class CtxMgr: def __init__(self, id): self.id = id def __enter__(self): print("__enter__", self.id) return self def __exit__(self, a, b, c): print("__exit__", self.id, repr(a), repr(b)) # simple case def foo(): with CtxMgr(1): return 4 print(foo()) # for loop within with (iterator needs removing upon return) def f(): with CtxMgr(1): for i in [1, 2]: return i print(f()) # multiple for loops within with def f(): with CtxMgr(1): for i in [1, 2]: for j in [3, 4]: return (i, j) print(f()) # multiple for loops within nested with's def f(): with CtxMgr(1): for i in [1, 2]: for j in [3, 4]: with CtxMgr(2): for k in [5, 6]: for l in [7, 8]: return (i, j, k, l) print(f()) # multiple for loops that are optimised, and nested with's def f(): with CtxMgr(1): for i in range(1, 3): for j in range(3, 5): with CtxMgr(2): for k in range(5, 7): for l in range(7, 9): return (i, j, k, l) print(f())