class_loader.py

import inspect
import pkgutil
import importlib


def find_subsclasses(package, baseclass):
    for importer, modname, ispkg in pkgutil.iter_modules(package.__path__):
        if ispkg:
            continue
        module = importlib.import_module(package.__name__ + "." + modname, package.__name__)
        for name in dir(module):
            obj = getattr(module, name)
            if inspect.isclass(obj) and issubclass(obj, baseclass):
                yield obj