Python equivalent of golang’s defer statement

To emulate defer fmt.Println(*a, i) example, you could use contextlib.ExitStack:

#!/usr/bin/env python3
from contextlib import ExitStack
from functools import partial

print("counting")
with ExitStack() as stack:
    for i in range(10):
        a = i
        stack.callback(partial(print, a, i))

    x = 42
    a = x
    print("done")

Output

counting
done
9 9
8 8
7 7
6 6
5 5
4 4
3 3
2 2
1 1
0 0

It is easy to emulate the mutex case:

def some_function(lock=Lock()):
    with lock:
        # whatever