[Tutor] What is a mixin class?

[Danny Yoo]

> Wow, Danny.  I am impressed.  I am not sure that this should not be 
> called a 'mash-up' rather than a 'mix-in' but it has really been food 
> for thought.

Thank you, but this isn't an original contribution.  I mostly adapted the 
stuff in papers like:

     http://www.cs.utah.edu/plt/publications/aplas06-fff.pdf


> What else have you got stashed away?  Have you got a book on the way?

Not yet.


> You should at least put this recipe into the Python Cookbook. There is 
> not much on mix-ins in there.

The example I gave isn't quite right because of the thread-safety issue. 
I should revisit that observer code later to handle thread safety before 
putting it into the Cookbook.


Best of wishes!