[Python-3000] PEP 3108 - stdlib reorg/cleanup

[Alex Martelli]

On Tue, Apr 29, 2008 at 5:01 AM, Thomas Wouters <thomas at python.org> wrote:
   ...
> > >  * sched
> > >
> > >   + Replaced by threading.Timer.
> >
> > I don't see sched as obsoleted by threading.Timer.  It's much simpler
> > to use (no need for locking) and more efficient (no legions of
> > sleeping threads).  Instead, maybe it should be removed because it's
> > trivial to reimplement as well as being overshadowed by all the other
> > event loops built into bigger systems (tk, qt, gtk, twisted, etc)?
>
> More importantly, sched doesn't use threads, so replacing it with
> threading.Timer is inappropriate :) But yes, it should just go.

Oops, sorry for the duplicate subthread -- I had mailed my objections
to sched removal privately to Brett first (trying to avoid the thread
explosion he feared) and I thought I had later mailed the whole list
but hadn't, so I hit send again first thing this morning.

Anyway, I disagree that sched should go away from the Python standard
library. It's not trivial to reimplement it _properly_, it's a great
way to code a pure-Python cron-substitute that works across all
platforms including very limited (e.g. embedded) ones w/o threads and
with scarce memory (without the overhead of the bigger systems, which
may or may not be well supported on a given limited platform), AND
it's an excellent way to do _simulations_ -- I use it regularly for
both pure simulations AND for systems that, in production, run on a
real timeline, and can also be easily "simulation-tested" by feeding
sched with functions that read the simulated timeline (instead of
time.time and time.sleep). Please let's keep it!


Alex