Import latest options.py from bup-0.17.

This has new support for default values in square brackets, so let's use
that.

main.py

@@ -49,7 +49,7 @@ sshuttle [-l [ip:]port] [-r [username@]sshserver[:port]] <subnets...>
 sshuttle --firewall <port> <subnets...>
 sshuttle --server
 --
-l,listen=  transproxy to this ip address and port number [default=0]
+l,listen=  transproxy to this ip address and port number [0.0.0.0:0]
 H,auto-hosts scan for remote hostnames and update local /etc/hosts
 N,auto-nets  automatically determine subnets to route
 r,remote=  ssh hostname (and optional username) of remote sshuttle server
@@ -57,9 +57,9 @@ x,exclude= exclude this subnet (can be used more than once)
 v,verbose  increase debug message verbosity
 seed-hosts= with -H, use these hostnames for initial scan (comma-separated)
 noserver   don't use a separate server process (mostly for debugging)
-server     [internal use only]
-firewall   [internal use only]
-hostwatch  [internal use only]
+server     (internal use only)
+firewall   (internal use only)
+hostwatch  (internal use only)
 """
 o = options.Options('sshuttle', optspec)
 (opt, flags, extra) = o.parse(sys.argv[1:])

options.py

-import sys, textwrap, getopt, re
+"""Command-line options parser.
+With the help of an options spec string, easily parse command-line options.
+"""
+import sys
+import textwrap
+import getopt
+import re
 
 class OptDict:
     def __init__(self):
@@ -14,15 +20,44 @@ class OptDict:
         return self[k]
 
 
+def _default_onabort(msg):
+    sys.exit(97)
+
+
+def _intify(v):
+    try:
+        vv = int(v or '')
+        if str(vv) == v:
+            return vv
+    except ValueError:
+        pass
+    return v
+
+
 class Options:
-    def __init__(self, exe, optspec, optfunc=getopt.gnu_getopt):
+    """Option parser.
+    When constructed, two strings are mandatory. The first one is the command
+    name showed before error messages. The second one is a string called an
+    optspec that specifies the synopsis and option flags and their description.
+    For more information about optspecs, consult the bup-options(1) man page.
+
+    Two optional arguments specify an alternative parsing function and an
+    alternative behaviour on abort (after having output the usage string).
+
+    By default, the parser function is getopt.gnu_getopt, and the abort
+    behaviour is to exit the program.
+    """
+    def __init__(self, exe, optspec, optfunc=getopt.gnu_getopt,
+                 onabort=_default_onabort):
         self.exe = exe
         self.optspec = optspec
+        self._onabort = onabort
         self.optfunc = optfunc
         self._aliases = {}
         self._shortopts = 'h?'
         self._longopts = ['help']
         self._hasparms = {}
+        self._defaults = {}
         self._usagestr = self._gen_usage()
 
     def _gen_usage(self):
@@ -48,17 +83,23 @@ class Options:
                     has_parm = 1
                 else:
                     has_parm = 0
+                g = re.search(r'\[([^\]]*)\]', extra)
+                if g:
+                    defval = g.group(1)
+                else:
+                    defval = None
                 flagl = flags.split(',')
                 flagl_nice = []
                 for f in flagl:
-                    f_nice = re.sub(r'\W', '_', f)
                     self._aliases[f] = flagl[0]
-                    self._aliases[f_nice] = flagl[0]
                     self._hasparms[f] = has_parm
+                    self._defaults[f] = _intify(defval)
                     if len(f) == 1:
                         self._shortopts += f + (has_parm and ':' or '')
                         flagl_nice.append('-' + f)
                     else:
+                        f_nice = re.sub(r'\W', '_', f)
+                        self._aliases[f_nice] = flagl[0]
                         assert(not f.startswith('no-')) # supported implicitly
                         self._longopts.append(f + (has_parm and '=' or ''))
                         self._longopts.append('no-' + f)
@@ -75,44 +116,52 @@ class Options:
                 out.append('\n')
         return ''.join(out).rstrip() + '\n'
 
-    def usage(self):
+    def usage(self, msg=""):
+        """Print usage string to stderr and abort."""
         sys.stderr.write(self._usagestr)
-        sys.exit(97)
+        e = self._onabort and self._onabort(msg) or None
+        if e:
+            raise e
 
     def fatal(self, s):
-        sys.stderr.write('error: %s\n' % s)
-        return self.usage()
+        """Print an error message to stderr and abort with usage string."""
+        msg = 'error: %s\n' % s
+        sys.stderr.write(msg)
+        return self.usage(msg)
 
     def parse(self, args):
+        """Parse a list of arguments and return (options, flags, extra).
+
+        In the returned tuple, "options" is an OptDict with known options,
+        "flags" is a list of option flags that were used on the command-line,
+        and "extra" is a list of positional arguments.
+        """
         try:
             (flags,extra) = self.optfunc(args, self._shortopts, self._longopts)
         except getopt.GetoptError, e:
             self.fatal(e)
 
         opt = OptDict()
-        for f in self._aliases.values():
-            opt[f] = None
+
+        for k,v in self._defaults.iteritems():
+            k = self._aliases[k]
+            opt[k] = v
+
         for (k,v) in flags:
-            while k.startswith('-'):
-                k = k[1:]
-            if k in ['h', '?', 'help']:
+            k = k.lstrip('-')
+            if k in ('h', '?', 'help'):
                 self.usage()
             if k.startswith('no-'):
                 k = self._aliases[k[3:]]
-                opt[k] = None
+                v = 0
             else:
                 k = self._aliases[k]
                 if not self._hasparms[k]:
                     assert(v == '')
-                    opt[k] = (opt._opts.get(k) or 0) + 1
+                    v = (opt._opts.get(k) or 0) + 1
                 else:
-                    try:
-                        vv = int(v)
-                        if str(vv) == v:
-                            v = vv
-                    except ValueError:
-                        pass
+                    v = _intify(v)
             opt[k] = v
-        for (f1,f2) in self._aliases.items():
-            opt[f1] = opt[f2]
+        for (f1,f2) in self._aliases.iteritems():
+            opt[f1] = opt._opts.get(f2)
         return (opt,flags,extra)