Peter Otten writes:
> Jussi Piitulainen wrote:
>
> > Thibault Langlois writes:
> >
> >> Hello,
> >>
> >> $ python
> >> Python 2.7.4 (default, Sep 26 2013, 03:20:26)
> >> [GCC 4.7.3] on linux2
> >> Type "help", "copyright", "credits" or "license" for more information.
> >> >>> 1 > 0 == True
> >> False
> >> >>> (1 > 0) == True
> >> True
> >> >>> 1 > (0 == True)
> >> True
> >> >>>
> >>
> >> What am I missing here ?
> >
> > One or both of the following:
> >
> > >>> 0 == True
> > False
> > >>> True and False
> > False
> > >>> 1 > 0
> > True
> >
> > Or the fact that (1 > 0 == True) means ((1 > 0) and (0 == True)),
> > where each expression in such a chain is evaluated once, though in
> > this case it really does not matter since 0 is a literal.
> >
> > Hm, I don't know if the evaluation short-circuits. I think not, but
> > I've never needed to know, and I don't need to know now.
>
> It is easy to check though:
>
> >>> def zero():
> ... print("zero")
> ... return 0
> ...
> >>> def one():
> ... print("one")
> ... return 1
> ...
> >>> def true():
> ... print("true")
> ... return True
> ...
> >>> one() > zero() == true()
> one
> zero
> true
> False
> >>> zero() > one() == true()
> zero
> one
> False
>
> So yes, evaluation does short-curcuit.
Now I'm experiencing a mild form of information overload. Thanks
anyway :) My guess was wrong.
Now that I think of it, I've implemented a parser and evaluator once
with this kind of chaining, and it may well have short-circuited.
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