argparse

In my python script, I want to be able to use an optional input parameter only when another optional parameter has been specified. Example: $ python myScript.py --parameter1 value1 $ python myScript.py --parameter1 value1 --parameter2 value2 But NOT: $ python myScript.py --parameter2 value2 How do I do this with argparse? Thanks! Use a custom action: import argparse foo_default=None class BarAction(argparse.Action): def __call__(self,parser,namespace,values,option_string=None): didfoo=getattr(namespace,'foo',foo_default) if(didfoo == foo_default): parser.error( "foo before bar!") else: setattr

In the argparse package the metavar parameter modifies the displayed help message of a program. The following program is not intended to work, it is simply used to demonstrate the behavior of the metavar parameter. import argparse if __name__ == '__main__': parser = argparse.ArgumentParser(description = "Print a range.") parser.add_argument("-range1", nargs = 3, type = int, help = "Specify range with: start, stop, step.", metavar = ("start", "stop", "step")) parser.add_argument("-range2", nargs = 3, type = int, help = "Specify range with: start, stop, step.", metavar = "r2") The corresponding

With python's argparse, how do I make a subcommand a required argument? I want to do this because I want argparse to error out if a subcommand is not specified. I override the error method to print help instead. I have 3-deep nested subcommands, so it's not a matter of simply handling zero arguments at the top level. In the following example, if this is called like so, I get: $./simple.py $ What I want it to do instead is for argparse to complain that the required subcommand was not specified: import argparse class MyArgumentParser(argparse.ArgumentParser): def error(self, message): self.print

can argparse be used to validate filename extensions for a filename cmd line parameter? e.g. if i have a python script i run from the cmd line: $ script.py file.csv $ script.py file.tab $ script.py file.txt i would like argparse to accept the 1st two filename cmd line options but reject the 3rd i know you can do something like this: parser = argparse.ArgumentParser() parser.add_argument("fn", choices=["csv","tab"]) args = parser.parse_args() to specify two valid choices for a cmd line option what i'd like is this: parser.add_argument("fn", choices=["*.csv","*.tab"]) to specify two valid file

tldnr: given a function, is there a way to automatically create an ArgumentParser from its signature? I've got a bunch of functions that I'd like to expose to the command line. So basically, a module: def copy(foo, bar, baz): ... def move(from, to): ... def unlink(parrot, nomore=True): ... if __name__ == '__main__': argparse stuff which can be called from the command line like this: python commands.py move spam ham python commands.py unlink --parrot Polly Although this is pretty straightforward to implement, there's a lot of wiring involved: parser = argparse.ArgumentParser(...) subparsers =

转： http://vra.github.io/2017/12/02/argparse-usage/ argparse 是python自带的命令行参数解析包，可以用来方便地读取命令行参数，当你的代码需要频繁地修改参数的时候，使用这个工具可以将参数和代码分离开来，让你的代码更简洁，适用范围更广。 argparse使用比较简单，常用的功能可能较快地实现出来，下面我分几个步骤， 以Python3为例 ，逐渐递增地讲述argparse的用法。 1. 基本框架 下面是使用argparser从命令行获取用户名，然后打印’Hello ‘+ 用户名，假设python文件名为 print_name.py : # file-name:print_name.pyimport argparsedef get_parser(): parser = argparse.ArgumentParser(description="Demo of argparse") parser.add_argument('--name', default='Great') return parserif __name__ == '__main__': parser = get_parser() args = parser.parse_args() name = args.name print('Hello {}'.format