Question

I would expect an empty list to value test as False, but I’m a bit confused why a reference for a list containing an object reports as False also when value tested as in the following example:

>>> weapon = []
>>> weapon == True
False
>>> weapon.append("sword")
>>> weapon == True
False
>>> weapon
['sword']

If weapon = [] is False, why would weapon = ['sword'] also be False? According to docs http://docs.python.org/release/2.4.4/lib/truth.html, it should be True. What am I missing in my understanding of this?

Answer 1

You need to use bool() if you want to compare it directly

>>> weapon = []
>>> bool(weapon) == True
False
>>> weapon.append("sword")
>>> bool(weapon) == True
True

When you test a condition using if or while, the conversion to bool is done implicitly

>>> if weapon == True:  # weapon isn't equal to True
...     print "True"
... 
>>> if weapon:
...     print "True"
... 
True