python - Overloading operators on the fly

user_13438431 0
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I would like to know, if there is a way to overload operators in Python in runtime. For instance:

class A:
   pass
a = A()
a.__str__ = lambda self: "noice"
print(str(a))

The desired output is "noice", but the given code uses object's implementation of the str function instead, yielding something along the lines: <__main__.A object at 0x000001CAB2051490>.

Why doesn't the code use my overriden implementation of the function overload?

Python version used is 3.9.2.

overloading overriding operator-overloading python
2 Answers

When you call str(a), it resolves to the equivalent of a.__class__.__str__(a), not a.__str__().

>>> A.__str__ = lambda self: "noice"
>>> str(a)
'noice'
user_37997590

You have to assign that function to the class, not an instance of the class.

>>> class A:
...     pass
...
>>> a = A()
>>> a.__str__ = lambda x: 'hi'
>>> print(a)
<__main__.A object at 0x000000A4D16C1D30>
>>> A.__str__ = lambda x: 'hi'
>>> print(a)
hi
user_26170680
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