get the number of attributes with values that an object has

attrs_with_values.py

class Computer(object):
    name = None
    serial = None
    model = None
    kind = None
    attrs_with_value = None

    def __init__(self, *args, **kwargs):
        self.name = kwargs.get('name', None)
        self.serial = kwargs.get('serial', None)
        self.model = kwargs.get('model', None)
        self.kind = kwargs.get('kind', None)
        self.attrs_with_value = 0

    @classmethod
    def print_computers(cls, computers_):
        for computer in computers_:
            print('{} : {}'.format(
                computer.name if computer.name else computer.kind,
                computer.attrs_with_value
            ))


macBookPro = Computer(name='MacBook Pro',
                   serial='FFX',
                   kind='Laptop')


iMac = Computer(kind='iMac 27.0',
                model='2017')

clon = Computer(serial='FFX', kind='Desktop')


computers = [macBookPro, iMac, clon]

Computer.print_computers(computers)

for obj in computers:
    print('\n')
    for key, value in obj.__dict__.items():
        if value is not None:
            if key != 'attrs_with_value':
                print(key, value)
                obj.attrs_with_value += 1

print('\n')
Computer.print_computers(computers)