compat.py 文件源码

def nested(*managers):
        exits = []
        vars = []
        exc = (None, None, None)
        try:
            for mgr in managers:
                exit = mgr.__exit__
                enter = mgr.__enter__
                vars.append(enter())
                exits.append(exit)
            yield vars
        except:
            exc = sys.exc_info()
        finally:
            while exits:
                exit = exits.pop()
                try:
                    if exit(*exc):
                        exc = (None, None, None)
                except:
                    exc = sys.exc_info()
            if exc != (None, None, None):
                reraise(exc[0], exc[1], exc[2])