url:  />
import argparse
parse = argparse.ArgumentParser()
parse.add_argument("a", help="params means")
parse.add_argument("-C", "--gc", default="count")
parse.add_argument("--ga", help="params means ga",dest='simple_value',choices=['A', 'B', 'C', 0])
parse.add_argument("--gb", help="params means gb",action="store_const",const='value-to-store')
args = parse.parse_args()
print args.simple_value,args.gb,args.gc

### add_argument 說明
不帶'--'的引數
    呼叫指令碼時必須輸入值
    引數輸入的順序與程式中定義的順序一致
'-'的引數
    可不輸入    add_argument("-a")
    類似有'--'的shortname，但程式中的變數名為定義的引數名
'--'引數
    引數別名: 只能是1個字元，區分大小寫
        add_argument("-shortname","--name", help="params means")，但程式碼中不能使用shortname
    dest: 引數在程式中對應的變數名稱 add_argument("a",dest='code_name')
    default: 引數預設值
    help: 引數作用解釋  add_argument("a", help="params means")
    type : 預設string  add_argument("c", type=int)
    action:

    store：預設action模式，儲存值到指定變數。
    store_const：儲存值在引數的const部分指定，多用於實現非布林的命令列flag。
    store_true / store_false：布林開關。 store_true.預設為False，輸入則為true。 store_flase 相反
    append：儲存值到列表，該引數可以重複使用。
    append_const：儲存值到列表，儲存值在引數的const部分指定。
    count: 統計引數簡寫輸入的個數  add_argument("-c", "--gc", action="count")
    version 輸出版本資訊然後退出。

    const:配合action="store_const|append_const"使用，預設值
    choices:輸入值的範圍 add_argument("--gb", choices=['A', 'B', 'C', 0])
    required : 預設False, 若為 True, 表示必須輸入該引數


==================================================================================
    Keyword Arguments:
        - option_strings -- A list of command-line option strings which    should be associated with this action.
        - dest -- The name of the attribute to hold the created object(s)
        - nargs -- The number of command-line arguments that should be  consumed. By default, one argument will be consumed and a single  value will be produced.
                     Other values include:

                - N (an integer) consumes N arguments (and produces a list)
                - '?' consumes zero or one arguments
                - '*' consumes zero or more arguments (and produces a list)
                - '+' consumes one or more arguments (and produces a list)

                    Note that the difference between the default and nargs=1 is that with the default, a single value will be produced, while with  nargs=1, a list containing a single value will be produced.
        - const -- The value to be produced if the option is specified and the  option uses an action that takes no values.
        - default -- The value to be produced if the option is not specified.
        - type -- A callable that accepts a single string argument, and returns the converted value.  
                    The standard Python types str, int,  float, and complex are useful examples of such callables.  If None,  str is used.
        - choices -- A container of values that should be allowed.
                    If not None,  after a command-line argument has been converted to the appropriate type, an exception will be raised if it is not a member of this collection.
        - required -- True if the action must always be specified at the command line. This is only meaningful for optional command-line  arguments.
        - help -- The help string describing the argument.
        - metavar -- The name to be used for the option's argument with the  help string. If None, the 'dest' value will be used as the name.

• 建立子parse,每個子parse對應自己的輸入引數

  

使用幫助

# python args_subparse.py -h
usage: args_subparse.py [-h] {create,list,delete} ...

positional arguments:
  {create,list,delete}  commands
    list                Listcontents
    create              Create a directory
    delete              Remove a directory

optional arguments:
  -h, --help            show this help message and exit
  
# python args_subparse.py create -h
usage: args_subparse.py create [-h] [--read-only] dirname

positional arguments:
  dirname      New directoryto create

optional arguments:
  -h, --help   show this help message and exit
  --read-only  Setpermissions to prevent writing to the directory
  
# python args_subparse.py delete -h
usage: args_subparse.py delete [-h] [--recursive] dirname

positional arguments:
  dirname          The directory to remove

optional arguments:
  -h, --help       show this help message and exit
  --recursive, -r  Remove thecontents of the directory, too
 
# python args_subparse.py list -h
usage: args_subparse.py list [-h] dirname

positional arguments:
  dirname     Directory tolist

optional arguments:
  -h, --help  show this help message and exit

多個subparser 使用同樣定義的引數
# add_help=False,必須指定，否則報-h重複定義
parents_parser = argparse.ArgumentParser(add_help=False)
parents_parser.add_argument('--foo', dest="foo", action='store_true')
parents_parser.add_argument('--bar', dest="bar", action='store_false')
parents_parser.add_argument('--baz', dest="baz", action='store_false')

parser = argparse.ArgumentParser()
subparsers = parser.add_subparsers(help='commands')
m_parser = subparsers.add_parser("mysql", parents=[parents_parser], help="mysql method")
m_parser.set_defaults(func=sub_mysql)
o_parser = subparsers.add_parser("oracle", parents=[parents_parser], help="oracle method")
o_parser.set_defaults(func=sub_oracle)
args = parser.parse_args()


參考
http://blog.csdn.net/songuooo/article/details/8373086
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