I am looking into design patterns and best practices, especially on class composition (see my old question). I have a specific example where I found it really hard to implement a good OOP design for.
Simple(?) example:
Say there the concept of a garage which holds cars and there is a call to an external service whose response gives information about each car present in a garage.
This is an example response I want to capture and create classes for:
[{'carID': '1x148i-36y5-5rt2',
'carDimensions': {'top': 275,
'left': 279,
'width': 75,
'height': 75},
'carAttributes': {'weight': {'weightLevel': 'medium',
'value': 1.6},
'topSpeed': {'sppedLevel': 'good',
'value': 0.7},
'noise': {'noiseLevel': 'low',
'value': 0.32},
'accessories': [{'optionsLevel': 'poor',
'quality': 2.8}]}},
{'carID': '223a3-33e5-4ea3',
'carDimensions': {'top': 241,
'left': 234,
'width': 71,
'height': 65},
'carAttributes': {'weight': {'weightLevel': 'light',
'value': 1.1},
'topSpeed': {'sppedLevel': 'great',
'value': 1.6},
'noise': {'noiseLevel': 'high',
'value': 0.97},
'accessories': [{'optionsLevel': 'great',
'quality': 3.2}]}}]
Below are my class design approach.
I tried creating a Car
class that extracts each field like so:
class `Car`:
def __init__(self, car_response_dictionary):
self.car = car_response_dictionary
def get_carID(self):
return self.car.get("carID")
# etc.
and another class to handle some calculations based on the carDimensions
:
class Size:
def __init__(self, top, left, width, height):
self.top = top
self.left = left
self.width = width
self.height = height
def get_coordinates(self):
bottom = self.left + self.height
right = self.top + self.width
return (self.left, self.top), (bottom, right)
and a class to capture the concept of a garage which holds a list of Car
objects:
class Garage:
def __init__(self, datestamp, cars):
self.datestamp = datestamp
self.cars = cars
# do stuff based on cars
So, my idea is to create an instance of a Garage
and get the response list in cars
, I try to unpack each car as a Car
instance object by iterating through the cars
list of dictionaries and -using class composition- create a Car
instance for each car.
At this point I find impossible to implement my design in Python and I think that maybe the approach in my design is to be blamed or my poor understanding of class composition.
If someone could provide a simple code implementation for the above example that would be very educational for me. Even if that means that new design is proposed (e.g. I was contemplating of making a Response
class).