GNU bug report logs - #23650
Use of locate-file for directories is underdocumented

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Nikolay Kudryavtsev <nikolay.kudryavtsev <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: Use of locate-file for directories is underdocumented
Date: Mon, 30 May 2016 01:44:11 +0300

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Hello.

Let's say I have a list of folders A, B, C. I want to find which one of 
them contains subfolder D.

My first idea was using locate-file. While doing so I've found that the 
Elisp reference for it is incomplete and confusing:

1. According to the docstring it would only return a directory if 
PREDICATE returns 'dir-ok. This is not mentioned in the Elisp reference.

2. The reference suggests file-directory-p as a useful predicate and 
this would fail due to 1.

3. It's probably a good idea to mention that there are no bundled 
predicates that return dir-ok, and suggest to use a lamda like this: 
(lambda (f) (and (file-directory-p f) 'dir-ok)) as a PREDICATE.


Here's a working example, just in case:

(locate-file "Git" '("c:/Program Files/") nil (lambda (f) (and 
(file-directory-p f) 'dir-ok)))

-- 
Best Regards,
Nikolay Kudryavtsev

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