Argparse: add method for retrieving the parsers of actions

Feature or enhancement

Proposal:

I have a CLI interface with an argparse.ArgumentParser composed of a bunch of different actions. I was trying to validate if an argument had been set to a default value, and with just the main parser available, I was having some issues using get_default() working from the main parser, rather than the parsers for the various actions.

I ended up going with the following comparison, in order to reduce the amount of refactoring I would need to do, where args is the var holding the object returned from parse_args():

        args.my_param == parser._actions[1].choices[args.action]].get_default(args.my_param)

I could also have solved this by adding a wrapper class holding all the subparsers in an object of some kind.

But - I think it would be nice to have a public method for accessing these action parsers, mostly for enabling this kind of use case.

Has this already been discussed elsewhere?

Not that I could find

Links to previous discussion of this feature:

No response

從 argparse.ArgumentParser、解析器的 _actions 集合、subparser choices 和 get_default() 開始。確定用於取得 action parser 的 public method 的預期範圍和行為，包括它應如何支援所描述的預設值驗證使用情境。完成的標準是 API 及其行為已獲得明確定義，且該 feature 已由適當的測試涵蓋。