[Python-Dev] PEP 471 -- os.scandir() function -- a better and faster directory iterator

Devin Jeanpierre jeanpierreda at gmail.com
Tue Jul 1 04:17:00 CEST 2014

The proposal I was replying to was that:

- There is no .refresh()
- ensure_lstat=False means no OS has populated attributes
- ensure_lstat=True means ever OS has populated attributes

Even if we add a .refresh(), the latter two items mean that you can't
avoid doing extra work (either too much on windows, or too much on
linux), if you want only a subset of the files' lstat info.

-- Devin

P.S. your mail client's quoting breaks my mail client (gmail)'s quoting.

On Mon, Jun 30, 2014 at 7:04 PM, Glenn Linderman <v+python at g.nevcal.com> wrote:
> On 6/30/2014 4:25 PM, Devin Jeanpierre wrote:
> On Mon, Jun 30, 2014 at 3:07 PM, Tim Delaney
> <timothy.c.delaney at gmail.com> wrote:
> On 1 July 2014 03:05, Ben Hoyt <benhoyt at gmail.com> wrote:
> So, here's my alternative proposal: add an "ensure_lstat" flag to
> scandir() itself, and don't have *any* methods on DirEntry, only
> attributes.
> ...
> Most importantly, *regardless of platform*, the cached stat result (if
> not None) would reflect the state of the entry at the time the
> directory was scanned, rather than at some arbitrary later point in
> time when lstat() was first called on the DirEntry object.
> I'm torn between whether I'd prefer the stat fields to be populated on
> Windows if ensure_lstat=False or not. There are good arguments each way, but
> overall I'm inclining towards having it consistent with POSIX - don't
> populate them unless ensure_lstat=True.
> +0 for stat fields to be None on all platforms unless ensure_lstat=True.
> This won't work well if lstat info is only needed for some entries. Is
> that a common use-case? It was mentioned earlier in the thread.
> If it is, use ensure_lstat=False, and use the proposed (by me) .refresh()
> API to update the data for those that need it.
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