Memcached Property Attributes ----------------------------- Setting the attribute will store the value in memcached; accessing the attribute will retrieve from memcached. Most useful as a way of simulating memcached "fields" on model instances. See the docstring for details.
Python's [descriptor][1] protocol can seem a bit esoteric at first; however, it can be invaluable in handling everyday idioms and patterns - something that the Django framework authors have taken advantage of in numerous occasions (e.g.: [auth middleware][2]). One such idiom I see and use often and would like to generalize is the attribute-existence check-or-set routine illustrated here: def get_foo(self): if not hasattr(self, '_foo'): self._foo = init_foo() return self._foo Rather than coding this up multiple times (either for a given class or across many unrelated classes), I would prefer to delegate this repetitive work to a descriptor and remain [DRY][3]. The means to this end is implemented as a variation on the Python `property` construct, and is intentionally over simplistic (I leave the details of the heavy lifting up to the reader). The basic premise shown in source here is simply straight-forward Python, a quick and dirty example of how it could be utilized within a Django context is shown here: from django.db import models from cacheprop import CacheProperty2 ARTIFACT_TYPES = ( ('F', _('File')), ('D', _('Directory')), ('A', _('Alias')), ) class Artifact(models.Model): # model fields name = models.CharField(maxlength=64) type = models.CharField(maxlength=1, choices=ARTIFACT_TYPES) file_metadata = CacheProperty2( lambda self: self.filemetadata_set.get(artifact__id=self.id) ) class FileMetadata(models.Model): byte_size = models.IntegerField() artifact = models.ForeignKey(Artifact, unique=True) [1]: http://users.rcn.com/python/download/Descriptor.htm [2]: http://code.djangoproject.com/browser/django/trunk/django/contrib/auth/middleware.py [3]: http://c2.com/cgi/wiki?DontRepeatYourself
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