Re: RE: [External] : Doc of deprecated INITIAL-INPUT arg of completing-read

[Christopher Dimech]

> Sent: Tuesday, June 28, 2022 at 4:33 AM
> From: "Drew Adams" <drew.adams@oracle.com>
> To: "Michael Heerdegen" <michael_heerdegen@web.de>, "Emacs Development" 
> <emacs-devel@gnu.org>
> Subject: RE: [External] : Doc of deprecated INITIAL-INPUT arg of 
> completing-read
>
> > there was a long discussion in emacs-help about the INITIAL-INPUT
> > argument of `completing-read'.  Among other things people complained
> > about the argument being deprecated.
> >
> > I agree that it's not good to use it in nearly all cases, but there ARE
> > a few cases where it hardly can be avoided - we have over 30 uses in
> > Emacs itself.  So I want to suggest to change the docstring to warn
> > strongly about the usage of that argument, but stop saying it would be
> > deprecated.
> >
> > This is to make the current state of the code more consistent - I don't
> > plan to work on changes that had been suggested in that discussion.
> >
> > So would this patch be ok to install for now?
>
> FWIW, for my part I disagree that any "warning"
> is warranted.  There's nothing dangerous to warn
> about.
>
> I disagree with this (as I also disagree with the
> deprecation):
>
>   Using this argument is strongly discouraged--it is
>                          ^^^^^^^^^^^^^^^^^^^^
>   normally best to pass nil for INITIAL-INPUT and
>   ^^^^^^^^^^^^^
>   supply the default value DEF except in few special
>                                ^^^^^^^^^^^^^^^^^^^^^
>   cases like inserting a prefix common to all
>   completions or an initial part of a file name.
>
> There's zero reason to discourage its use in any
> blanket way, let alone "strongly" discourage.

I agree that there exists no reason to discourage it.
Nothing bad or difficult happens when it is used.


> INIT and DEF are different in behavior, and thus
> in use cases.  Telling users to use one of them
> _instead of_ the other is misguided, IMO.
>
> All that's needed is to make clear that INIT
> isn't intended as a _substitute_ for a default
> value - and vice versa.  That's really the point
> (IMO).  The use cases of INIT are different from
> those of DEF.  That's what should be made clear.
> Then leave it up to coders to use each as they
> see fit.

Right.  When people start mixing things up or hack their way to
things that creates confusion, the solution in for them to stop
with such approaches.


> But the confusion over their different uses is
> related to a missing feature, IMO, which is the
> ability for users to automatically insert the
> DEF value (not INIT) into the minibuffer, as an
> alternative to using `M-n' to insert it.
>
> Neither alternative is absolutely "better" than
> the other - this is naturally a user preference.
>
> The mistakes made in deciding to deprecate (or
> discourage) INIT-INPUT are two: (1) confusing
> it with a default value - DEF is no substitute
> for INIT, and (2) thinking that it's never a
> good UI to insert default values (DEF) in the
> minibuffer.
>
> #1 should be fixed by removing the deprecation
> and explaining the difference between the two
> (not by warning not to use INIT).
>
> #2 should be fixed by letting _users_ decide
> which DEF-inserting behavior they prefer: (1)
> automatic or (2) manual (`M-n').
>
> The choice of whether DEF should be inserted in
> the minibuffer should be up to users.  It's not
> for Emacs to decide for all and always which UI
> behavior (auto or `M-n') is better for everyone.
>
> If a user often wants to use (edit or choose)
> the default value then s?he might well want it
> to be inserted in the minibuffer.  If a user
> rarely uses the default value then s?he might
> want to insert it only manually, with `M-n'.
>
> That's really what it comes down to: having to
> delete DEF manually, if you don't want it, or
> having to insert it manually, if you do.
>
> (This is somewhat akin to the choice of whether
> to use `delete-selection-mode'.)
>
> In the help-gnu-emacs discussion you cited, I
> detailed what I would propose for #2 - I won't
> repeat details here.  I'll just say that users
> should have some way to choose whether DEF is
> to be automatically inserted in the minibuffer.
>
> (I also said there that they should have a way
> to choose whether it's inserted in the prompt.
> With my proposal, when DEF's auto-inserted in
> the minibuffer it's not inserted in the prompt,
> but users can also choose to never insert it
> in the prompt.)
>
> In any case, a missing insert-DEF-in-minibuffer
> behavior is 100% _independent_ of INIT-INPUT,
> which, yes, shouldn't be deprecated.
>
>