Python abstract class shall force derived classes to initialize variable in __init__

I want to have an abstract class which forces every derived class to set certain attributes in its __init__ method.

I've looked at several questions which did not fully solve my problem, specifically here or here. This looked promising but I couldn't manage to get it working.

I assume my desired outcome could look like the following pseudo code:

from abc import ABCMeta, abstractmethod


class Quadrature(object, metaclass=ABCMeta):

    @someMagicKeyword            #<==== This is what I want, but can't get working
    xyz

    @someMagicKeyword            #<==== This is what I want, but can't get working
    weights


    @abstractmethod
    def __init__(self, order):
        pass


    def someStupidFunctionDefinedHere(self, n):
        return self.xyz+self.weights+n



class QuadratureWhichWorks(Quadrature):
    # This shall work because we initialize xyz and weights in __init__
    def __init__(self,order):
        self.xyz = 123
        self.weights = 456

class QuadratureWhichShallNotWork(Quadrature):
    # Does not initialize self.weights
    def __init__(self,order):
        self.xyz = 123 

Here are some of the things I have tried:

from abc import ABCMeta, abstractmethod


class Quadrature(object, metaclass=ABCMeta):

    @property
    @abstractmethod
    def xyz(self):
        pass


    @property
    @abstractmethod
    def weights(self):
        pass


    @abstractmethod
    def __init__(self, order):
        pass


    def someStupidFunctionDefinedHere(self, n):
        return self.xyz+self.weights+n



class QuadratureWhichWorks(Quadrature):
    # This shall work because we initialize xyz and weights in __init__
    def __init__(self,order):
        self.xyz = 123
        self.weights = 456

Then I try to create an instance:

>>> from example1 import * 
>>> Q = QuadratureWhichWorks(10)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: Can't instantiate abstract class QuadratureWhichWorks with abstract methods weights, xyz
>>> 

Which tells me to implement the methods, but I thought I said that these are properties?

My current work-around has the flaw, that the __init__ method can be overwritten in the derived classes but for now this at least ensures (to me) that I always know that the requested properties are set:

from abc import ABCMeta, abstractmethod


class Quadrature(object, metaclass=ABCMeta):

    @abstractmethod
    def computexyz(self,order):
        pass


    @abstractmethod
    def computeweights(self,order):
        pass


    def __init__(self, order):
        self.xyz = self.computexyz(order)
        self.weights = self.computeweights(order)

    def someStupidFunctionDefinedHere(self, n):
        return self.xyz+self.weights+n



class QuadratureWhichWorks(Quadrature):

    def computexyz(self,order):
        return order*123

    def computeweights(self,order):
        return order*456


class HereComesTheProblem(Quadrature):

    def __init__(self,order):
        self.xyz = 123
        # but nothing is done with weights

    def computexyz(self,order):
        return order*123

    def computeweights(self,order): # will not be used
        return order*456

But the problem is

>>> from example2 import * 
>>> Q = HereComesTheProblem(10)
>>> Q.xyz
123
>>> Q.weights
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'HereComesTheProblem' object has no attribute 'weights'

How is this implemented correctly?

from Python abstract class shall force derived classes to initialize variable in __init__