14.3.3.5 Option attributes

Python 2.5

14.3.3.5 Option attributes

The following option attributes may be passed as keyword arguments to parser.add_option(). If you pass an option attribute that is not relevant to a particular option, or fail to pass a required option attribute, optparse raises OptionError.

  • action (default: "store")

    Determines optparse's behaviour when this option is seen on the command line; the available options are documented above.

  • type (default: "string")

    The argument type expected by this option (e.g., "string" or "int"); the available option types are documented below.

  • dest (default: derived from option strings)

    If the option's action implies writing or modifying a value somewhere, this tells optparse where to write it: dest names an attribute of the options object that optparse builds as it parses the command line.

  • default (deprecated)

    The value to use for this option's destination if the option is not seen on the command line. Deprecated; use parser.set_defaults() instead.

  • nargs (default: 1)

    How many arguments of type type should be consumed when this option is seen. If > 1, optparse will store a tuple of values to dest.

  • const

    For actions that store a constant value, the constant value to store.

  • choices

    For options of type "choice", the list of strings the user may choose from.

  • callback

    For options with action "callback", the callable to call when this option is seen. See section 14.3.4, Option Callbacks for detail on the arguments passed to callable.

  • callback_args, callback_kwargs

    Additional positional and keyword arguments to pass to callback after the four standard callback arguments.

  • help

    Help text to print for this option when listing all available options after the user supplies a help option (such as "-help"). If no help text is supplied, the option will be listed without help text. To hide this option, use the special value SUPPRESS_HELP.

  • metavar (default: derived from option strings)

    Stand-in for the option argument(s) to use when printing help text. See section 14.3.2, the tutorial for an example.

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