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Re: [Emacs-diffs] master 3431e82: Ignore directory symlinks in directory
Lars Magne Ingebrigtsen
Re: [Emacs-diffs] master 3431e82: Ignore directory symlinks in directory-files-recursively
Fri, 16 Jan 2015 01:08:00 +0100
Gnus/5.130012 (Ma Gnus v0.12) Emacs/25.0.50 (gnu/linux)
Stefan Monnier <address@hidden> 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
>>> 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
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