How to build Hierarchies of dict's? (Prototypes in Python?)

[Toby]

Charles D Hixson wrote:
> a class whose sub-classes automatically have unique class variables of
> a determined form such that I can do a hierarchical search through them

Something like this?  
(scroll down to see the results)


# --- begin ---

class AttrSearch(object):
  @classmethod
  def getclassattrset(cls, name):
    s = set()
    if name in cls.__dict__:
      s.add((cls.__name__, cls.__dict__[name]))
    for base in cls.__bases__:
      try:
        s.update(base.getclassattrset(name))
      except AttributeError:
        pass
    return s

  def getattrset(self, name):
    s = set()
    try:
      s.add((None, self.__dict__[name]))
    except KeyError:
      pass
    s.update(self.__class__.getclassattrset(name))
    return s

  def __getattribute__(self, name):
    if name.startswith('__'): #XXX not pretty
      return object.__getattribute__(self, name)
    found = AttrSearch.getattrset(self, name)
    print 'Looking for "%s" in a %s instance, found %d candidates:' \
          % (name, self.__class__.__name__, len(found))
    print '\n'.join([ '  %-4s %s' % x for x in found ])
    print '(now choose wisely what to return)'

class A(AttrSearch):
  a = 1

class B(A):
  a = 2

class C(A):
  a = 3

class D(B, C):
  a = 4


D().a

# --- end ---


Results:

Looking for "a" in a D instance, found 4 candidates:
  A    1
  B    2
  C    3
  D    4
(now choose wisely what to return)


Toby