The Python Walrus

Python evolves over time. Mostly for the good as it adds features that make things easier and more sensible. One of those is the assignment expression. If you have a C background, you are used to assignment expressions. In C, x = 10 both assigns the value 10 to x and also returns the value 10 so you can use it in logical expressions and the like.

In Python, this is not the case. In Python, x = 10 assigns 10 to x but does not have a value that you can use in further expressions. The new assignment expression, :=, works like the C assignment. This means you can write code like:

while i := input("Enter your name: "):
    print(f"You name is {i}")

instead of:

while True:
    i = input("Enter your name: ")
    if i:
        print(f"Your name is {i}")
    else:
        break

I don’t know about you, but I find the code using the walrus operator to be much more clear.

This was not without controversy but in my opinion, this change is a good one. It has some concrete coding advantages and gets Python closer to other mainstream languages. PEP 572 has some examples and discussion that is worth reading.