如何简化这种Python代码？

Question

我有很多这样的代码块:

try:
  a = get_a()
  try:
    b = get_b()

    # varying codes here, where a and b are used

  finally:
    if b:
      cleanup(b)
finally:
  if a:
    cleanup(a)

我希望写一些像这样的魔术代码:

some_magic:
  # varying codes here, where a and b are also available

这可能吗？

Answer 1

如果您不能或不想为a和实现上下文协议b,则可以使用contextlib工具创建上下文:

from contextlib import contextmanager

@contextmanager
def managed(a):
    try:
        yield a
    finally:
        if a:
            cleanup(a)

with managed(get_a()) as a, managed(get_b()) as b:
    # do something here
    pass