Python Variables: Pointers or References?

Rethinking Python Variables: Pointers or References?

In the world of Python programming, variables have often been described as "pointers." However, this raises questions about the behavior of these variables. Consider the following code snippets:

i = 5
j = i
j = 3
print(i)

Based on the "pointer" assumption, it might be expected that i would have a value of 3 after the code runs. However, the actual result is 5.

What's going on?

Understanding Python References

In Python, variables do not act like pointers. Instead, they work as references. A reference connects a variable to an object. When you assign a variable to another variable, you are creating a reference to the same object.

This means that in the first code snippet, i and j are references to the same integer object (int(5)). When the value of j is changed to 3, a new integer object (int(3)) is created and j becomes a reference to it. However, i remains a reference to the original integer object int(5).

The second code snippet illustrates this behavior with a list:

i = [1,2,3]
j = i
i[0] = 5
print(j)

In this case, i and j are both references to the same list object. When i[0] is modified, the list object itself is changed, so both i and j still reference the same list.

Conclusion

Python variables are not pointers, but rather references. They establish connections to objects, and when a variable's value is changed, it affects the object itself. This explains the unexpected results seen in the code snippets and serves as a fundamental concept in understanding Python's variable behavior.

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