Are Python Variables Pointers or Direct References?

Are Python Variables Pointers? A Clarification

In Python, the concept of variables as pointers often leads to confusion. While it is true that variables share similarities with pointers, there are fundamental differences that need to be addressed.

Immutable Data Types and References

In the example you provided:

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

The expected result of 3 is incorrect because Python treats basic data types like integers as immutable objects. When assigning a new value to a variable, a new object is created, and the variable is bound to the new object. In this case, i remains bound to the original integer with a value of 5, even though j is reassigned to a new integer with a value of 3.

Mutable Data Types and References

On the other hand, when dealing with mutable data types like lists, the situation changes:

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

In this case, both i and j are bound to the same list object. When modifying the list using i[0] = 5, the changes are reflected in both i and j. This behavior is due to the fact that mutable data types like lists are passed by reference, meaning that both i and j hold references to the same shared object in memory.

Conclusion

Python variables are not simply pointers. For immutable data types, they provide direct access to the object itself. For mutable data types, they act as references that allow multiple variables to access and modify the same underlying object. This distinction ensures both performance and flexibility in Python programming.

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