What Does Python's `id()` Function Actually Do?

Understanding the Purpose and Usage of id() Function in Python

In the Python documentation, the id() function is described as a means to retrieve an object's "identity," represented as an integer guaranteed to remain unique for the object's lifetime. While this may suggest a similarity to memory addresses in C, it's important to separate the two concepts.

Distinguishing id() from Memory Addresses

Internally, in CPython, the implementation of Python, the id() function returns the object's address in memory. However, it's crucial to recognize that the integer obtained from id() is not directly related to the object's size or data type.

Usage in Practice

Despite its existence, the id() function seldom finds practical application in Python. The recommended approach for checking object identity is through the is operator, which efficiently compares object references.

Special Cases

One noteworthy exception where id() proves useful is in debugging scenarios. When attempting to ascertain whether two seemingly independent objects are actually references to the same underlying object, id() provides a valuable tool for confirmation.

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