Re: result of completing-read contradicting require-match

[carlmarcos]

Jul 2, 2022, 19:20 by bugs@gnu.support:

> * carlmarcos--- via Users list for the GNU Emacs text editor 
> <help-gnu-emacs@gnu.org> [2022-07-02 21:59]:
>
>> I am using completing-read that uses require-match, without initial-input 
>> and withoutdef.
>>
>> If I press return so that the input is neither "name" or "name-mode", it 
>> seems that an empty
>> string is returned.  The result seems to contradict require-match being `t'.
>>
>
> (let* ((cseq '("name" "name-mode"))
>  (csel (completing-read "Type: " cseq nil t nil)))
>  csel) ⇒ then after pressing ENTER I get: ""
>
>
> REQUIRE-MATCH can take the following values:
> - t means that the user is not allowed to exit unless the input is (or
>  completes to) an element of COLLECTION or is null.
> - nil means that the user can exit with any input.
> - ‘confirm’ means that the user can exit with any input, but she needs
>  to confirm her choice if the input is not an element of COLLECTION.
> - ‘confirm-after-completion’ means that the user can exit with any
>  input, but she needs to confirm her choice if she called
>  ‘minibuffer-complete’ right before ‘minibuffer-complete-and-exit’
>  and the input is not an element of COLLECTION.
> - a function, which will be called with the input as the parameter.
>  If it returns a non-nil value, the minibuffer is exited with that value.
> - anything else behaves like t except that typing RET does not exit if it
>  does non-null completion.
>
Have been playing with REQUIRE-MATCH being 'confirm, but there is not 
information
what to do if yao want to confirm.



> I guess that simple pressing of ENTER means "null" in this case.
> But if anything is chosen, then it must be an element of the
> collection.
>
> If you then add default, then it would get the first value:
>  
> (let* ((cseq '("name" "name-mode"))
>  (csel (completing-read "Type: " cseq nil t nil nil (car cseq))))
>  csel) ⇒ then after pressing ENTER I get: "name"
>
> other way to persist asking until you get the true result is here:
>  
> (defun rcd-repeat-until-not-empty-string (function &rest args)
>  "Repeat FUNCTION with optional ARGS until result is not empty string."
>  (let ((result))
>  (while (string-empty-p (setq result (apply function args))))
>  result))
>
> (defun my-fun ()
>  (let* ((cseq '("name" "name-mode"))
>  (csel (completing-read "Type: " cseq nil t nil nil nil)))
>  csel))
>
> In this case it will keep asking you until you enter something.
>
> (rcd-repeat-until-not-empty-string 'my-fun) ⇒ "name-mode"
>
>
> -- 
> Jean
>
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