When Is Self Statement True And When Is False?

Can someone explain this if self.cards condition? When will it be True and when will it be False? def __init__(self): self.cards = [] def __str__(self): if self.cards:

Solution 1:

First, you should probably show us when self.cards is used for the first time.
Assuming it is some sort of a container(list, set or dict) it will be true if there are elements in it and false if it is empty.

Solution 2:

Any object can be tested for truth value in Python. The following values are considered false:

None

False

zero of any numeric type, for example, 0, 0L, 0.0, 0j.

any empty sequence, for example, '', (), [].

any empty mapping, for example, {}.

instances of user-defined classes, if the class defines a __nonzero__() or __len__() method, when that method returns the integer zero or bool value False.

All other values are considered true — so objects of many types are always true.

In this case cards is False when it is empty because it is a list. When the object is created, __init__() creates the cards empty list, so that if statement's condition is always False when the object is created.