Python中的with语句

class Test:
    def __init__(self):
        self.a = 123
        self.b = 456

    def __enter__(self):
        print('enter...')
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        print('exit...')
        return False


if __name__ == '__main__':
    with Test() as t:
        print(t.a)
        print(t.b)

运行结果

enter...
123
456
exit...