Wrapper objects

[Nick Coghlan]

redhog at takeit.se wrote:
> The wrapper objects needs to work as dictionary keys, to support
> printing, concatenation/addition, getitem/setitem and such things...

In that case, identifying exactly which operations you want to support, and 
using a metaclass based approach like mine or Bengt's should work.

However, I highly recommend the 'opt-in' approach to delegating magic methods. 
As Bengt discovered, there are a number of them that can break your class badly 
if you inadvertently delegate them (e.g. if you delegate __new__ or __init__, 
your class cannot be instantiated).

The Python Language Reference can tell you which methods need to be delegated to 
support a given operation: http://docs.python.org/ref/specialnames.html

The delegation may still not be completely transparent, since the delegated 
methods may not know how to deal with your wrapper objects. So you may require 
calls to methods like int() or str() in your application code to make the types 
work out correctly.

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at email.com   |   Brisbane, Australia
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