public delegate bool OptionArgFunc (string option_name, string val, void* data) throws OptionError
The type of function to be passed as callback for g_option_arg_callback options.
The name of the option being parsed. This will be either a single dash followed by a single letter (for a short name) or two dashes followed by a long option name.
The value to be parsed.
true if the option was successfully parsed, false if an error occurred, in which case throws should be set with @set