CODEWITHSUNDEEP
pythonpython-3.8
Anya Precious
Anya Precious

Reputation: 134

Assignment expression scoping in list comprehension problem

I ran into a problem when trying to solve a problem I saw on stackoverflow. link

Here's my code:

def fizz_buzz(n):
    return ['fizzbuzz' if (f:=i%2==0) and (b:=i%5==0) else 'fizz' if f else 'buzz' if b else i for i in range(n)]
print(fizz_buzz(70))

The above code works perfectly but when I try to add a start value to the range() function I get an error the free variable 'b' referenced before assignment.

I don't understand why this is happening

Upvotes: 0

Views: 55

Answers (2)

itismoej
itismoej

Reputation: 1847

User user2357112 is right.

Your condition:

(f:=i%2==0) and (b:=i%5==0)

only assigns b if f is True, but you try to use b anyway.

I want to add some explanation about that.

It is OK when you start from 0 because the f is True at first (0%2==0), so b is computed for the next iterations in the forloop; But if you start from 1, it is not.

For example if you try with range(2, n), it works fine.

Upvotes: 1

user2357112
user2357112

Reputation: 281476

Your condition:

(f:=i%2==0) and (b:=i%5==0)

only assigns b if f is true, but you try to use b anyway.

Upvotes: 2

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