Cookbook

This section includes practical examples of how to use some of the utilities in this package.

Fixing super() Resolution for type() created classes

When trying to programatically create classes using the type() constructor, or the types.new_class() constructor, you may encounter the following problem when wanting to use a parameterless super() call later on:
TypeError: super(type, obj): obj must be an instance or subtype of type

Here is a simple example, to reproduce the above case with:

class Something:
    def truth(self):
        return 42


class MyThing:
    def __new__(cls, *args, **kwargs):
        dunder_dict = {
            **cls.__dict__,
            "__init__": lambda *a, **kw: None
        }
        dunder_dict.pop("__new__")

        kls = type(
            cls.__name__,
            (Something,),
            dunder_dict
        )

        return kls()

    def truth(self):
        return super().truth() + 8


if __name__ == '__main__':
    my_thing = MyThing()
    my_thing.truth()  # TypeErrror

Using utilities from this package, the above can be fixed via:

from drizm_commons.utils import (
    decorate_class_object_methods,
    decorators
)


class Something:
    def truth(self):
        return 42


class MyThing:
    def __new__(cls, *args, **kwargs):
        dunder_dict = {
            **cls.__dict__,
            "__init__": lambda *a, **kw: None
        }
        dunder_dict.pop("__new__")

        kls = type(
            cls.__name__,
            (Something,),
            dunder_dict
        )
        kls = decorate_class_object_methods(
            kls,
            decorators.resolve_super_auto_resolution,
        )

        return kls()

    def truth(self):
        return super().truth() + 8


if __name__ == '__main__':
    my_thing = MyThing()
    my_thing.truth()  # 50

See the reference for both of these Methods:

• resolve_super_auto_resolution

• decorate_class_object_methods