Learn how to use Python's := walrus operator to simplify conditions, avoid redundant calls, and write cleaner, more efficient code in Python 3.8+.
Introduced in Python 3.8, the Walrus Operator (:=) is a syntactic addition that enables — the ability to assign values to variables as part of an expression.
While it may look unusual at first glance, the walrus operator brings clarity and efficiency to certain programming constructs by reducing redundancy and improving performance in specific use cases. In this post, we’ll explore what it is, why it was introduced, and how you can use it effectively.
The walrus operator allows assignment inside expressions. Traditionally, Python required assignments to be made in statements — you couldn’t assign a value within an expression like an if or while condition. The walrus operator changes that.
Syntax:
It returns the value of the expression while also assigning it to the variable.
Before:
With Walrus:
Before:
With Walrus:
This pattern is especially clean and idiomatic with the walrus operator.
Suppose you’re filtering based on a computed value:
Before:
With Walrus:
Stick to cases where it clearly improves code clarity and removes duplication.
Before:
With Walrus:
This not only saves a line of code but also ensures the function is only called once, critical when the function is expensive or has side effects.
The walrus operator is not about writing shorter code, it’s about writing clearer and more efficient code when used appropriately. It's particularly useful in loops, comprehensions, and conditions where eliminating redundancy improves both performance and readability.
Like any powerful feature, it’s best used with intention, sparingly and where it genuinely improves your code.
The walrus operator is available only from Python 3.8+. Attempting to use it in earlier versions will result in a syntax error.
Let your code smile like a walrus, efficiently and elegantly.
The walrus operator, introduced in Python 3.8, allows assignment within expressions. It enables assigning a value to a variable as part of an expression, such as within if or while conditions, improving both clarity and performance in many scenarios.
Use it when:
Avoid it in deeply nested expressions where it might hurt readability.
No. The walrus operator cannot be used at the top level of a statement like x := 5. That would raise a syntax error. It's designed strictly for inline assignments within expressions, not as a general-purpose replacement for =.
It avoids repeating expensive or side-effect-prone operations, such as calling a function multiple times. It also enables concise expression of logic, especially in while loops and list comprehensions, by embedding assignments directly in conditionals or filters.
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variable := expressionfetch = fetch_user_from_db(user_id)
if fetch["active"]:
log_user_activity(fetch_user_from_db(user_id)) # Called againif (user := fetch_user_from_db(user_id)):
if user["active"]:
log_user_activity(user) # Only one callline = input()
while line != "exit":
print(f"You said: {line}")
line = input()while (line := input()) != "exit":
print(f"You said: {line}")results = []
for line in lines:
val = parse(line)
if val > 0:
results.append(val)results = [val for line in lines if (val := parse(line)) > 0](x := 5) = y # ❌ SyntaxErrorx = (y := 10) # Valid, but unnecessary. Just use y = 10; x = yresult = expensive_lookup()
if result:
use(result)if (result := expensive_lookup()):
use(result)
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