#!/usr/bin/env python2.4

import code

class TypedDictionary(dict):
  def __setitem__(self, key, value):
    if self.has_key(key):
      t = type(self[key])
      if t != type(value):
        try:
          value = t(value)
        except Exception:
          raise TypeError, \
                "illegal assignment to '%s':" \
                " %s cannot be coerced to %s" \
                  % (key, type(value), t)
    dict.__setitem__(self, key, value)

code.interact(local=TypedDictionary())