python - 如何从with语句返回？

Question

我有一个函数，它尝试一些参数列表来连接到 ftp 并连接到它可以连接到的第一个服务器。

def connect(params):
    for user, passw, host in params:
        try:
            import pdb;pdb.set_trace()
            with FTPHost(host, user, passw) as h:
                return h
        except FTPError as e:
            logger.debug("Can't connect to ftp error is {}".format(e))
    else:
        raise Exception(
            "Can't connect to ftp server with none of the {}".format(params)
        )

在代码中我正在尝试类似的事情

host = connect(*args)
host.walk()

但返回后连接立即关闭。我想这可能就是它应该如何工作，尽管我希望它不会。但现在我真的不知道如何正确封装应用程序逻辑中的连接尝试。

我的意思是我当然可以将其更改为连续传递样式(这是正确的名称，对吧？)

def connect(params, some_application_function):
    for user, passw, host in params:
        try:
            import pdb;pdb.set_trace()
            with FTPHost(host, user, passw) as host:
                some_application_function(host)
        except FTPError as e:
            logger.debug("Can't connect to ftp error is {}".format(e))
    else:
        raise Exception(
            "Can't connect to ftp server with none of the {}".format(params)
        )

但这似乎不太可读。还有其他选择吗？

Answer 1

也许可以将 with 语句移到 connect 函数之外？

def connect(params):
    for user, passw, host in params:
        try:
            import pdb;pdb.set_trace()
            return FTPHost(host, user, passw)
        except FTPError as e:
            logger.debug("Can't connect to ftp error is {}".format(e))
    else:
        raise Exception(
            "Can't connect to ftp server with none of the {}".format(params)
        )

def main():
    with connect(params) as h:
        do_something(h)