Sorry for the delay and the scarce response... too much work.


El Thu, Oct 22, 2009 at 04:12:09PM -0400, Stefan Monnier ens deleità amb les següents paraules:
> > I don't know about the features of current code, but I miss some
> > features on some (if not all) the completion interfaces I've tested.
> > So here's a list of (my) desired features (all of which should be
> > configurable by the user):
> 
> Sounds interesting, but I must be missing some context because there's
> a lot of references I don't understand.  Could you expand on them?

Sure.


> > - symbol name
> >   Of course, this is what already provides every completion UI
> 
> No idea what you're talking about here.
> 
> > - extra information
> >   This can be filled ub with symbol "metadata".  Which metadata
> >   appears on the completion UI should be configurable by the user:
> >     - return type
> >     - arguments (type and/or name)
> >     - definition location (aka file)
> >     - short documentation
> >     - long documentation
> >   All this metadata should be located anywhere around the symbol name
> >   and/or the minibuffer (e.g., I think company-mode shows short
> >   documentation on minibuffer, until user presses F1, when full
> >   documentation is shown.  Some metadata might be shown in the
> >   minibuffer after completion selection (e.g., prototype).
> 
> Oh... wait, are you talking specifically about completion in code
> buffers, so "symbol name" above referred to the ability to complete an
> identifier?

That's right.


> As for this "extra info", I see what you mean, but usually completion
> involves several potential candidates, so listing them all plus all
> their info would take way too much space in general (if not, then
> something like completion-annotate-function should work).

What I described is similar to `completion-annotate-function', but more
flexible (prefixed in the symbol/identifier, postfixed; some in overlay, some in
minibuffer, etc).


> So usually this extra info is provided outside of the completion functionality
> (e.g. via eldoc-mode or something similar).  But, yes, I'd like to extend the
> *Completions* buffer so that you could ask for more info (either on all
> entries, or just on one at a time).

The key here is that completions do not necessarily have to go (only) into the
*Completions* buffer.


> > - result narrowing
> >   A-la company-mode.
> 
> No idea to what this is referring.

Company-mode provides a binding that, given the current table of possible
completions, the user can narrow it through various mechanisms (e.g., regexps).


> > - argument placeholders So that argument type and/or name is shown as
> > placeholders, such that the user simply TABs (or whatever) to fill-in
> > the blanks.
> 
> Idem.  Unless you mean something like skeletons/templates, but then
> I fail to see the connection with completion.

Completing a symbol triggers an arbitrary function, which could, for example:
    - show symbol definition
    - show short and/or extended documentation for symbol
    - insert skeleton/template-like symbol definition (such that user simply
      tabs to sellect next argument placeholder, which initially contains
      argument name and/or type).

This could be achieved if completions where "complex objects", so each could
describe what/where to show on the specific current completion UI, a "hover"
callback (e.g. show short doc or symbol signature on minibuffer), and a
selection callback (e.g., same possibilities as hover, plus the skeleton thing).

Read you,
    Lluis

-- 
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