Currently, many developers discuss the output of attributes of argparse should be sorted or not?

>>> from argparse import ArgumentParser
>>> parser = ArgumentParser()
>>> _ = parser.add_argument('outstream')
>>> _ = parser.add_argument('instream')
>>> args = parser.parse_args(['out.txt', 'in.txt'])

# Keep the original order
>>> vars(args)

{'outstream': 'out.txt', 'instream': 'in.txt'}
# Order is sorted
>>> args
Namespace(instream='in.txt', outstream='out.txt')

IMHO, the attributes order should be keep the original order by default. If user would like use order the attributes order, we should add a param in `_AttributeHolder` to open sorting or not.

such as:
```
class _AttributeHolder(object):
    def __init__(self, sort=false):
        self.sort = sort

    def _get_kwargs(self):
        if sort:
            return sorted(self.__dict__.items())
        else:
            return self.__dict__.items()
```

some other bpos have discussed this topic too: issue39075、issue39058

What is the use-case for this? Why would anyone care in which order arguments are represented in the object repr?

Users or developers interact with program by cli(argparse), so attributes' output order affect users' interaction.

You'd need to elaborate on that. I've been using argparse for years and never once had presentational aspects affected by work. So, again, what is the actual use case for this?

1)>You'd need to elaborate on that. I've been using argparse for years and never once had presentational aspects affected by work. So, again, what is the actual use case for this?
  _AttributeHolder_ has sorted the args in `_get_kwargs()` and the offspring class override this function. So you have accepted this default behavior(do not use sorted attributes).
2)some guys have discussed this question in stackoverflow, such as: https://stackoverflow.com/questions/12268602/sort-argparse-help-alphabetically
3)This bpo stay in discussion stage and receive everyone's opinion ;)

The answer to the SO question seems rather complete to me and the only thing to be done on our side would be to document Formatter class and perhaps provide example implementation for sorting formatter. Assuming Raymond goes ahead with #39058 I'm still not sure who the proposed additional argument would be interesting to.

I don't think the SO question is relevant.  It's about changing the order of Actions in the Help and/or usage.    

Here it's a question of whether to sort the  `argparse.Namespace` display.  I think it's been adequately discussed in the recent bug/issues such as 39058.

paul said in issue 39058: `Anyways removing the sort makes sense, and the proposed change phrase "in the order attributes were added" is sufficiently general.`

I agree paul's opinion now. The functionality meets users' needs now, so we don't need spend much time in it;)

Am marking this as closed, out-of-date.

If needed, feel free to re-open.