multiple inheritance of a dynamic list of classes?

[Bruno Desthuilliers]

devicerandom at gmail.com a écrit :
> Hi,
> 
(snip)
> - is there a better way than using multiple inheritance to plug-in
> dynamically commands in a Cmd command line?

Yes : use composition + delegation. Python makes it easy:

#foo.py
class Commands(object):
      def do_this(self,args):
           ...
      def do_that(self,args):
           ...
#bar.py
class Commands(object):
   def do_what(self, args):
     ...


I've seen I can do it by explicitely import them and using multiple
inheritance:

class MyCli(cmd.Cmd):
     def __init__(self, *plugins):
         self.plugins = plugins
         self._cache = {}

     def __getattr__(self, name):
         try:
             return self._cache[name]
         except KeyError:
             for plugin in self.plugins:
                 attr = getattr(plugin, name, None)
                 if attr is not None:
                     self._cache[name] = attr
                     return attr


my_cli = MyCli(foo.Command(), bar.Command())