From: Lars Magne Ingebrigtsen <larsi@gnus.org>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: emacs-devel@gnu.org
Subject: Re: [Emacs-diffs] master 3431e82: Ignore directory symlinks in directory-files-recursively
Date: Fri, 16 Jan 2015 01:08:00 +0100 [thread overview]
Message-ID: <m3oapzbna7.fsf@gnus.org> (raw)
In-Reply-To: <jwvlhm0l7i1.fsf-monnier+emacsdiffs@gnu.org> (Stefan Monnier's message of "Sun, 21 Dec 2014 22:02:40 -0500")
Stefan Monnier <monnier@iro.umontreal.ca> writes:
>>> It can avoid calling expand-file-name only to call file-name-directory
>>> (or file-name-nondirectory) right after.
>> It can, but in the use cases I've typically seen, you wouldn't do that,
>> I think? You'd say `(directory-name-p file)' and then... something...
>
> I don't understand what you mean here. I'm just pointing out that
> calling expand-file-name only to pass the result to the function
> parameter means that this work may be wasted.
>
> So passing the two parameters separately is a way to be more lazy.
The typical usage (in the callers that call versions of this function
other places in the Emacs tree) seems to be "give me a list of files
matching this regexp". Making the callers take a separate directory and
leaf name makes the caller do the work of joining those two things up
before anything can be done, so it's more lazy to have the
`directory-files-recursively' do this work.
If there are callers that also want directories, they will have to do
more work, but that extra work is just calling `directory-name-p', which
is a very cheap function.
So I don't really see any advantage to having two parameters in the
callback function.
>>> Can we reduce the number of arguments?
>> That would be nice, but I'm not sure what to remove. The canonical,
>> that most of the callers use (from the other versions of this function
>> included in various packages in Emacs) is
>> (directory-files-recursively "~/" "~\\'")
>> or something. And then there are a couple that want the directories,
>> too. And then there's `file-tree-walk', which is the new thing.
>
> Exactly: the use cases are varied, so we need a very generic interface.
> I actually find file-tree-walk not too bad in this respect.
>
>> Uhm... we could make MATCH be the predicate if it's not a string?
>
> But we need 2 answers: whether to include the file in the result, and
> whether to recurse.
Er, huhm, yes, I don't know what I was thinking.
Then I don't really see any practical way to reduce the number of
parameters below four. We could drop INCLUDE-DIRECTORIES, but then the
somewhat handy `(directory-files-recursively "/tmp/foo" "." t)' (to do
`rm r') wouldn't be as handy any more.
>> Right. But do we have a word for "string that designates either a file
>> or a directory"?
>
> Yes, we say "a file name". A directory is a kind of file.
Ok; I'll rename away.
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
prev parent reply other threads:[~2015-01-16 0:08 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20141212105304.4186.22515@vcs.savannah.gnu.org>
[not found] ` <E1XzNqL-000168-2E@vcs.savannah.gnu.org>
2014-12-12 14:57 ` [Emacs-diffs] master 3431e82: Ignore directory symlinks in directory-files-recursively Stefan Monnier
2014-12-13 15:01 ` Lars Magne Ingebrigtsen
2014-12-14 4:59 ` Stefan Monnier
2014-12-14 9:33 ` Lars Magne Ingebrigtsen
2014-12-14 14:27 ` Stefan Monnier
2014-12-21 11:57 ` Lars Ingebrigtsen
2014-12-22 3:02 ` Stefan Monnier
2015-01-16 0:08 ` Lars Magne Ingebrigtsen [this message]
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