Re: completing-read depricated initial-input

[carlmarcos--- via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org>]

Jun 23, 2022, 07:59 by arash@gnu.org:

> Drew Adams <drew.adams@oracle.com> writes:
>
>>> > `completing-read' is extremely general, allowing for many different
>>> > interactions for many different kinds of use cases.
>>>
>>> True, unfortunately.
>>>
>>
>> Why "unfortunately"?
>>
>
> Because extremely general tools give one many ways to do things.  It is
> just hard if you find out afterwards that things went in the wrong
> direction and you try to clean up.  No other reason.
>
>> And there's `read-from-minibuffer', which is
>> even more general.
>>
>
> Therefore we have `read-string'.
>
>> I'd rather have Emacs implement, test, and maintain it than do so
>> myself, if possible. ;-)
>>
>
> Good strategy ;-)
>
>>> but you're still free to use the old feature if you
>>> think it has a added value from a user perspective.
>>>
>>
>> Sure.  With the risk that what's deprecated might be
>> desupported at some point.
>>
>> (At which point you can always choose to copy the old
>> code and continue to use it.  With the bother of
>> dealing with incompatibilities, inconsistencies, and
>> having to keep some bits synchronized...)
>>
>
> I don't think this will happen for `completing-read'.  Looking at other
> places than the docstring of `completing-read', you find:
>
>  • Emacs Lisp Ref:
>
>  21.5 Initial Input[1]
>
>  Several of the functions for minibuffer input have an argument called
>  initial. This is a mostly-deprecated feature for specifying that the
>  minibuffer should start out with certain text, instead of empty as
>  usual. [...]
>
>  We discourage use of a non-nil value for initial, because initial
>  input is an intrusive interface. History lists and default values
>  provide a much more convenient method to offer useful default inputs
>  to the user.
>
>   21.6.2 Completion and the Minibuffer[2]
>
>  Function: completing-read [...]
>  The argument initial is mostly deprecated; we recommend using a
>  non-nil value only in conjunction with specifying a cons cell for
>  history. See Initial Input. For default input, use default instead.
>
This is where I disagree.  The documentation discouraging and recommending
not to use it, reads as a statement that lacks any persuasive discussion.

It is not valuable to discourage something simply because it is usually found that
 it is empty.  A designer might know better what he is trying to achieve.  At times it
is better to display some indicative words to the user, than nothing at all (an empty field).

INITIAL-INPUT allows one to display a personally preferable feature whilst keeping
the usual default intact. One must not confuse "initial" with "default".  An initial value
could be assigned to some preferential usage that differs from some well known canonical
 setting.

    



>  • `read-string' docstring:
>
>  Read a string from the minibuffer, prompting with string PROMPT.
>  If non-nil, second arg INITIAL-INPUT is a string to insert before reading.
>  This argument has been superseded by DEFAULT-VALUE and should
>  normally be nil in new code.  It behaves as INITIAL-CONTENTS in
>  ‘read-from-minibuffer’ (which see).
>
> Note the terms "mostly-deprecated", "discourage", "recommend",
> "superseded".  So maybe the docstring of `completing-read' should be
> adjusted to the statements above in order to avoid confusion?
>
I do not see that the deprecation was superceded through some improved
 coding mechanism.


> Best, Arash
>
> Footnotes:
> [1]  https://www.gnu.org/software/emacs/manual/html_node/elisp/Initial-Input.html
> [2]  https://www.gnu.org/software/emacs/manual/html_node/elisp/Minibuffer-Completion.html
>