argparse:如果设置了标志，则忽略位置参数? [英] argparse: Ignore positional arguments if a flag is set?

问题描述

我想为命令提供3个参数:< version> ，<输入文件> 和<输出文件> 在正常使用情况下.除了有一个特定的标志-init ，该标志基本上将运行该程序，而无需任何输入和输出文件规范.

I want to provide the command with 3 arguments: <version>, <input file> and <output file> under normal usage. Except there's a specific flag --init, which will basically run the program without any input and output file specifications required.

因此，理想情况下，我将拥有一个用法如下的命令:

I would therefore ideally have a command which usage is:

py program.py --init

OR

py program.py< version><输入文件><输出文件>

但是，由于总是需要位置参数(因为在除-init 之外的任何其他情况下，所有三个参数都是必需的)，因此似乎无法干净地获得此语法，我想的方法是将3个位置参数设置为一个可选标志，如果在未调用-init 的情况下该可选标志不存在，则会引发异常.而且这一切看起来都很丑.

However, since positional arguments are always required (because all 3 are required in any other circumstance than --init), there seems to be no way to cleanly get this syntax and all I could think of would be to make the 3 positional arguments into an optional flag, raise an exception if the optional flag isn't there when --init is not called. And that all seems ugly.

到目前为止，我的代码:

My code so far:

def get_args():
    parser = argparse.ArgumentParser(description="Tool for FOO-ing a BAR.")
    parser.add_argument(dest="version", help="The version.")
    parser.add_argument(dest="input", help="The input file.")
    parser.add_argument(dest="output", help="The output file.")

    parser.add_argument("-i", "--init", dest="init", action="store_true", help="Foo Init.")

    return parser.parse_args()

要澄清:
必须指定所有3个参数(< version>< input>< output> ).
或
仅使用-init 标志运行该程序，并且应指定0个参数.

To Clarify:
Either all 3 arguments (<version> <input> <output>) MUST be specified.
OR
The program is only ran with --init flag and 0 arguments should be specified.

程序不应该接受带有0、1或2个指定参数的参数(没有-init 标志).

The program should NOT accept with 0, 1 or 2 arguments specified (without the --init flag).

推荐答案

parser.add_argument 具有默认参数(

parser.add_argument has a default parameter (docs) which can be used here for version, input and output parameters. Now you won't need third init param

这篇关于argparse:如果设置了标志，则忽略位置参数?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！