Re: [PATCH] Re: Other details about completion.

[Ergus]

On Thu, Apr 07, 2022 at 08:57:17PM +0300, Juri Linkov wrote:
> > > So why do you think that switching to the Completions window
> > > is required to select a completion candidate?
> >
> > Basically because we don't need that exact behavior in all the details
> > as our use case is a bit different different (and simpler). we use
> > single commands most if the time. I mean, most of the completion we need
> > are for single commands/candidates/files because we can't do things
> > like: "M-x find-file /my/file/path" in a single line. (there are some
> > exceptions line shell-commands or so... but those are the exception, not
> > the rule)
> >
> > But also because emulating that from completions is straight forward
> > considering that Completions is read-only and any edit attempt (insert a
> > letter) will emit an error we can handle moving to the minibuffer and
> > executing there whatever we need.
> >
> > zsh adds an extra space before the letter so even if it does not leave
> > the command line completely there is a switch to a state where arrows
> > navigate, a letter inserts a space and C-g restores to the initial... So
> > there is a mode and context change.
>
> So inserting a letter from the Completions buffer is the only thing
> that you miss from zsh? 

Actually yes, that and remove the mode-line to completions...

> But you also said above that this feature is
> not important because such cases are rare: "M-x find-file /my/file/path".
I can live with that. Lets say in our case adding a space does not make
much sense, but just inserting the letter in place without completion
may be a better behavior... But again... I can live with this.

> In all other regards, currently it works exactly like in zsh:
> 'TAB TAB' selects the Completions window, and C-g cancels it.
Yes...

> > > But in zsh <up> and <down> wrap to the top/bottom of the same column.
> >
> > Yes, I already implemented that and you didn't liked because it was a
> > bit long ;p... Now this is getting longer and longer....
>
> Indeed, its logic looks complicated.  But maybe we could implement
> simple rules like in zsh?  Then <up> ans <down> in the Completions
> buffer could be bound to new commands.
Let's cleanup master and move to our own branch then??

> > > Also in zsh TAB moves vertically when columns are sorted vertically.
> > > Shouldn't TAB in Emacs move vertically too when 'completions-format'
> > > is 'vertical'?
> >
> > Actually yes... But implementation will be long and ugly... I don't
> > think it worth it...
> >
> > The ideal case may be to have some modes completions-vertical,
> > completions-horizontal and completions-one-column that will handle all
> > the pack together (bindings, order, formats)... but may break some of
> > the external packages. Otherwise we will end with a code full of if-else
> > and hard to maintain or extend...
>
> Looks like the right thing to do.