Question

I have some code like this:

if var:
    if var2 == getSomeValue()

This could be in a single expression.

if var and var2 == getSomeValue():

…but getSomeValue() can only be called if var is True.

So, when calling if var and var2 == getSomeValue(), are both evaluated by the interpreter, or the evaluation stops at var if False? Where I can find this information on python documentation? (I didn’t know what to search…:/ )

Answer 1

This is called short-circuiting, and Python does it, so you’re good.

UPDATE: Here’s a quick example.

>>> def foo():
...     print "Yay!"
... 
>>> if True and foo() is None:
...     print "indeed"
... 
Yay!
indeed
>>> if False and foo() is None:
...     print "nope"
... 

UPDATE 2: Putting the relevant PEP (308) in my answer so it doesn’t get overlooked in the excellent comment from @Somebody still uses you MS-DOS.