[Python-Dev] PEP 418: Add monotonic clock

[Yury Selivanov]

On 2012-03-28, at 11:35 AM, Nick Coghlan wrote:
> So, the primary use case is that we want to replace many of the
> time.time() calls in the standard library with time.monotonic() calls.
> To avoid backwards compatibility problems in the cross-platform
> support, that means time.monotonic() *must be available on every
> platform that currently provides time.time()*.

OK.  I got your point.  And also I've just realized what I dislike about
the way you want to implement the fallback.  The main problem is that
I treat the situation when time jumps backward as an exception, because,
again, if you have timeouts you may get those timeouts to never be 
executed.  So let's make the "try_monotonic()" function (or whatever 
name will be chosen) this way (your original code edited):

  def _make_monotic():
     try:
         # Use underlying system monotonic clock if we can
         return _monotonic
     except NameError:
         _tick = time()
         def monotic():
             nonlocal _time
             _new_tick = time()
             if _new_tick <= _tick:
                 raise RuntimeError('time was adjusted backward')
             _tick = _new_tick
             return _new_tick

         return monotonic

  try_monotonic = _make_monotonic()  

At least this approach tries to follow some of the python's zen.

-
Yury