maze's thoughts

class LazyDict(dict):
    def __getattr__(self, attr):
        if attr in self:
            return self[attr]
        else:
            raise AttributeError, "'%s' object has no attribute '%s'" \
                % (self.__class__.__name__, attr)

    def __setattr__(self, attr, value):
        if hasattr(super(LazyDict, self), attr):
            raise AttributeError, "'%s' object already has attribute '%s'" \
                % (self.__class__.__name__, attr)
        self[attr] = value

>>> from lazydict import LazyDict
>>> foo = LazyDict()
>>> foo.bar = 42
>>> foo.bar
42
>>> foo.biz = LazyDict()
>>> foo.biz.qux
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "lazydict.py", line 6, in __getattr__
AttributeError: LazyDict instance has no attribute 'qux'
>>> foo.biz.qux = object()
>>> foo.biz.qux
<object object at 0xb7d26468>

>>> # Import the operator built-in module
>>> import operator
>>> from django.db.models import Q
>>> from mytest.models import Test
>>> # Create an arbitrary set of test-data
>>> for x in xrange(0, 99): Test(test=x).save()
>>> # The lookups
>>> lookups = [Q(test=1), Q(test=2), Q(test=23), Q(test=42)]
>>> # Here we use reduce()
>>> print Test.objects.filter(reduce(operator.or_, lookups))
[<Test test=1>, <Test test=2>, <Test test=23>, <Test test=42>]