I am originally a Django developer and now I'm trying to play some basic and pure python OOP. I'm all good until I tried importing an abstract base class to be inherited on my child classes
The error is:
Traceback (most recent call last):
File "inheritance.py", line 1, in <module>
from . abstract_base_class import Vehicle
ValueError: Attempted relative import in non-package
My folder structure is:
├── OOP
│ ├── __init__.py
│ ├── abstract_base_class.py
│ ├── classes.py
│ ├── inheritance.py
│ └── inheritance.pyc
My abstract_base_class.py is:
from abc import ABCMeta, abstractmethod
class Vehicle(object):
"""
@brief An example of Abstract Base Class
@attrs base_sale_price:
wheels:
"""
__metaclass__ = ABCMeta
"""
- A metaclass is the class of a class. Like a class defines how an
instance of the class behaves, a metaclass defines how a class behaves.
A class is an instance of a metaclass.
- This declares that the class is abstract
-- This will not run as long as there is an abstractmethod decorator
-- Try running this and it will result to:
--- TypeError: Can't instantiate abstract class Vehicle with
abstract methods vehicle_types
- Try removing this and the class will work just fine
"""
base_sale_price = 0
wheels = 0
def __init__(self, miles, make, model, year, sold_on, *args, **kwargs):
"""
@brief Constructs the object.
@attrs wheels: An integer representing the number of wheels the vehicle has.
miles: The integral number of miles driven on the vehicle.
make: The make of the vehicle as a string.
model: The model of the vehicle as a string.
year: The integral year the vehicle was built.
sold_on: The date the vehicle was sold.
"""
self.miles = miles
self.make = make
self.model = model
self.year = year
self.sold_on = sold_on
def sale_price(self):
"""
@brief TODO
"""
if self.sold_on is not None:
return 0.0
return 5000.0 * self.wheels
def purchase_price(self):
"""
@brief TODO
"""
if self.sold_on is None:
return 0.0
return self.base_sale_price - (.10 * self.miles)
@abstractmethod
def vehicle_types(self):
"""
@brief
The decorator enforces the child classes to define this method
"""
pass
x = Vehicle(1, 2, 3, 4, 5)
print x.miles
print x.vehicle_types()
My inheritance.py is:
from . abstract_base_class import Vehicle
class Car(Vehicle):
"""
@brief An example class inheriting the Vehicle Base Class
@attrs base_sale_price:
wheels:
"""
base_sale_price = 8000
wheels = 4
def vehicle_type(self):
"""
@brief TODO
"""
return 'car'
class Truck(Vehicle):
"""
@brief An example class inheriting the Vehicle Base Class
"""
base_sale_price = 10000
wheels = 4
def vehicle_type(self):
"""
@brief TODO
"""
return 'truck'
class Motorcycle(Vehicle):
"""
@brief An example class inheriting the Vehicle Base Class
"""
base_sale_price = 2000
wheels = 2
def vehicle_type(self):
"""
@brief TODO
"""
return 'motorcycle'
x = Car()
print x.wheels
I wish to remove the error so I can continue practicing my OOP codes
