[Python-Dev] an alternative to embedding policy in PEP 418 (was: PEP 418: Add monotonic clock)

[Oleg Broytman]

On Wed, Apr 04, 2012 at 12:52:00PM -0700, Ethan Furman wrote:
> Oleg Broytman wrote:
> >On Wed, Apr 04, 2012 at 11:03:02AM -0700, Ethan Furman wrote:
> >>Oleg Broytman wrote:
> >>>  . Pythonic equivalent of "get_clock(THIS) or get_clok(THAT)" is
> >>>
> >>>for flag in (THIS, THAT):
> >>>   try:
> >>>       clock = get_clock(flag)
> >>>   except:
> >>>       pass
> >>>   else:
> >>>       break
> >>>else:
> >>>   raise ValueError('Cannot get clock, tried THIS and THAT')
> >>
> >>Wow -- you'd rather write nine lines of code instead of three?
> >>
> >>clock = get_clock(THIS) or get_clock(THAT)
> >>if clock is None:
> >>    raise ValueError('Cannot get clock, tried THIS and THAT')
> >
> >   Yes - to force people to write the last two lines. Without forcing
> >most programmers will skip them.
> 
> Forced?  I do not use Python to be forced to use one style of
> programming over another.

   Then it's strange you are using Python with its strict syntax
(case-sensitivity, forced indents), ubiquitous exceptions, limited
syntax of lambdas and absence of code blocks (read - forced functions),
etc.

> And it's not like returning None will allow some clock calls to work
> but not others -- as soon as they try to use it, it will raise an
> exception.

   There is a philosophical distinction between EAFP and LBYL. I am
mostly proponent of LBYL.
   Well, I am partially retreat. "Errors should never pass silently.
Unless explicitly silenced." get_clock(FLAG, on_error=None) could return
None.

Oleg.
-- 
     Oleg Broytman            http://phdru.name/            phd at phdru.name
           Programmers don't die, they just GOSUB without RETURN.