(file-exists-p "") --> t??

(file-exists-p "") --> t??

[Alfred M. Szmidt]

Is it intended that file-exists-p returns t for the empty string?

Re: (file-exists-p "") --> t??

[Harald Hanche-Olsen]

+ "Alfred M. Szmidt" <ams@gnu.org>:

> Is it intended that file-exists-p returns t for the empty string?

I don't know if it is intended or not, but it does make some sort of
sense: Try (find-file "") to see for yourself what you get.

- Harald

Re: (file-exists-p "") --> t??

[Alfred M. Szmidt]

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   Date: Mon, 27 Apr 2009 14:12:42 +0200 (CEST)
   Cc: emacs-devel@gnu.org
   From: Harald Hanche-Olsen <hanche@math.ntnu.no>
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   Content-Type: Text/Plain; charset=us-ascii

   + "Alfred M. Szmidt" <ams@gnu.org>:

   > Is it intended that file-exists-p returns t for the empty string?

   I don't know if it is intended or not, but it does make some sort of
   sense: Try (find-file "") to see for yourself what you get.

I guess that makes sense, I am actually fiine with the behaviour,
other than it is annoying when you use file-exists-p in a loop, and
you start of with a empty string...

(let ((foo ""))
  (while (not (file-exists-p foo))
    (setq foo (generate-foo-some-how))))

Re: (file-exists-p "") --> t??

[Deniz Dogan]

2009/4/27 Alfred M. Szmidt <ams@gnu.org>:
> I guess that makes sense, I am actually fiine with the behaviour,
> other than it is annoying when you use file-exists-p in a loop, and
> you start of with a empty string...
>
> (let ((foo ""))
>  (while (not (file-exists-p foo))
>    (setq foo (generate-foo-some-how))))

Why not use the following?

(let ((foo (generate-foo-some-how)))
 (while (not (file-exists-p foo))
   (setq foo (generate-foo-some-how))))

--
Deniz

Re: (file-exists-p "") --> t??

[Harald Hanche-Olsen]

+ "Alfred M. Szmidt" <ams@gnu.org>:

> I guess that makes sense, I am actually fiine with the behaviour,
> other than it is annoying when you use file-exists-p in a loop, and
> you start of with a empty string...
> 
> (let ((foo ""))
>   (while (not (file-exists-p foo))
>     (setq foo (generate-foo-some-how))))

Ah, I see.

(let (foo)
  (while (not (file-exists-p (setq foo (generate-foo-some-how)))))
  (do-something-with-existing-file foo))

- Harald

Re: (file-exists-p "") --> t??

[Alfred M. Szmidt]

   > I guess that makes sense, I am actually fiine with the behaviour,
   > other than it is annoying when you use file-exists-p in a loop, and
   > you start of with a empty string...
   >
   > (let ((foo ""))
   >  (while (not (file-exists-p foo))
   >    (setq foo (generate-foo-some-how))))

   Why not use the following?

   (let ((foo (generate-foo-some-how)))
    (while (not (file-exists-p foo))
      (setq foo (generate-foo-some-how))))

You might be passing a counter to the function that generates the file name.