[Python-Dev] Updates to PEP 471, the os.scandir() proposal

Nick Coghlan ncoghlan at gmail.com
Thu Jul 10 15:58:57 CEST 2014


On 10 Jul 2014 03:39, "Victor Stinner" <victor.stinner at gmail.com> wrote:
>
> 2014-07-10 9:04 GMT+02:00 Paul Moore <p.f.moore at gmail.com>:
> > As someone (Tim?) pointed out later in the thread,
> > FindFirstFile/FindNextFile doesn't follow symlinks by default (and nor
> > do the dirent entries on Unix). So whether or not it's "natural", the
> > "free" functionality provided by the OS is that of lstat, not that of
> > stat. Presumably because it's possible to build symlink-following code
> > on top of non-following code, but not the other way around.
>
> DirEntry methods will remain free (no syscall) for directories and
> regular files. One extra syscall will be needed only for symlinks,
> which are more rare than other file types (for example, you wrote "
> Windows typically makes little use of symlinks").

The info we want for scandir is that of the *link itself*. That makes it
easy to implement things like the "followlinks" flag of os.walk. The *far
end* of the link isn't relevant at this level.

The docs just need to be clear that DirEntry objects always match lstat(),
never stat().

Cheers,
Nick.

>
> See my pseudo-code:
> https://mail.python.org/pipermail/python-dev/2014-July/135439.html
>
> On Windows, _lstat and _stat attributes will be filled directly in the
> constructor on Windows for regular files and directories.
>
> Victor
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