Ternary & Walrus Operator

Ternary basics

A ternary is a short if/else expression.

python
score = 85
status = "pass" if score >= 60 else "fail"

This is great when the logic is simple and fits on one line.

Default values with a ternary

python
name = input().strip()
label = name if name else "Anonymous"

Chained ternary (use carefully)

You can chain ternaries, but it can become hard to read.

python
grade = "A" if score >= 90 else "B" if score >= 80 else "C"

If it feels confusing, use a normal if/elif/else block.

Walrus operator basics

The walrus operator := assigns a value inside an expression. It is available in Python 3.8+.

python
if (n := len("python")) > 3:
    print(n)

Walrus in loops

It can help when you read input until the user stops.

python
while (line := input()):
    print("Read:", line)

Common mistakes to avoid

• Using a ternary for complex logic.
• Overusing chained ternaries.
• Using the walrus operator when it makes the code less clear.

What you should understand after this lesson

• How to write a ternary expression.
• When a ternary is helpful and when it is not.
• How to use the walrus operator safely.