A simple approach to understanding classes and objects with python .
A new programmers’ dilemma in object oriented programming (OOP)
Delving deeper into programming requires learning new paradigms like object oriented programming, but for a new programmer who is just getting solid on conditionals, iterations and other forms of structured programming may find OOP a little bit difficult to understand. Well some may understand but breaking it down for a non-technical person may be tasking.
Well, when discussing OOP words like objects, classes, encapsulation, etc are often heard, but for this article I am going to stick to the concept of objects and classes.
OBJECTS
Objects in simple terms are a representation of real world elements like cars, dogs, chairs and the like. Objects share two main characteristics: data and behavior.
Lets use this analogy, take a Dog for example, it has a variety of data like breed, size, age, colour etcetera and behaviours like run, sleep, eat, bark.
In OOP, data are referred to as attributes or instances and behavior as methods. Methods are simply functions that call these objects in our code.
Objects(instances/attributes) Methods(behaviours)
Breed….eat()
Size ….. sleep()
Age…… bark()
Colour …..run()
CLASSES
A class is a blueprint from which individual objects are created. It can be seen as a model or a way to define attributes and behavior of an element. A class sort of houses all objects and methods
Example: class Dogs:
pass
maltese = Dogs()
print maltese
Here maltese is an object (instance) of the class Dogs.
Say we want to build a Dog management software.This would entail modeling real life entities.
i.e Dogs into software objects.
Lets go!
Dogs (attributes)
Breed
Size
Colour
Age
Methods (behaviours)
Eat()
Sleep()
Bark()
Run()
objects
Dog1
breed = alsetian
size = small
age = 2 years
colour = black
Dog2 :
breed = maltese
size = medium
age = 3 years
colour = white
Dog3
breed = chow chow
size = large
age = 5 years
colour = brown
So thus far, we have created objects from our data for three dogs. So lets code this in python. Yay!
Class Dogs:
def __init__(self, breed, size, age, colour)
self.breed =breed
self.size =size
self.age =age
self.colour =colour
def dogData_self(self):
print(“Dog details are: Dog breed- ” + breed + “Dog size: ” + size + “Dog age:” + age + “Dog colour: ” + colour)
Dog1 = Dogs(“alsetian”, ”small”, str(2)+”years”, ”black”)
Dog2 = Dogs(“maltese”, ”medium”, str(3)+”years”, ”white”)
Dog3 = Dogs(“chow chow ”,”large”, str(5)+”years”, ”brown ”)
Dog1.dogData_self()
The code outputs:
Dog details are: Dog breed — alsetian Dog size: small Dog age: 2years Dog colour: black
So here’s a breakdown of the code above:
So on the first line we created a class called Dogs.
On the second line we defined a method with a constructor init. Which helps create several instances or objects in this case were breed, size, age ,and colour. ”self” is a general convention used in python to initialize objects, so that when they are called the value assigned to them is returned.
On lines 3 to 6 we assigned the objects that would be used to call them.
On lines 7 to 9 we created a function that prints out the breed, size , age and colours of the dogs.
On lines 10 to 12 we give values to the objects i.e like creating a variable.
On lines 13 to 15 we called the methods (functions) this will return the values stored in them .
So there it is easy-peasy right! Well , more practice helps commit this to memory. So get out your keyboards and get your hands dirty with some code!
