[Tutor] evaluating AND

[Kent Johnson]

Orest Kozyar wrote:
> Given a variable x that can either be None or a tuple of two floats [i.e.
> (0.32, 4.2)], which syntax is considered most appropriate under Python
> coding standards?
> 
> if x and x[0] > 0:
> 	pass
> 
> =====OR=====
> 
> if x:
> 	if x[0] > 0:
> 		pass

The first is fine.

> In the first, I'm obviously making the assumption that if the first
> condition evaluates to false, then the second condition won't be evaluated.
> But, is this a good/valid assumption to make?

Yes, this is guaranteed by the language.
http://docs.python.org/ref/Booleans.html

Kent