从自定义操作捕获ArgumentTypeError异常

问题描述

从我自己的自定义操作中抛出ArgumentTypeError异常的最佳做法是什么，让argparse为我抓住它？

What is the best practice to throw an ArgumentTypeError exception from my own custom action and let the argparse to catch it for me?

似乎argparse的try / except块对我的自定义操作不处理此异常。虽然这样做对于内置的动作来说也是如此。

It seems that argparse's try/except block does not handle this exception for my custom actions. Though it does that just fine for its built-in actions.

class unique_server_endpoints(argparse.Action):
    """This class avoids having two duplicate OuterIPs in the client argument list"""
    def __call__(self, parser, namespace, values, option_string=None):
        ips = set()
        endpoints = []
        for r in values:
            ep = server_endpoint(r)
            if ep[0] in ips:
                raise argparse.ArgumentTypeError("Duplicate OuterIPs found")
            else:
                ips.add(ep[0])
                endpoints.append(ep)
        setattr(namespace, self.dest, endpoints)

和

group.add_argument('-c', "--client", nargs = 2,
            dest = "servers", action = unique_server_endpoints,

例如，在上面的代码中如果我会有重复的IP，那么异常会f全部到主要功能，并打印丑陋的堆栈跟踪。我不想要这个，我也不想在 main 中放入try / except块。

For example, in the code above If I would have duplicate IPs then the exception would fall down to the main function and print the ugly stacktrace. I don't want that and neither I don't want to put a try/except block inside main.

推荐答案

查看argparse源代码后，我发现它将ArgumentTypeError转换为ArgumentError异常。

After looking at argparse source code I figured out that it translates ArgumentTypeError to ArgumentError exception.

所以而不是：

            raise argparse.ArgumentTypeError("Duplicate OuterIPs found")

我应该有：

            raise argparse.ArgumentError(self, "Duplicate OuterIPs found")

和argparse仍然会为我做其他事情（捕获异常和打印使用消息）...

And argparse would still do the rest for me (catch exception and print usage message) ...

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