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

[Victor Stinner]

Hi,

2014-07-08 15:52 GMT+02:00 Ben Hoyt <benhoyt at gmail.com>:
> After some very good python-dev feedback on my first version of PEP
> 471, I've updated the PEP to clarify a few things and added various
> "Rejected ideas" subsections. Here's a link to the new version (I've
> also copied the full text below):

Thanks, the new PEP looks better.

> * Removed the "open issues" section, as the three open issues have
> either been included (full_name) or rejected (windows_wildcard)

I remember a pending question on python-dev:

- Martin von Loewis asked if the scandir generator would have send()
and close() methods as any Python generator. I didn't see a reply on
the mailing (nor in the PEP).

> One known error in the PEP is that the "Notes" sections should be
> top-level sections, not be subheadings of "Examples". If someone would
> like to give me ("benhoyt") commit access to the peps repo, I can fix
> this and any other issues that come up.

Or just send me your new PEP ;-)

> Notes on caching
> ----------------
>
> The ``DirEntry`` objects are relatively dumb -- the ``name`` and
> ``full_name`` attributes are obviously always cached, and the ``is_X``
> and ``lstat`` methods cache their values (immediately on Windows via
> ``FindNextFile``, and on first use on POSIX systems via a ``stat``
> call) and never refetch from the system.

It is not clear to me which methods share the cache.

On UNIX, is_dir() and is_file() call os.stat(); whereas lstat() and
is_symlink() call os.lstat().

If os.stat() says that the file is not a symlink, I guess that you can
use os.stat() result for lstat() and is_symlink() methods?

In the worst case, if the path is a symlink, would it be possible that
os.stat() and os.lstat() become "inconsistent" if the symlink is
modified between the two calls? If yes, I don't think that it's an
issue, it's just good to know it.

For symlinks, readdir() returns the status of the linked file or of the symlink?

Victor