Re: Timestamp of installed files

On Sat, 4 Aug 2018 at 09:18, Chris Jerdonek <[email protected]> wrote:
>
> On Sat, Aug 4, 2018 at 1:08 AM, Paul Moore <[email protected]> wrote:
> > On Sat, 4 Aug 2018 at 08:35, Jeroen Demeyer <[email protected]> wrote:
> >
> >> So both are different issues, and I agree with both: during the source
> >> extraction and build process, you want to preserve timestamps as much as
> >> possible. But for the installation, you do NOT want to preserve timestamps.
> >
> > If this is about the distutils install command, it's worth noting that
> > pip is moving to a situation where we'll never use the
> > distutils/setuptools "install" command, bur rather we'll build wheels
> > and install from wheel. The new PEP 517 installation code will use
> > that route exclusively (there's not even a provision in PEP 517 for
> > direct installs from source). So the behaviour of the "setup.py
> > install" command won't affect pip installs at all in the longer term.
> > (How long, I don't know - it depends on how soon we feel we can switch
> > fully to PEP 517, and it's a bit premature to decide on that, as the
> > PEP 517 code isn't even released yet!)
>
> How is the new pip code path slated to behave with respect to Jeroen's
> question / preference? Is it already specified or does it fall out of
> the behavior of existing components, or is it still TBD?

For files extracted from wheels, this is the subject of
https://github.com/pypa/pip/issues/5648, as noted earlier in the
thread by Jeroen (and the commenters on that issue seem to favour
preserving timestamps - Jeroen seemed to say he agreed with this, but
I'm not sure I see how that matches his stated requirement for
installs to not preserve timestamps...). Whether timestamps are
preserved by the wheel building process depends on the build system -
so the question boils down to "does setup.py bdist_wheel preserve
timestamps?" in the case of the setuptools backend - which is really a
question for the wheel project. In the more general case, you'd have
to ask the same question of flit, and any other backends you cared
about.

So:

  * wheel -> installed: Currently under discussion, with (as far as I
can see) conflicting preferences. From the comments in issue 5648 it
seems like pip currently alters timestamps, but the commenters there
think it would be a "rather uncontroversial patch"
(https://github.com/pypa/pip/issues/5648#issuecomment-408439568) to
change that
  * source -> wheel: the backend's responsibility

Personally, I have no opinion on the matter.

Paul
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