I have made an abstract base class using metaclass=ABCMeta to implement some default methods and properties that all its derived classes should have, something like this:
class BaseClass(metaclass=ABCMeta):
def __init__(self):
self.params = OrderedDict()
# some function all children must implement
@abstractmethod
def fn():
pass
# some property all children will have
@property
def n_params(self):
return len(self.params)
Now, I want to count how many instances of each derived class are created, because I want to print their name with a number. I can easily implement it like this:
class ChildClass(BaseClass):
# nr of instances of ChildClass
_n = 0
def __init__(self, mu, sigma, amp):
# initialize ABC
super().__init__()
ChildClass._n += 1
self.name = f'ChildClass {ChildClass._n}'
# must be overridden by each child class
@staticmethod
def fn(name):
# do stuff
print(f'hello {name}')
However, I need to implement this in each class that derives from BaseClass separately. It would be much more elegant to implement it in BaseClass itself.
I am looking for something that works like the opposite of super(), maybe something like this:
class BaseClass(metaclass=ABCMeta):
# instance counter for derived classes
child()._n = 0
def __init__(self):
self.params = OrderedDict()
child()._n += 1
Can I implement a class level variable ChildClass._n in BaseClass? And if so, how can I access that variable in BaseClass.__init__?
Edit: To clarify: I already have a base class, from which I derive many other child classes. The fact that all these classes share many properties is one of the main reasons I decided to use a base class in the first place. It thus seems superfluous to need to implement something as simple as an instance counter separately in each derived class.
Accessing a child class variable seems to be already adressed here. The question that remains is, how do I define a class level variable in my abstract base class, that is different for each child class.
