bug#66224: [PATCH] Add optional PREDICATE argument to read-directory-name

[Joseph Turner]

Michael Heerdegen <michael_heerdegen@web.de> writes:

> Joseph Turner via "Bug reports for GNU Emacs, the Swiss army knife of
> text editors" <bug-gnu-emacs@gnu.org> writes:
>
>> I'm not sure what you mean. In both of the following examples, PREDICATE
>> is used to narrow the completion candidates to only empty directories:
>>
>> (read-directory-name "Prompt: " "~/" nil t nil #'directory-empty-p)
>> (read-directory-name "Prompt: " "~/" nil nil nil #'directory-empty-p)
>
> In the second version also non-empty directories will be accepted.

Yes, PREDICATE narrows the completion candidates but doesn't determine a
valid return value.