getopts 1.0.4

Yet another getopt library for Python

getopt-py

Yet another getopt library for Python.

Motivation

Python already has several argument parers. But the C-style getopt parser that comes with the standard Python library does not take advantage of the flexible syntax of a script language. And the argparse parser does not allow for the ordered processing of the arguments. This library was ported to Python from getopt-tcl to fill this gap.

Features

The feature set is based on GNU getopt_long:

• Short options. Options may be combined (-a -b -c is equivalent to -abc). Option arguments, if any, may appear with or without a space (-o value is equivalent to -ovalue).
• Long options. Option arguments, if any, may appear with or without an equal sign (--option value is equivalent to --option=value).
• Optional arguments are supported. The optional argument for a short option must be specified without a space (-ovalue) and for a long option must be specified with an equal sign (--option=value).
• Options (with or without arguments) and optionless arguments may appear in any order.
• -- can be used to denote the end of options.

Usage

getopts.getopts(argv, optstring)

All parameters are mandatory:

• argv - The argument list (e.g., sys.argv)
• optstring - A dictionary containing the valid options and a specification of whether they take an argument. The keys are the options. The value may be 0 if the option takes no argument, or 1 if it takes an argument. Instead of 0 or 1, it may specify a validation function that returns 1 if the argument is valid, or 0 otherwise. To specify the argument as optional, surround it in brackets (make it a list), with the optional second element specifying the default value.

The function returns an iterable object that, if evaluated, returns one of the following:

• -: An optionless argument. The value of the argument is stored in getopt.optarg.
• ?: An invalid option. An error message has been printed to getopt.stderr and the option that caused the error is stored in getopt.optopt.
• All other values: A valid option. This value is also stored in getopt.optopt. If the option takes an argument, the value is stored in getopt.optarg.

The following variable names are available:

• getopt.optind: The index of the next argv.
• getopt.optopt: The last option processed.
• getopt.optarg: The argument to the last option.

Example

getopt = getopts.getopts(sys.argv, {
    "h": 0         , "help"   : 0,
    "o": 1         , "output" : 1,
    "p": is_port   , "port"   : is_port,
    "v": [is_int,1], "verbose": [is_int,1]
})

for c in getopt:
    if c in ("-")             : opts.files.append(getopt.optarg)
    elif c in ("h", "help")   : usage() ; sys.exit(0)
    elif c in ("o", "output") : opts.output  = getopt.optarg
    elif c in ("p", "port")   : opts.port    = int(getopt.optarg)
    elif c in ("v", "verbose"): opts.verbose = int(getopt.optarg)
    else: sys.exit(1)

In the above example, single character options h, o, p, v may be specified with a single hyphen (-h, -o, -p, -v). Two hyphens are also accepted. The others must be specified with two hyphens (--help, --output, --port, --verbose).

• -h and --help take no arguments since the value that follows each is 0.
• -o and --output take any argument since the value that follows each is 1.
• -p and --port take an argument whose value must pass a test by is_port. For example,

def is_port(value):
    isport = False

    if(isinstance(value, int) and int(value) >= 1024 and int(value) < 65536):
        isport = True

    return isport

Finally, -v and --verbose take an optional argument whose value, if any, must pass the test by is_int. If no argument is specified, getopt.optarg defaults to 1.

See example-oo.py for a more complete example.

License

Apache 2.0