Re: menu-select doesn't respect COMPLETE_IN_WORD option

[Bart Schaefer <schaefer@brasslantern.com>]

On Wed, Jun 10, 2020 at 8:26 PM Alan <8fvebtoeq87@gmail.com> wrote:
>
> Yes, I've tried *not* setting the complete_in_word option, but then the _prefix completer doesn't work. See this (rather bizarre in my opinion) explanation from http://zsh.sourceforge.net/Guide/zshguide06.html:
>
> "One gotcha with the _prefix completer: you have to make sure the option COMPLETE_IN_WORD is set. That may sound counter-intuitive: after all, _prefix forces completion not to complete inside a word. The point is that without that option, completion is only ever tried at the end of the word, so when you type <TAB> in the middle of <prefix><suffix>, the cursor is moved to after the end of the suffix before the completion system has a chance to see what's there, and hence the whole thing is regarded as a prefix, with no suffix."

As you've noticed, I think this advice only applies when _prefix is
attempted after _complete, or possibly when the ALWAYS_TO_END option
is set (which by default it is not).  I don't think COMPLETE_IN_WORD
is relevant unless you want prefixes completed only when no other
possibility is found (which is probably what it was thought most
people would expect).

If someone has a chance to test a few combinations and update that
doc, please go ahead.  I might but I don't know how soon.

> (I'm not actually entirely clear how the completer ordering works, so not sure if I need that second _prefix instance at the end, but whatever works I guess. If someone would care to shed some light on the matter, that would be good too.)

The completion process happens in a nested loop:  For each function in
the completer list, try it with each of the patterns in the
matcher-list.  Ordinarily this loop stops as soon as one of the
completers returns zero (true), which is why the order is important,
but the _all_matches completer can change that.

The only reason to put _prefix in the list twice would be to implement
the example of doing so that appears in the documentation for _prefix.