Python's documentation states that one has to use is operator co compare a variable with None. What happens when you avoid that advice?
Consider a class:
Next, the usage of the class is:
The confusing thing is that doSomething() is actually called! And that's because len(q) == 0!
The conclusion:
1 2 3 4 5 6
class Queue(object): def __init__(self): self._len = 0 def __len__(self): return self._len
Next, the usage of the class is:
1 2 3 4 5
q = Queue() # at this point, you want to check if q is None if not q: doSomething()
The confusing thing is that doSomething() is actually called! And that's because len(q) == 0!
The conclusion:
1 2
if q is None: doSomething()
