Question

I’m trying to achieve the following:

class Data(object):
    def __init__(self, data):
        self.data = data
        self.valid = False
        #Analyze and validate data
        self.preprocess_data()
        self.validate_data()

    def preprocess_data():
        pass

    def validate_data():
        #process data

class MyData(Data):
    def __init__():
        super(MyData,self).__init__(data)

    def preprocess_data(self):
        #preprocess it

When a subclass executes the overriden preprocess_data method, I want to automatically perform the following operation: self.data = self.data.copy()

How can this be done (if at all)? I thought about decorating preprocess but I don’t think that overridden methods that are decorated in the base class inherit the “decoration”

Answer 1

class Data(object):
    def __init__(self, data):
        self.data = data
        self.valid = False
        #Analyze and validate data
        self._preprocess_data()
        self.validate_data()
    def _preprocess_data(self):
        if self.preprocess_data.im_func != Data.preprocess_data.im_func:
            self.data = self.data.copy()
        return self.preprocess_data()

This tests if the function behind self.preprocess_data is Data.preprocess_data; if not it copies your data. Of course this requires you to call _preprocess_data in your class so the additional code is actually executed.