How can we get the default behavior of __repr__()?

Question

If someone writes a class in python, and fails to specify their own __repr__() method, then a default one is provided for them. However, suppose we want to write a function which has the same, or similar, behavior to the default __repr__(). However, we want this function to have the behavior of the default __repr__() method even if the actual __repr__() for the class was overloaded. That is, suppose we want to write a function which has the same behavior as a default __repr__() regardless of whether someone overloaded the __repr__() method or not. How might we do it?

class DemoClass:
    def __init__(self):
        self.var = 4
    def __repr__(self):
        return str(self.var)

def true_repr(x):
    # [magic happens here]
    s = "I'm not implemented yet"
    return s

obj = DemoClass()

print(obj.__repr__())

print(true_repr(obj))

Desired Output:

print(obj.__repr__()) prints 4, but print(true_repr(obj)) prints something like:
<__main__.DemoClass object at 0x0000000009F26588>

Answer 1

You can use object.__repr__(obj). This works because the default repr behavior is defined in object.__repr__.

Answer 2

Note, the best answer is probably just to use object.__repr__ directly, as the others have pointed out. But one could implement that same functionality roughly as:

>>> def true_repr(x):
...     type_ = type(x)
...     module = type_.__module__
...     qualname = type_.__qualname__
...     return f"<{module}.{qualname} object at {hex(id(x))}>"
...

So....

>>> A()
hahahahaha
>>> true_repr(A())
'<__main__.A object at 0x106549208>'
>>>