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Re: empty-directory predicate, native implementation
From: |
Michael Albinus |
Subject: |
Re: empty-directory predicate, native implementation |
Date: |
Sun, 18 Oct 2020 14:06:30 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) |
Arthur Miller <arthur.miller@live.com> writes:
Hi,
>> But my argument wasn't about implementation or
>> efficiency. Even if, for some reason, C had to "get"
>> (info about) all of the files in the directory, just
>> to determine whether the dir is empty, my argument
>> would be the same wrt Lisp: have a separate predicate,
>> or have a Boolean new parameter, instead of having a
>> COUNT new parameter.
>
> I am not sure I follow; but it is a building block to build that
> predicate. I agree with you that it is much nice to have such predicate
> built-in than if anyone is building their own if it is just one liner.
>
> I have no problems to build that predicate on directory_files_internal
> either, it is trivial; and it would remove need to change the function
> signature and count confusion, but than instead of changing one
> parameter in a signature it would be a new predicate in Lisp
> implementation. Wold be nice exercise to me to learn how to write
> a tramp handler :-), but I am not sure it is desired.
>
> Don't know, what Michael and Eli have to say about?
I'm in line with Eli here. I have no glaring example that we need COUNT
greater than one. Just a vague idea, that it could help to implement a
more performant file name completion, especially in the remote
case. That is, if you have a very large directory, you let complete file
names on-the-fly (while typing in the minibuffer) with just the first 50
hits from directory-files, which could be retrieved much faster than,
say, more than 2000 file names (this is what I have in /usr/bin). The
complete file names for completion are retrieved, when the user hits TAB.
Just a vague idea; I haven't checked how to implement.
So I propose we still use the COUNT optional argument. This isn't worse
than an argument NOT-EMPTY, which would let directory-files return
immediately after the first hit has found.
Best regards, Michael.
- Re: empty-directory predicate, native implementation, (continued)
- Re: empty-directory predicate, native implementation, Arthur Miller, 2020/10/16
- Re: empty-directory predicate, native implementation, Michael Albinus, 2020/10/17
- Re: empty-directory predicate, native implementation, Arthur Miller, 2020/10/17
- RE: empty-directory predicate, native implementation, Drew Adams, 2020/10/17
- Re: empty-directory predicate, native implementation, Arthur Miller, 2020/10/17
- RE: empty-directory predicate, native implementation, Drew Adams, 2020/10/17
- Re: empty-directory predicate, native implementation, Arthur Miller, 2020/10/17
- Re: empty-directory predicate, native implementation, Arthur Miller, 2020/10/17
- RE: empty-directory predicate, native implementation, Drew Adams, 2020/10/17
- Re: empty-directory predicate, native implementation, Arthur Miller, 2020/10/17
- Re: empty-directory predicate, native implementation,
Michael Albinus <=
- Re: empty-directory predicate, native implementation, Eli Zaretskii, 2020/10/17
- RE: empty-directory predicate, native implementation, Drew Adams, 2020/10/18
- Re: empty-directory predicate, native implementation, Michael Albinus, 2020/10/18
- RE: empty-directory predicate, native implementation, Drew Adams, 2020/10/18
- Re: empty-directory predicate, native implementation, Michael Albinus, 2020/10/18
- Re: empty-directory predicate, native implementation, Stefan Monnier, 2020/10/18
- RE: empty-directory predicate, native implementation, Drew Adams, 2020/10/18
- Re: empty-directory predicate, native implementation, Arthur Miller, 2020/10/18
- Re: empty-directory predicate, native implementation, Arthur Miller, 2020/10/18
- Re: empty-directory predicate, native implementation, Michael Albinus, 2020/10/19