argparse python modul 行为的解释：大写占位符来自哪里？

发布于 2024-11-25 07:05:37 字数 1339 浏览 0 评论 0 原文

我正在尝试编写一个命令行界面（第一次），在阅读了 argparse、optparse 和 getopt 后，我选择了 argparse 因为这里有关于 SO 和网络其他地方的一些建议。采纳了一点van Rossum 先生的建议，我连接了我的第一个命令行界面是这样的：

def main(argv=None):
    if argv is None:
        argv = sys.argv
    desc = u'some description'
    parser = argparse.ArgumentParser(description=desc)

    parser.add_argument('-s', '--search', help='Search for someone.')
    parser.add_argument('-c', '--do_something_else', help='Do something else.')

    args = parser.parse_args()
    print args

if __name__ == '__main__':
    sys.exit(main())

执行 python myscript.py -h 结果是：

usage: dblp.py [-h] [-s SEARCH] [-c DO_SOMETHING_ELSE]

some description

optional arguments:
  -h, --help            show this help message and exit
  -s SEARCH, --search SEARCH
                        Search for someone.
  -c DO_SOMETHING_ELSE, --do_something_else DO_SOMETHING_ELSE
                        Do something else.

所以我的第一个问题是：为什么是 SEARCH 和DO_SOMETHING_ELSE 用大写字母书写？ 第二个问题是：我是否违反了任何标准？ 是否有更好的方法（或者是我可以学习的一个很好的现实世界示例）如何使用 python 构建干净且有用的命令行界面？以及应该避免的陷阱、写cmd接口的时候？

原文

I am trying to write a command line interface (for the first time) and after reading up about argparse, optparse and getopt I chose argparse because of several recommendations here on SO and elswhere in the net. Adapting a little of the advice of Mr. van Rossum I hooked up my first command line interface like this:

def main(argv=None):
    if argv is None:
        argv = sys.argv
    desc = u'some description'
    parser = argparse.ArgumentParser(description=desc)

    parser.add_argument('-s', '--search', help='Search for someone.')
    parser.add_argument('-c', '--do_something_else', help='Do something else.')

    args = parser.parse_args()
    print args

if __name__ == '__main__':
    sys.exit(main())

Doing python myscript.py -h results in:

usage: dblp.py [-h] [-s SEARCH] [-c DO_SOMETHING_ELSE]

some description

optional arguments:
  -h, --help            show this help message and exit
  -s SEARCH, --search SEARCH
                        Search for someone.
  -c DO_SOMETHING_ELSE, --do_something_else DO_SOMETHING_ELSE
                        Do something else.

So my first question is: Why are SEARCH and DO_SOMETHING_ELSE written in CAPITAL LETTERS? The second question would be: Do I break any standards? Is there a better way (ore a nice real world example I can learn from) how to build clean and useful command line interfaces with python? And are there pitfalls one should avoid, when writing cmd interfaces?