testing for valid reference: obj vs. None!=obs vs. obj is not None
Bruno Desthuilliers
bdesth.quelquechose at free.quelquepart.fr
Mon Sep 4 19:46:51 EDT 2006
alf a écrit :
> Hi,
>
> I have a reference to certain objects. What is the most pythonic way to
> test for valid reference:
>
> if obj:
Don't do this:
for o in [0, '', [], {}, ()]:
print obj, bool(obj), obj is None
> if None!=obs:
In python, assignement is a statement, not an expression, so there's no
way you could write 'if obj = None' by mistake (-> syntax error). So
this style is unpythonic. Also, None is a singleton, and identity test
is way faster than equality test.
> if obj is not None:
That's the good one.
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