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* bug#27798: Documentation of locate-dominating-file is wrong
@ 2017-07-23  9:49 Clément Pit--Claudel
  2017-07-23 14:31 ` Eli Zaretskii
  0 siblings, 1 reply; 7+ messages in thread
From: Clément Pit--Claudel @ 2017-07-23  9:49 UTC (permalink / raw)
  To: 27798


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The docs of locate-dominating-file say this:

  (locate-dominating-file FILE NAME)

  Look up the directory hierarchy from FILE for a directory containing NAME.
  Stop at the first parent directory containing a file NAME,
  and return the directory.  Return nil if not found.
  Instead of a string, NAME can also be a predicate taking one argument
  (a directory) and returning a non-nil value if that directory is the one for
  which we’re looking.

This part is wrong, because locate-dominating-file also accepts directories:

  Look up the directory hierarchy from FILE

This part is wrong, because the predicate is called with the initial file name, too:

  NAME can also be a predicate taking one argument (a directory)

Indeed, the following form:

  (locate-dominating-file "/usr/local/bin/emacs" (lambda (x) (ignore (message "%s" x))))

prints this:

  /usr/local/bin/emacs
  /usr/local/bin/
  /usr/local/
  /usr/
  /

(not the file name passed into the first call.

I think the fix is to update the docs in both places, as there might be callers relying on the existing behavior.  It's important to also document that passing a directory name is OK, though, because that's the only way to use locate-dominating-file reliably with a directory-only predicate — otherwise, the predicate needs to handle both files and folders.

Cheers,
Clément.


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^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2017-07-28  9:59 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2017-07-23  9:49 bug#27798: Documentation of locate-dominating-file is wrong Clément Pit--Claudel
2017-07-23 14:31 ` Eli Zaretskii
2017-07-23 14:52   ` Clément Pit--Claudel
2017-07-23 15:20     ` Eli Zaretskii
2017-07-23 16:08       ` Clément Pit--Claudel
2017-07-28  9:39         ` Eli Zaretskii
2017-07-28  9:59           ` Clément Pit--Claudel

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