[Distutils] Module Installation Issues

[Paul Moore]

On 13 September 2016 at 23:55, Donald Stufft <donald at stufft.io> wrote:
> The 90% case works when it’s *only* pure python and there’s no upgrading/downgrading involved, however you can’t control whether there are going to be upgrades/downgrades or not when dependencies are in play because of ==, >=, >, <, <=, etc.

I would be OK with an invocation that only ever installed and never
did an upgrade, as that would avoid the worst situations. Of course,
(a) AFAIK pip doesn't have such a method (other than --no-deps) at the
moment (dependencies are always upgraded if needed) and (b) there is
an ongoing proposal to change "pip install" to always upgrade, and
this is the exactly the opposite of what we'd need from the Python
prompt.

I understood Steve's proposal to be that we detect cases which do an
upgrade rather than a pure install, and in that case report "you
should restart your Python session". That's a common[1] pattern on
Windows, so should be familiar to Windows users, who I suspect are
more likely to hit this issue.

Paul

[1] Common, but not particularly loved - it's the source of the jokes
about "your mouse has moved, do you want to restart Windows for this
change to take effect?"