MetaClass.py

from abc import ABCMeta
from abc import abstractmethod


class LowerMeta(type):

    """Metaclass thats change the attr and method to be used
    with lowercase"""

    def __new__(lowerattr_Metaclass, future_ClassName,
                future_ClassParents, future_ClassAttr):

        lowercase_attr = {}
        for name, val in future_ClassAttr.items():
            if not name.startswith("__"):
                lowercase_attr[name.lower()] = val
            else:
                lowercase_attr[name] = val

        return type(future_ClassName, future_ClassParents,
                    lowercase_attr)

class Foo(metaclass=LowerMeta): # define metaclass in python3^

    C = 10

    def ABC(self):
        return 3


# foo = Foo()
# print(foo.abc()) # if you call the method with upper case will not work


class DocMeta(type):

    def __init__(self, name, bases, attrs):
        for key, value in attrs.items():
            # skip special/private methods.
            if key.startswith("__"): continue
            # skip any non-callable.
            if not hasattr(value, "__call__"): continue
            # check for a doc string.
            if not getattr(value, "__doc__"):
                raise TypeError("{} must to havea  docstring".format(key))
        type.__init__(self, name, bases, attrs)

class Door(metaclass=DocMeta):

    def __init__(self, number, status):
        self.number = number
        self.status = status

    def open(self):
        ''' now the method must have a docstring'''
        self.status = "open"

    def close(self):
        ''' now the method must have a docstring'''
        self.status = "closed"

# door = Door(1, 'open')
# print(door.status)


class Car(metaclass=ABCMeta):
    """Another metaclass that you can not instantiate
        just Inherit. or will raise a TypeError
        TypeError: Can't instantiate abstract class Car with
        abstract methods chage_gear, start_engine"""

    def __init__(self, carName, carModel, carColor):
        self.carName = carName
        self.carModel = carModel
        self.carColor = carColor

    @abstractmethod
    def chage_gear(self):
        pass

    @abstractmethod
    def start_engine(self):
        pass

car = Car('Uno', 'Volks', 'White')