class A:
x=1
def __add__(self, obj):
if isinstance(obj,A):
return self.x+obj.x
return "False"
class B(A):
x=2
a=A()
b=B()
print(a+b)
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John Anderson
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Vedant Bhosale
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2In the `__add__()` method, the `obj` argument is the `b` instance of class `B`. – John Anderson Feb 08 '19 at 03:43
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but while executing a=A() what gets passed into obj arguments? – Vedant Bhosale Feb 08 '19 at 03:46
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1The `__add__` method is not called in `a = A()`. – John Anderson Feb 08 '19 at 03:48
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`The __add__ method is not called in a = A()` - so nothing is passed to the `obj` parameter. – wwii Feb 08 '19 at 04:31
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It isn't clear what your question is. https://docs.python.org/3/library/functions.html#isinstance – wwii Feb 08 '19 at 04:41
1 Answers
0
The add method takes self, the first object in the addition, and another one, other.
For example:
class A:
def __init__(self, x):
self.x=x
def __add__(self, obj):
if isinstance(obj,A):
return self.x+obj.x
raise NotImplementedError
a = A(3)
b = A(4)
res = a + b # this is essentially a.__add__(obj=b)
# self is implicitly the object a
# res == 7
Charles
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how does if isinstance condition gets satisfied as obj is instance of Class B? – Vedant Bhosale Feb 08 '19 at 04:10
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2Well since B is a subclass of A, `isinstance` will still return `True`. Take a look at [this great SO post](https://stackoverflow.com/questions/1549801/what-are-the-differences-between-type-and-isinstance) – Charles Feb 08 '19 at 04:15