related pieces of code.

Also see the note about backspacing around here: 
https://github.com/minad/corfu/wiki#configuring-corfu-for-eglot (where 
doing an edit before the current BEG doesn't abort completion but does 
make the cache invalid), but that might be something to handle in the 
caching logic anyway.