Is calling __new__ from a classmethod a pythonic way of doing?

Question

I want to build a class, that is handling and processing some data. So I want property to handle all the data processing silently when new data is passed And I want to overload init with classmethod, to have flexibility on parameters passed to instance creation. So I came up with the following solution :

class Cooper():
    def __init__(self):
        ...create all 'private' attributes 

    @classmethod
    def Dougie(cls,data,datatype):
         inst = cls.__new__(cls)
         setattr(inst,datatype,data)
         return inst

    @property
    def datatype1(self):
        return self._datatype1

    @datatype1.setter
    def datatype1(self,newdata):
        self._datatype1,self._datatype2,... = updatedata1(newdata)

    @property
    def datatype2(self):
        return self._datatype2

    @datatype2.setter
    def datatype2(self,newdata):
        self._datatype1,self._datatype2,... = updatedata2(newdata)

    ... to be continued...

Is this a pythonic way ? Or shoud I really create a metaclass (I get a little fir afraid there) ? What are the caveats ? Is there a better way ?