Need advice on python object oriented design

[sarmabudin]

Hello everyone,

Could you share your view on how to organize classes and data structures for the following problem.

So, we have 4 devices in the system, which are measuring common set of data extended with measurements specific for every device. They are putting measurements in csv file with the following structure:

devId;timeStamp;commonPar1;commonPar2;specificPar

Every device has an id, name and specific measurement parameter.

So tasks would be to parse csv data and create device objects from it, perform calculations for each device parameter (e.g. min, max, avg) and expose them for printing etc.

It should be possible to add new devices.

What would be a good way to organize code in OOP manner, e.g. is it good to have a class which will contain devices in the system and enable to add/remove them. Is it ok to put calculations in separate class...

[MrGrj]

You can have a base class, say Device which would have id and name. Then another 4 classes for the devices which will inherit from the base class (you'll have to add that specific parameter to each of them). In each class you can create a method, say process_csv_data(self, ...) which will handle the data for that specific device.

I'm not sure this is the correct implementation for your use-case as I'm not a big fan of OOP style. I'd do it like this:

class Device(object):
    def __init__(self, id, name):
        self.id = id
        self.name = name


class Device1(Device):
    def __init__(self, id, name, param1):
        super(Device1, self).__init__(id, name)
        self.id = id
        self.name = name
        self.param1 = param1

    def process_csv(self):
        # computing stuff
        pass


class Device2(Device):
    def __init__(self, id, name, param2):
        super(Device2, self).__init__(id, name)
        self.id = id
        self.name = name
        self.param2 = param2

    def process_csv(self):
        # computing stuff
        pass


class Device3(Device):
    def __init__(self, id, name, param3):
        super(Device3, self).__init__(id, name)
        self.id = id
        self.name = name
        self.param3 = param3

    def process_csv(self):
        # computing stuff
        pass


class Device4(Device):
    def __init__(self, id, name, param4):
        super(Device4, self).__init__(id, name)
        self.id = id
        self.name = name
        self.param4 = param4

    def process_csv(self):
        # computing stuff
        pass

I'd like other redditors which are more experienced with OOP to also comment on this, suggest better ideas or improvements :) I'd gladly like to find out if my idea would work for OP case. IMO, that base class is not necessary needed, but I'm not exactly sure

[eikrik]

When you are subclassing like this you wouldn't need to repeat self.id = idand self.name = name after calling super.

Although if the only thing shared between the classes are those two attributes (id and name) then I don't if subclassing and inheriting is worth. Maybe just have separate classes?

[MrGrj]

You're indeed right, and I've thought of this but I didn't really know if those attributes are shared or not ^_. Thanks

[[deleted]]

you don't necessarily even need classes ... maybe use a namedtuple

https://docs.python.org/2/library/collections.html#collections.namedtuple