Lambda with different expression returns same output [duplicate]

Question

Take this code snippet for example:

a = []
for x in range(2):
    a.append(lambda: print(x))
print(a[0](), a[1]())

The output is:

1 1

But I expected it to be

0 1

How do I fix this?

Answer 1

Use default arguments:

a = []
for x in range(2):
    a.append(lambda x = x: print(x))
print(a[0](), a[1]())

This works because the default value is evaluated when the function is created. Otherwise all lambda functions will point to the last value of x, which was 1.