create and authenticate an anonymous user

def anonymous_or_real(request):
	# do we have an existing user?
	if request.user.is_authenticated():
		return request.user
	else:
		# if not, create an anonymous user and log them in
		username = IntToLetters(randint(0, maxint))
		u = User(username=username, first_name='Anonymous', last_name='User')
		u.set_unusable_password()
		u.save()
		
		u.username = u.id
		u.save()
		
		# comment out the next two lines if you aren't using profiles
		p = UserProfile(user=u, anonymous=True)
		p.save()
		authenticate(user=u)
		login(request, u)
		return u

######## Anonymous authentication backend middleware #########

from django.contrib.auth.models import User

from myapp.models import UserProfile

class AuthenticationBackendAnonymous:
	'''
		This is for automatically signing in the user after signup etc.
	'''
	def authenticate(self, user=None):
		# make sure they have a profile and that they are anonymous
		# if you're not using profiles you can just return user
		if not user.get_profile() or not user.get_profile().anonymous:
			user = None
		return user
	
	def get_user(self, user_id):
		try:
			return User.objects.get(pk=user_id)
		except User.DoesNotExist:
			return None