用于组合其他选项的 Argparse 快捷选项 [英] Argparse shortcut option for combining other options

问题描述

假设我有一个输入文件选项和一个输出文件选项.我怎样才能创建一个结合这两者的选项?例如:

Let's say I have an input file option and an output file option. How can I create an option that combines the two? For example:

$ ./my_script.py -i input.txt -o output.txt

可以组合为:

$ ./my_script.py --io input_output.txt

你可能会说我可以用 -io 来组合这两个选项，但是 -io filename 是 -i -o filename 的快捷方式>，不是 -i 文件名 -o 文件名.

You might say that I could do -io to combine both options, but -io filename is a shortcut for -i -o filename, not -i filename -o filename.

我认为可以将 dest=('input', 'output') 添加到我的 .add_argument() 调用中，但这引发了错误dest 必须是一个字符串.

I thought that it might be possible to add dest=('input', 'output') to my .add_argument() call, but that raised an error that dest must be a string.

我尝试在一侧添加一个带有 --io 的互斥组，在另一侧添加一组 -i 和 -o一边，但是当程序使用 --help 运行时，-i 和 -o 的帮助文本不再显示:

I tried adding a mutually exclusive group with --io on one side and a group of -i and -o on the other side, but the help texts for -i and -o did not show up any more when the program was run with --help:

usage: myscript.py [-h] [--io] [-i INPUT] [-o OUTPUT]

optional arguments:
  -h, --help  show this help message and exit
  --io        Use file as both input and output

此外，互斥的部分似乎不起作用.我仍然可以使用 --io 和单独的 -i 和 -o 选项调用脚本，并且不会引发错误.

Also, the mutually exclusive part didn't seem to work. I am still allowed to call the script with --io and the individual -i and -o options, and no error is raised.

这是我的骨架代码:

import argparse

parser = argparse.ArgumentParser()

parser.add_argument("-i", "--input", help="Input file")
parser.add_argument("-o", "--output", help="Output file")

parser.parse_args()

带组的代码:

import argparse

parser = argparse.ArgumentParser()

exclusive = parser.add_mutually_exclusive_group()
exclusive.add_argument("--io", help="Input and Output")

sub = exclusive.add_argument_group()
sub.add_argument("-i", "--input", help="Input file")
sub.add_argument("-o", "--output", help="Output file")

args = parser.parse_args()

if args.io:
    in_file = out_file = args.io
else:
    in_file = args.input
    out_file = args.output

推荐答案

解释为什么事情不起作用比提出解决方案更容易.

It is easier to explain why things don't work than to suggest a solution.

是的，dest 必须是字符串；没有提供 dest 值的列表或元组.但是您的 in_file = out_file = args.io 很好地解决了这个问题.您也可以使用:

Yes, dest must be a string; there's no provision for a list or tuple of dest values. But your in_file = out_file = args.io addresses that issue just fine. You could have also used:

 args.in_file=args.out_file = args.io

在解析后按摩 args 值没有任何问题.

There's nothing wrong with massaging the args values after parsing.

argument_group 不是为嵌套而设计的，也不是向 mutually_exclusive_group 添加任何"(或与")逻辑的方式.也许在遥远的未来会有一种定义完整逻辑组合的方法，但现在不行.其实做测试并不难；很难定义 API 和使用格式.

argument_group is not designed for nesting, nor is it a way of adding 'any' (or 'and') logic to the mutually_exclusive_group. Maybe in the distant future there will be a way of defining a full set of logical combinations, but not now. Actually it isn't hard to do the tests; it's hard to define the API and the usage formatting.

还请记住，mutually_exclusive_group 用于格式化参数的使用和测试 co_ocurrance，而 argument_group 用于对参数帮助行进行分组.两个截然不同的目的.

Also keep in mind that mutually_exclusive_group is used to format the usage and test for co_ocurrance of arguments, while argument_group is used to group argument help lines. Two very different purposes.

如果 -i 是 store_true 参数，则 -io filename 将被理解为 -i -o filename.但是也翻译一下 -i filename -o filename 不在当前代码中(并且可能不常见到需要补丁).

If -i was a store_true argument then -io filename would be understood as -i -o filename. But translating it too -i filename -o filename is not in the current code (and probably not common enough to warrant a patch).

如果你还想使用-i、-o和--io(我更喜欢-- 对于 2 个字符标志)我可以建议一些事情:

If you still want to use -i, -o and --io (I prefer -- for 2 character flags) I can suggest a couple of things:

• 编写一个自定义用法来演示您想要的内容.如果很难写出清晰的用法，那么你的设计可能太复杂了.

• write a custom usage that demonstrates what you want. If it is hard to write a clear usage, then your design is probably too complicated.

在解析后做你自己的exclusive groups测试.args.in_file is None 是测试是否使用标志的好方法.另一种可能性是定义默认值，这样您就不必关心用户使用哪种组合.

do your own exclusive groups testing after parsing. args.in_file is None is a good way of testing whether a flag has been used or not. Another possibility is to define defaults such that you don't care which combination the user uses.

这篇关于用于组合其他选项的 Argparse 快捷选项的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！