Writing to stdout and a log file

[Michael Hoffman]

Mike wrote:

> I should've mentioned I want StdoutLog to subclass the 'file' type
> because I need all the file attributes available.

You might use a surrogate pattern. Here's one I use for this kind of 
situation, where I want to subclass but that can't be done for some reason.

class SurrogateNotInitedError(exceptions.AttributeError):
     pass

class Surrogate(object):
     def __init__(self, data):
         self._data = data

     def __getattr__(self, name):
         if name == "_data":
             raise SurrogateNotInitedError, name
         else:
             try:
                 return getattr(self._data, name)
             except SurrogateNotInitedError:
                 raise SurrogateNotInitedError, name

I'll leave it as an exercise to the reader to make this work when 
self._data is actually a list of objects instead of a single object. 
You'll obviously need special logic for different methods, like write(), 
since for some of them you will want to call every object in self._data, 
and others only a single object.
-- 
Michael Hoffman