question for register_model()

[y b S]

Hi all,

 I am currently studying Django source code, then i have one question:

in registry.py, 

for app_config in self.app_configs.values():
               app_config.import_models()

import_models() uses self.apps.all_models

but when this variable is filled?

 and when  and how register_model() is called ?

it seems related to metaclass __new__ function , but i can not figure it out

thanks 

regards