decoratemeta.py

import inspect

class Meta(type):
    def __init__(cls, name, bases, attrs):
        for attr, value in attrs.items():
            if inspect.isfunction(value):
                setattr(cls, attr, decorate(value))
        for base in bases:
            for attr in dir(base):
                value = getattr(base, attr)
                if inspect.ismethod(value):
                    setattr(cls, attr, decorate(value))

def decorate(func):
    # Check the flag to prevent double decoration.
    if getattr(func, '_decorated', False):
        return func
    def decorated(instance, *args, **kwargs):
        return func(instance, *args, **kwargs)
    # Set the flag to prevent double decoration.
    decorated._decorated = True 
    return decorated