The Python Apprentice

Binding new objects in a function

Let's look at another instructive example. First, we'll create a new list f:

>>> f = [14, 23, 37]

Then we'll create new a function replace(). As the name suggests, rather than modifying its arguments replace() will change the object that its parameter refers to:

>>> def replace(g):...     g = [17, 28, 45]...     print("g =", g)...

We now call replace() with actual argument f:

>>> replace(f)g = [17, 28, 45]

This is much as we'd expect. But what's the value of the external reference f now?

>>> f[14, 23, 37]

The object reference f still refers to the original, unmodified list. This time, the function did not modify the object that was passed in. What's going on?

The answer is this: The object reference f was assigned ...