Augmented Assignment (Sets)

00:00 Let’s take a deep dive into how augmented assignment actually works. You saw that many of the modifying set methods have a corresponding augmented assignment.

00:09 Like we saw, intersection update (&=), and difference update (-=), and symmetric difference update (^=). These are not the same as their expanded out counterparts.

00:19 For example, x &= {1} is not the same as x = x & {1}.

00:29 Here’s an example where you will see that. Here we have x = {1}, y = x. That will make y point to the same set that x is pointing to.

00:41 Now we will use update (|=) to update x with {2}.

00:47 Here, x becomes {1, 2} and y also becomes {1, 2} because they are pointing to the same object. Versus x = {1}, y = x, x = x | {2}. x will become {1, 2}, but y will become nothing.

01:08 It will actually be the original {1}. This is because x = x | {2} created a new set of {1, 2} and then bound that back to x. y still pointed to the original {1}.

01:25 The first example mutates x, the second example reassigns x.