Demo/pdist/cmdfw.py

   1 "Framework for command line interfaces like CVS.  See class CmdFrameWork."
   2
   3
   4 class CommandFrameWork:
   5
   6     """Framework class for command line interfaces like CVS.
   7
   8     The general command line structure is
   9
  10             command [flags] subcommand [subflags] [argument] ...
  11
  12     There's a class variable GlobalFlags which specifies the
  13     global flags options.  Subcommands are defined by defining
  14     methods named do_<subcommand>.  Flags for the subcommand are
  15     defined by defining class or instance variables named
  16     flags_<subcommand>.  If there's no command, method default()
  17     is called.  The __doc__ strings for the do_ methods are used
  18     for the usage message, printed after the general usage message
  19     which is the class variable UsageMessage.  The class variable
  20     PostUsageMessage is printed after all the do_ methods' __doc__
  21     strings.  The method's return value can be a suggested exit
  22     status.  [XXX Need to rewrite this to clarify it.]
  23
  24     Common usage is to derive a class, instantiate it, and then call its
  25     run() method; by default this takes its arguments from sys.argv[1:].
  26     """
  27
  28     UsageMessage = \
  29       "usage: (name)s [flags] subcommand [subflags] [argument] ..."
  30
  31     PostUsageMessage = None
  32
  33     GlobalFlags = ''
  34
  35     def __init__(self):
  36         """Constructor, present for completeness."""
  37         pass
  38
  39     def run(self, args = None):
  40         """Process flags, subcommand and options, then run it."""
  41         import getopt, sys
  42         if args is None: args = sys.argv[1:]
  43         try:
  44             opts, args = getopt.getopt(args, self.GlobalFlags)
  45         except getopt.error, msg:
  46             return self.usage(msg)
  47         self.options(opts)
  48         if not args:
  49             self.ready()
  50             return self.default()
  51         else:
  52             cmd = args[0]
  53             mname = 'do_' + cmd
  54             fname = 'flags_' + cmd
  55             try:
  56                 method = getattr(self, mname)
  57             except AttributeError:
  58                 return self.usage("command %r unknown" % (cmd,))
  59             try:
  60                 flags = getattr(self, fname)
  61             except AttributeError:
  62                 flags = ''
  63             try:
  64                 opts, args = getopt.getopt(args[1:], flags)
  65             except getopt.error, msg:
  66                 return self.usage(
  67                         "subcommand %s: " % cmd + str(msg))
  68             self.ready()
  69             return method(opts, args)
  70
  71     def options(self, opts):
  72         """Process the options retrieved by getopt.
  73         Override this if you have any options."""
  74         if opts:
  75             print "-"*40
  76             print "Options:"
  77             for o, a in opts:
  78                 print 'option', o, 'value', repr(a)
  79             print "-"*40
  80
  81     def ready(self):
  82         """Called just before calling the subcommand."""
  83         pass
  84
  85     def usage(self, msg = None):
  86         """Print usage message.  Return suitable exit code (2)."""
  87         if msg: print msg
  88         print self.UsageMessage % {'name': self.__class__.__name__}
  89         docstrings = {}
  90         c = self.__class__
  91         while 1:
  92             for name in dir(c):
  93                 if name[:3] == 'do_':
  94                     if docstrings.has_key(name):
  95                         continue
  96                     try:
  97                         doc = getattr(c, name).__doc__
  98                     except:
  99                         doc = None
 100                     if doc:
 101                         docstrings[name] = doc
 102             if not c.__bases__:
 103                 break
 104             c = c.__bases__[0]
 105         if docstrings:
 106             print "where subcommand can be:"
 107             names = docstrings.keys()
 108             names.sort()
 109             for name in names:
 110                 print docstrings[name]
 111         if self.PostUsageMessage:
 112             print self.PostUsageMessage
 113         return 2
 114
 115     def default(self):
 116         """Default method, called when no subcommand is given.
 117         You should always override this."""
 118         print "Nobody expects the Spanish Inquisition!"
 119
 120
 121 def test():
 122     """Test script -- called when this module is run as a script."""
 123     import sys
 124     class Hello(CommandFrameWork):
 125         def do_hello(self, opts, args):
 126             "hello -- print 'hello world', needs no arguments"
 127             print "Hello, world"
 128     x = Hello()
 129     tests = [
 130             [],
 131             ['hello'],
 132             ['spam'],
 133             ['-x'],
 134             ['hello', '-x'],
 135             None,
 136             ]
 137     for t in tests:
 138         print '-'*10, t, '-'*10
 139         sts = x.run(t)
 140         print "Exit status:", repr(sts)
 141
 142
 143 if __name__ == '__main__':
 144     test()