Python CLI interface

cli.py

#!/usr/bin/env python3

import os, sys, argparse, traceback

class cli(object):
    """"""
    def __init__(self, prog, version, args=None):
        self.prog = prog
        self.version = version

        self.parser = argparse.ArgumentParser(prog=prog)
        self.parser.add_argument('-V', '--version', action='version', version=version)
        self.parser.add_argument('-v', '--verbose', action="store_true", help='set verbosity level. default: %(default)s')
        self.parser.add_argument('-vv', '--showtb', action="store_true", help='show traceback. default: %(default)s')
        self.parser.add_argument('-d', '--debug', type=int, default=0, help='set debug\n [0]none [1]local\n [2]remote. default: %(default)s')

        self.args = args
        self.cmds = None

    def __enter__(self):
        return self

    def __exit__(self, t, v, tb):
        try:
            args = self.parser.parse_args(self.args)
            if not hasattr(args, 'exe'):
                self.parser.print_usage()
            else:
                if hasattr(args, 'debug'):
                    if args.debug == 2:
                        try: import pydevd; pydevd.settrace(host='127.0.0.1')
                        except: return 0
                    elif args.debug == 1:
                        try: import pdb; pdb.set_trace()
                        except: return 0

                args.exe(args)
        except KeyboardInterrupt:
            return 0
        except Exception:
            e_t, e_v, e_tb = sys.exc_info()
            e_lines = traceback.format_exception(e_t, e_v, e_tb)

            e_caption = "%s:" % self.prog
            e_shift = len(e_caption) * " "
            print(e_caption, file=sys.stderr)

            if getattr(args, 'showtb', False):
                print(e_shift + '\n'.join(e_lines), file=sys.stderr)
            else:
                e_desc = e_lines[-2].split('\n')
                e_flist = e_desc[0].split(', ')

                print(e_shift + e_lines[-1].strip(), file=sys.stderr)
                print(e_shift + "In: %s %s\n%s%s" %
                      (e_flist[0], e_flist[1], e_shift, e_desc[1].strip()),
                      file=sys.stderr
                )

            print(e_shift + "for help use --help\n", file=sys.stderr)
            return 2

    def deffunc(self, f):
        self.parser.set_defaults(exe=f)

    def arg(self, *a, **kw):
        self.parser.add_argument(*a, **kw)

    def cmd(self, name, **kw):
        if self.cmds is None:
            self.cmds = self.parser.add_subparsers(help='commands')

        p = self.cmds.add_parser(name, **kw)
        p.set_defaults(cmd=name)
        p.arg = lambda *a, **kw: p.add_argument(*a, **kw) and p
        p.exe = lambda f: p.set_defaults(exe=f) and p
        return p

########## Usage example:
"""
cli.py --help
usage: example [-h] [-V] [-v] [-vv] [-d DEBUG] {start,stop} ...

positional arguments:
  {start,stop}          commands
    start               Start example
    stop                Stop example

optional arguments:
  -h, --help            show this help message and exit
  -V, --version         show program's version number and exit
  -v, --verbose         set verbosity level. default: False
  -vv, --showtb         show traceback. default: False
  -d DEBUG, --debug DEBUG
                        set debug [0]none [1]local [2]remote. default: 0
cli.py start -h
usage: example start [-h] [-c CONF] [-a HOST] [-p PORT]

optional arguments:
  -h, --help            show this help message and exit
  -c CONF, --conf CONF  session config file
  -a HOST, --host HOST  Example host. [8080]
  -p PORT, --port PORT  Example port. [0.0.0.0]
"""

name = "example"
version = "1.0.1"

def start(**kw): pass

def stop(**kw): pass

if __name__ == "__main__":
    with cli(name, version) as command:
        command.cmd('start', help='Start example')\
            .arg('-c', '--conf', type=str, help='session config file')\
            .arg('-a', '--host', type=int, default=8080, help='Example host. [%(default)s]')\
            .arg('-p', '--port', type=str, default="0.0.0.0", help='Example port. [%(default)s]')\
            .exe(lambda a: start(conf=a.conf, host=a.host, port=a.port, debug=a.debug, verbose=a.verbose))

        command.cmd('stop', help='Stop example')\
            .exe(lambda a: stop(debug=a.debug, verbose=a.verbose))