Optimize ModelBase.__new__ app_label setup

[Ivan Dominic Baguio]

While browsing the ModelBase code, i noticed a possible improvement on the code logic.

under ModelBase.__new__, you will see:

        # Look for an application configuration to attach the model to.
        app_config = apps.get_containing_app_config(module)

        if getattr(meta, "app_label", None) is None:
            if app_config is None:
                # ...
            else:
                app_label = app_config.label

notice that app_config is defined above and outside the if getattr block.
the app_config variable is only used inside the if getattr block.

it would make sense to move the app_config initialization inside the if block, so it doesn't get unnecessarily called.

i've double checked the following:

• get_containing_app_config doesn't have any side effects, and is only a getter method
• app_config is only needed inside the if block

[Mariusz Felisiak]

Sounds reasonable. For the future, small cleanups don't need tickets.

​PR

[Mariusz Felisiak]

apps.get_containing_app_config() has a side-effect, it calls check_apps_ready() that raises an exception if all apps haven't been imported yet. IMO we shouldn't change this.

[Ivan Dominic Baguio]

I didn't notice that. I agree it shouldn't be modified.