PEP proposal optparse

James Mills prologic at shortcircuit.net.au
Thu Sep 18 12:48:54 CEST 2008


Hi James,

I can't say I really agree with your
proposal. I tend to keep the help
descriptions of my options short
and concise and to the point.

Also, one must use the language's
features (indentation) to your advantage,
as doing so ensure readability.

For example (from my bhimport tool):

<snippet>
def parse_options():
   """parse_options() -> opts, args

   Parse any command-line options given returning both
   the parsed options and arguments.
   """

   parser = optparse.OptionParser(usage=USAGE, version=VERSION)

   parser.add_option("", "--date-format",
         action="store",type="str", default="%d/%m/%Y",
         dest="dateFormat",
         help="date format string")
   parser.add_option("", "--time-format",
         action="store", type="str", default="%H:%M:%S",
         dest="timeFormat",
         help="time format string")
   parser.add_option("", "--datetime-format",
         action="store", type="str", default="%H:%M:%S %d/%m/%Y",
         dest="datetimeFormat",
         help="datetime format string")

   opts, args = parser.parse_args()

   if len(args) < 2:
      parser.print_help()
      raise SystemExit, 1

   return opts, args
</snippet>

As you can see (as long as you're
reading this in fixed-width fonts)
it _is_ very readable.

cheers
James

On 9/18/08, James <jlnicolson at gmail.com> wrote:
> Hi,
>
>  I would like to know your thoughts on a proposed change to optparse
>  that I have planned. It is possible to add default values to multiple
>  options using the set_defaults. However, when adding descriptions to
>  options the developer has to specify it in each add_option() call.
>  This results in unreadable code such as:
>
>     parser.add_option('-q', '--quiet'    , action="store_false",
>  dest='verbose',
>         help = 'Output less information')
>     parser.add_option('-o', '--output'   , type='string',
>  dest='castordir'       , metavar='<DIR>'       ,
>         help = 'specify the wanted CASTOR directory where to store the
>  results tarball')
>     parser.add_option('-r', '--prevrel'  , type='string',
>  dest='previousrel'     , metavar='<DIR>'       ,
>         help = 'Top level dir of previous release for regression
>  analysis'             )
>
>  The same code could become much more readable if there was an
>  equivalent method of set_defaults for the description/help of the
>  option. The same code could then become:
>
>     parser.set_description(
>         verbose          = 'Output less information',
>         castordir        = 'specify the wanted CASTOR directory where
>  to store the results tarball',
>         previousrel      = 'Top level dir of previous release for
>  regression analysis')
>
>     parser.add_option('-q', '--quiet'    , action="store_false",
>  dest='verbose')
>     parser.add_option('-o', '--output'   , type='string',
>  dest='castordir'       , metavar='<DIR>'       )
>     parser.add_option('-r', '--prevrel'  , type='string',
>  dest='previousrel'     , metavar='<DIR>'       )
>
>  Help descriptions can often be quite long and separating them in this
>  fashion would, IMHO, be desirable.
>
>  Kind Regards,
>  James Nicolson
>
>
>  --
>  http://mail.python.org/mailman/listinfo/python-list
>


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-- "Problems are solved by method"



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