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

[Ben Hoyt]

>> 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().

Yeah, I agree with this. It makes the function (and documentation and
implementation) quite a lot simpler to understand.

scandir() is a lowish-level function which deals with the directory
entries themselves, and mirrors both Windows FindNextFile and POSIX
readdir() in that. If the user wants follow-links behaviour, they can
easily call os.stat() themselves. If this is clearly documented that
seems much simpler to me (and it also seems implicit to me in the fact
that you're calling is_dir() on the *entry*).

Otherwise we might as well go down the route of -- the objects
returned are just like pathlib.Path(), but with stat() and lstat()
cached on first use.

-Ben