CONSTRUCT - Adding Functionality to the Overall System

[George Sakkis]

Ilias Lazaridis wrote:

> I like to add a method "writeDebug(self, msg)" to all (or the most
> possible) classes in the system.
>
> How do I do this?
>
> * with new style classes
> * with old style classes

Short answer: you can't do it for builtin or extension types:
>>> list.writeDebug = lambda msg: "You'd wish"
...
TypeError: can't set attributes of built-in/extension type 'list'

Longer asnwer: Make it a function instead of a method. This function
could try to call the respective method, and as a fallback it would
have hardcoded what to do for each supported class, something like:

def writeDebug(obj, msg):
    try: return obj.writeDebug(msg)
    except AttributeError:
        if isinstance(obj,list):
            # list msg
        elif isinstance(obj,tuple):
            # tuple msg
        ...
        else:
            # default object msg

If you insist though that you'd rather not use functions but only
methods, tough luck; you're better off with Ruby.

George