From: Lars Ingebrigtsen <larsi@gnus.org>
To: Michael Albinus <michael.albinus@gmx.de>
Cc: Eli Zaretskii <eliz@gnu.org>, emacs-devel@gnu.org
Subject: Re: master e315544: ; * src/fileio.c (Fdirectory_append): Doc fix.
Date: Sun, 25 Jul 2021 07:19:12 +0200 [thread overview]
Message-ID: <87wnpfynqn.fsf@gnus.org> (raw)
In-Reply-To: <87zgubmt3z.fsf@gmx.de> (Michael Albinus's message of "Sat, 24 Jul 2021 21:04:00 +0200")
Michael Albinus <michael.albinus@gmx.de> writes:
> It's rather a nice to have. Sometimes, I have a list of file name
> fragments, and I hope to avoid the checks for being non-empty strings
> ...
>
> But I can do this in my code.
Thinking about it a bit more, I can see use cases where ignoring nil/""
would be useful (without making the function less difficult to reason
about). (And it's analogous to `concat', besides.) So I think I'll go
ahead and make that change...
>>> Furthermore, we have
>>>
>>> (directory-append "foo/" "/bar") => "foo//bar"
>>>
>>> I would expect "foo/bar", meaning that all leading slashes in COMPONENTS
>>> are removed.
>>
>> Well, I think that's over into DWIM-land again (which is what
>> expand-file-name does, and this function deliberately doesn't do).
>
> expand-file-name and file-name-as-directory are functions which call a
> handler, for example Tramp. directory-append is much cheaper, and if it
> could do this string handling, I could avoid those functions. It would
> be more performant.
The reason `directory-append' is useful as a function at all (instead of
just using `concat') is that we're very vague about the difference
between a directory name and a file name in Emacs. That is, we treat
"/tmp/" and "/tmp" as equivalent in more than 99% of cases when dealing
with directories. This has naturally led to people setting
`foo-directory' variables etc to something ending with a slash or not
arbitrarily, which again means that you can't just use `concat' to
construct file names.
But "/bar.txt" does not happen naturally as a leaf file name, so I think
it'd be counter-productive to have `directory-append' do anything
particular about the start of file name components.
By the way -- I'm not sure that `directory-append' is the best function
name here... `file-name-concat' would perhaps be more natural? But
it's really about directories... `directory-name-concat'? Hm.
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
next prev parent reply other threads:[~2021-07-25 5:19 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20210724171858.1726.43078@vcs0.savannah.gnu.org>
[not found] ` <20210724171900.4A26D20D0A@vcs0.savannah.gnu.org>
2021-07-24 18:39 ` master e315544: ; * src/fileio.c (Fdirectory_append): Doc fix Michael Albinus
2021-07-24 18:51 ` Lars Ingebrigtsen
2021-07-24 19:04 ` Michael Albinus
2021-07-25 5:19 ` Lars Ingebrigtsen [this message]
2021-07-25 5:27 ` Stefan Monnier
2021-07-25 6:54 ` Lars Ingebrigtsen
2021-07-25 10:01 ` Kévin Le Gouguec
2021-07-25 10:23 ` Lars Ingebrigtsen
2021-07-25 11:50 ` Andreas Schwab
2021-07-25 13:05 ` Kévin Le Gouguec
2021-07-28 15:39 ` Lars Ingebrigtsen
2021-07-28 17:28 ` Michael Albinus
2021-07-30 11:36 ` Lars Ingebrigtsen
2021-07-25 7:59 ` Michael Albinus
2021-07-28 15:36 ` Lars Ingebrigtsen
2021-07-28 17:13 ` Michael Albinus
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