Re: Adding code and methods to a class dynamically

Sarir Khamsi wrote: 
I have a class (Command) that derives from cmd.Cmd and I want to add
methods to it dynamically. I've added a do_alias() method and it would
be nice if I could turn an alias command into a real method of Command
(that way the user could get help and name completion). The code would
be generated dynamically from what gets passed to the do_alias()
method. I've tried looking in the Python cookbook and have tried:

def funcToMethod(func, clas, method_name=None):
   setattr(clas, method_name or func.__name__, func)

class Command(object, cmd.Cmd):
   # ...
   def do_f1(self, rest): print 'In Command.do_f1()'
   def do_alias(self, rest):
      rest.strip() # remove leading and trailing whitespace
      pat = re.compile(r'^(\w+)\s+(\w+)$')
      mo = pat.search(rest)
      if mo:
         newName = mo.group(1)
         existingName = mo.group(2)
         code = 'def do_' + newName + '(self, rest):\n'
         code += '   self.do_' + existingName + '(rest)\n'
         exec code
         funcToMethod(getattr(newModule, 'do_' + existingName),
                      self,
                      'do_' + 'existingName')
      else:
         print 'Invalid alias command'

but this does not seem to work.

If it's truly just an alias you want, then something like this should work better. Replace everything in the if mo: section with this:

if mo:
    newName = mo.group(1)
    existingName = mo.group(2)
    existingMethod = getattr(self, 'do_' + existingName)
    setattr(self, 'do_' + newName, existingMethod)


-Peter
.