OptParse and Constant values

Robert Kern robert.kern at gmail.com
Thu Aug 12 18:41:40 CEST 2010


On 8/12/10 11:19 AM, J wrote:
> How do you use OptParse with constants?
>
> Example:
> usage = 'Usage: %prog [OPTIONS]'
>      parser = OptionParser(usage)
>      parser.add_option('-l','--level',
>                        action='store_const',
>                        default=LOG_INFO,
>                        help='Set the log level to inject into syslog (either an\
>                        integer [0 - 7] or one of LOG_EMERG, LOG_ALERT,LOG_CRIT,\
>                        LOG_ERR, LOG_WARNING, LOG_NOTICE, LOG_INFO, LOG_DEBUG')
>      (options,args) = parser.parse_args()
>
>      print options
>
> always returns {'level':None} regarless of whether I call it with an
> int (0 - 7) or the const name (LOG_*)

http://docs.python.org/library/optparse#standard-option-actions

'store_const' means that the option is a flag without arguments and stores the 
value provided by the 'const' keyword to add_option() (it defaults to None so 
that's what you get when you use that flag). This is not what you want. You just 
want the default 'store' action.

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco




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