What's the proper way to evaluate a variable having a value?

Asked Dec 10 '18 at 21:20

Active Dec 10 '18 at 21:20

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I have a class of variables that are being assigned None at instantiation. I've manually hardcoded data assignments to some of these variables, and am trying to evaluate whether or not they exist.

So basically I've set my_class.first_col = 4. The instantiation part looks essentially like:

def __init__(self):
  self.first_col = None

When I run this with the manual set to 4: print(my_class.first_col == True) it returns False. What's the proper way to see if that variable is assigned to something other than None?

asked Dec 10 '18 at 21:20

simplycoding

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How about `my_class.first_col is not None` ? – Lasse V. Karlsen Dec 10 '18 at 21:27
Yeah I saw that option per this question after I posted, and it fixed the problem. Still unsure why `first_col == True` doesn't work though. https://stackoverflow.com/questions/3965104/not-none-test-in-python – simplycoding Dec 10 '18 at 21:35
You assigned it the value 4? That's not True. – Lasse V. Karlsen Dec 10 '18 at 21:52
Then what is True? With your comment, I realized I assumed every object or variable was True, but I guess not – simplycoding Dec 11 '18 at 15:30

What's the proper way to evaluate a variable having a value?

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