object references

bruno at modulix onurb at xiludom.gro
Tue Mar 28 10:21:53 CEST 2006

DrConti wrote:
> Hi Bruno, hi folks!
> thank you very much for your advices.
> I didn't know about  the property function.
> I learned also quite a lot now about "references".
> Ok everything is a reference but you can't get a reference of a
> reference...
> I saw a lot of variations on how to solve this problem, but I find
> actually that the "property approach" is the most natural of all.

So I need to add a little correction to the code snippet (sorry, got
confused by your namings - ie 'ObjectClass' - and some recent
exploration I did about per-instance descriptors) : Actually, using a
property as an *instance* attribute won't work - unless the class
redefine __getattribute__ this way:

class ObjectClass(object):
  def __getattribute__(self, name):
    v = object.__getattribute__(self, name)
    if not isinstance(v, types.FunctionType) \
       and hasattr(v, '__get__'):
      return v.__get__(self, self.__class__)
    return v

> Basically the idea there is that you build up this list of class
> attributes

These are not *class* attributes, but *instance* attributes.

I think you should really take some time to learn more about Python's
object model, attribute lookup rules,  descriptors and metaclasses.

bruno desthuilliers
python -c "print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in 'onurb at xiludom.gro'.split('@')])"

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