/tests/regressiontests/cache/models.py

 1from django.db import models
 2from datetime import datetime
 3
 4def expensive_calculation():
 5    expensive_calculation.num_runs += 1
 6    return datetime.now()
 7
 8class Poll(models.Model):
 9    question = models.CharField(max_length=200)
10    answer = models.CharField(max_length=200)
11    pub_date = models.DateTimeField('date published', default=expensive_calculation)