How Does Python Handle Object Passing in Functions: Value or Reference?

Understanding Reference Passing in Python

When working with collections like lists and arrays in Python, developers often wonder whether these objects are passed by value or by reference. Contrary to the original title, "Passing values in Python", this distinction plays a crucial role in how these variables are handled within functions.

In Python, objects are passed by reference, meaning that a reference to the actual object is assigned to the parameter in the function. This differs from pass-by-value, where a copy of the object is created and passed. As a result, any changes made to the collection within the function also reflect in the original collection outside the function.

This reference passing behavior applies to both mutable and immutable objects. Immutable objects, such as strings, tuples, and integers, cannot be modified directly within the function. However, altering a mutable object, such as a list or dictionary, within the function does update the original object outside.

Understanding mutable and immutable objects is crucial in comprehending reference passing. Immutable objects always maintain their original value and create a new instance when altered. On the other hand, mutable objects allow for in-place changes, resulting in modifications to the original object.

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