77 - formfield_function implementation seems to prevent subclasses of fields to provide own default form fields

[klipstein]

I have created a custom field, by subclassing db.models.CharField, which provides its own formfield-method, which points to a custom form field, using the method described here: http://docs.djangoproject.com/en/dev/howto/custom-model-fields/#specifying-the-form-field-for-a-model-field

But my method never receives an empty form_class argument, as the formfield_function evaluates by isinstance, rather than direct lookup on the class.

Original link: http://code.google.com/p/dojango/issues/detail?id=77