It's weird, but it works! python: moduleclass

betterdict.py

__bases__ = (dict, )

def __missing__(self, key):
    self[key] = key
    return key

main.py

from moduleclass import moduleclass

with moduleclass:
    import betterdict

d = betterdict()
print(d['key']) # prints 'key'

moduleclass.py

import types
import builtins

from importlib import __import__
from contextlib import contextmanager


def _moduleclass_import(name, *args, **kwargs):
    module = __import__(name, *args, **kwargs)
    metaclass = getattr(module, '__metaclass__', type)
    bases = getattr(module, '__bases__', ())
    moduleclass = metaclass(name, bases, {
        key: value 
        for key, value in module.__dict__.items()
        if key not in {
            '__name__', '__dict__', '__loader__', '__builtins__', '__build_class__', '__package__', '__spec__'
        } and not isinstance(value, types.ModuleType)
    })
    return moduleclass
    

@contextmanager
def _moduleclass():
    builtins.__import__ = _moduleclass_import
    yield
    builtins.__import__ = __import__

moduleclass = _moduleclass()