Re: [libgpiod] [RFC PATCH] bindings: python: allow specifying infinite timeout

[andy.shevchenko@gmail.com]

Tue, May 23, 2023 at 12:06:47PM +0200, Bartosz Golaszewski kirjoitti:
> On Fri, May 19, 2023 at 7:47 PM Nicolas Frattaroli
> <frattaroli.nicolas@gmail.com> wrote:

> > So far, libgpiod's Python bindings had no way to state that a
> > user wishes to wait for events indefinitely, as a timeout of
> > None would intentionally be converted to 0 seconds, i.e. return
> > from the select call in poll_fd immediately.
> >
> > The usual Python convention and even the select convention is
> > to block indefinitely on a timeout=None. However, changing the
> > poll_fd function to do this now would change an (intentional)
> > API design choice by libgpiod 2.0 that API users presumably
> > rely on.
> >
> > By allowing float("inf") (or in fact math.inf, or your favourite
> > other way to get an infinite float) to mean waiting infinitely
> > solves this by extending the API rather than changing it.
> >
> > On gpiod Python bindings without this change, passing inf results
> > in an OverflowError being raised in select. API users who wish to
> > support older versions of the bindings can catch this exception and
> > act on it.

...

> I like this approach too. In fact - it may be even clearer and more
> intuitive than converting None to infinite timeout.

With all respect to the clever design solutions I would rather go the
de facto Pythonic way. If the native libraries use None for indefinite
then it's better to do that way, otherwise we will add quite a confusion
to the Python users.

> Any objections against using negative numbers for the same purpose as well?

The question here is: What in the very same situations are other (presumably
native) Python libraries using?

-- 
With Best Regards,
Andy Shevchenko