CODEWITHSUNDEEP
pythonobjectmagic-methods
Torilla
Torilla

Reputation: 403

Python Object should pretend to be None or empty

I have a python class that has certain values. This class is just a wrapper class that is used as a datacontainer inside another class object.

When I have any variable in python, I can check if it is empty (or for that matter equal to False) by simply doing

my_variable = "something" 
if my_variable
>>> True

my_variable = None # or False, or 0 or whatever equals False
if my_variable
>>> False

So far this is all as usual. But I'd like to behave my class exactly the same but only if a certain attribute has a certain value, otherwise it should return True. Is this possible or does python only check if my_variable is bound to something or not?

class Test(object):
    def __init__(self, isTrue):
        self.isTrue = isTrue

A = Test(True)
B = Test(False)

if A
>>> True

if B
>>> False

Upvotes: 0

Views: 238

Answers (1)

0x5453
0x5453

Reputation: 13589

Sounds like you are looking for __bool__ (or __nonzero__ for Python 2).

class Test(object):
    def __init__(self, isTrue):
        self.isTrue = isTrue
    def __bool__(self):
        return self.isTrue

Upvotes: 3

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