python之argparse模块

骑猪看日落 2022-06-07 07:07 254阅读 0赞

**一、简介**

argparse是python用于解析命令行参数和选项的标准模块，用于代替已经过时的optparse。

**二、使用步骤**

（1）import argparse\#导入argparse模块

（2）parser = argparse.ArgumentParser（）\#创建一个解析对象

（3）parser.add\_argument（）\#往该对象中添加你要关注的命令行参数和选项，一个add\_argument方法对应一个参数或选项

（4）parser.parse\_args（）\#调用parse\_args（）方法进行解析

**1）ArgumentParser**（prog=None，usage=None，description=None，epilog=None，parents=\[\]，formatter\_class=argparse.HelpFormatter，prefix\_chars=‘-’， fromfile\_prefix\_chars=None，argument\_default=None，conflict\_handler=‘error’，add\_help=True）

这个参数都是默认值，当调用parser.print\_help（）或者运行程序由于参数不正确（此时python解释器其实也是调用了print\_help（）方法）时，会打印这些描述信息，一般只需要传递description参数。

**2）add\_argument**（name or flags...\[,action\]\[,nargs\]\[,const\]\[,default\]\[,type\]\[,choices\]\[,required\]\[,help\]\[,metavar\]\[,dest\]）

其中，name or flags：命令行参数或选项，如果命令行参数没有给定，且没有设置default，则出错；如果是选项的话，则设置为None

nargs：命令行参数个数，一般使用通配符表示，如‘？’表示只用一个，‘\*’表示0~多个，‘+’表示至少一个

default：默认值

type：参数类型，默认为是字符串string类型，还有float、int等类型

help：和ArgumentParser方法中的参数作用相似，出现的常规也一致

以下为一参考实例：

import argparse
     
    def parse_args():
        description = usage: %prog [options] poetry-file
     
    This is the Slow Poetry Server, blocking edition.
    Run it like this:
     
      python slowpoetry.py <path-to-poetry-file>
     
    If you are in the base directory of the twisted-intro package,
    you could run it like this:
     
      python blocking-server/slowpoetry.py poetry/ecstasy.txt
     
    to serve up John Donne's Ecstasy, which I know you want to do.
     
     
        parser = argparse.ArgumentParser(description = description)
         
        help = The addresses to connect.
        parser.add_argument('addresses',nargs = '*',help = help)
     
        help = The filename to operate on.Default is poetry/ecstasy.txt
        parser.add_argument('filename',help=help)
     
        help = The port to listen on. Default to a random available port.
        parser.add_argument('-p',--port', type=int, help=help)
     
        help = The interface to listen on. Default is localhost.
        parser.add_argument('--iface', help=help, default='localhost')
     
        help = The number of seconds between sending bytes.
        parser.add_argument('--delay', type=float, help=help, default=.7)
     
        help = The number of bytes to send at a time.
        parser.add_argument('--bytes', type=int, help=help, default=10)
     
        args = parser.parse_args();
        return args
     
    if __name__ == '__main__':
        args = parse_args()
         
        for address in args.addresses:
            print 'The address is : %s .' % address
         
        print 'The filename is : %s .' % args.filename
        print 'The port is : %d.' % args.port
        print 'The interface is : %s.' % args.iface
        print 'The number of seconds between sending bytes : %f'% args.delay
        print 'The number of bytes to send at a time : %d.' % args.bytes</path-to-poetry-file>

如运行以下语句：

python test.py --port 1000 --delay 1.2 127.0.0.1 172.16.55.67

输出为：

The Address i: 127.0.0.1

The address is : 172.16.55.67 .  
The filename is : poetry/ecstasy.txt .  
The port is : 10000.  
The interface is : localhost.  
The number of seconds between sending bytes : 1.200000  
The number of bytes to send at a time : 10.