What is a null coalescing operator?

The assignment expression operator (:=), also known as the "walrus operator," allows assigning a value to a variable within an expression. This can make code more concise and readable in certain cases.

# Example of using the walrus operator
# Instead of calculating and assigning first,
# then using in a condition
# count = len(my_list)
# if count > 10:
#     print(f"List is too long: {count} elements")

# Using the walrus operator for more compact code
if (count := len(my_list)) > 10:
    print(f"List is too long: {count} elements")

# Another example in a list comprehension
items = [1, 2, 3, 4, 5]
# Creating a list of squares, but only for those greater than 10
expensive_items = [
    (cost := item * item) for item in items if cost > 10
]

Main advantages:

• Code reduction: Allows avoiding repeated calculation of the same value.
• Improved readability (in some cases): When assignment and usage of a value happen close together, it can make the logic clearer.

It is important to use it wisely so as not to impair code readability. It is not intended to replace all standard assignments.