Can Python Variable IDs Be Reversed to Dereference Their Original Objects?

Can Variable IDs Be Dereferenced in Python?

It is worth exploring whether variable IDs retrieved using the id function in Python can be dereferenced. Consider the following query:

dereference(id(a)) == a

While there are more practical approaches for achieving this, we will delve into this from an academic perspective.

Answer

A utility function can be employed that is compatible with both Python 2 and Python 3. However, it is important to note that the function's safety is debated, and some experts strongly advise against its use.

import _ctypes

def di(obj_id):
    """ Inverse of id() function. """
    return _ctypes.PyObj_FromPtr(obj_id)

if __name__ == '__main__':
    a = 42
    b = 'answer'
    print(di(id(a)))  # -> 42
    print(di(id(b)))  # -> answer

This function reverses the id() operation, allowing the retrieval of the original object from its variable ID.

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