+ author=author,
+ author_name=author_name,
+ author_email=author_email,
+ description=description)
+
+ def revert(self, **kwargs):
+ """ commit this version of a doc as new head """
+ self.tree.commit(text=self.materialize(), **kwargs)
+
+
+def create_tag_model(model):
+ name = model.__name__ + 'Tag'
+ attrs = {
+ '__module__': model.__module__,
+ }
+ return type(name, (Tag,), attrs)
+
+
+def create_change_model(model):
+ name = model.__name__ + 'Change'
+
+ attrs = {
+ '__module__': model.__module__,
+ 'tree': models.ForeignKey(model, related_name='change_set'),
+ 'tags': models.ManyToManyField(model.tag_model, related_name='change_set'),
+ }
+ return type(name, (Change,), attrs)
+
+
+
+class DocumentMeta(ModelBase):
+ "Metaclass for Document models."
+ def __new__(cls, name, bases, attrs):
+ model = super(DocumentMeta, cls).__new__(cls, name, bases, attrs)
+ if not model._meta.abstract:
+ # create a real Tag object and `stage' fk
+ model.tag_model = create_tag_model(model)
+ models.ForeignKey(model.tag_model,
+ null=True, blank=True).contribute_to_class(model, 'stage')
+
+ # create real Change model and `head' fk
+ model.change_model = create_change_model(model)
+ models.ForeignKey(model.change_model,
+ null=True, blank=True, default=None,
+ help_text=_("This document's current head."),
+ editable=False).contribute_to_class(model, 'head')
+
+ return model
+