22 Feb Python Classes and Objects
Python is an interpreted high-level, structural, and object-oriented programming language. Since it is object-oriented, the concept of classes and objects is well-discussed and implemented. A class is the basis of object-oriented programming in Python. In this tutorial, we will learn about Classes and Objects in Python. A class is a template for an object, whereas an object is an instance of a class.
What is a class in Python?
As discussed above, a class is a blueprint for objects in Python. We can easily create a class like this:
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class name_of_class: # Statement1 # Statement2 # Statement3 . . . StatementN |
Class Definition in Python
The class keyword is used to create a class in Python. The class is a reserved word in Python. In the below example, we will see how to create a class in Python:
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# creating a class with a property val # the class keyword is used to create a class class Studyopedia: val = 100 print(Studyopedia) |
Output
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<class '__main__.Studyopedia'> |
What is an object in Python?
An object is an instance of a class i.e. object is created from a class. An object represents real-life entities, for example, a Bike is an object. The object has State, Behavior, and Identity:
- Identity: Name of Bike
- State (Attributes): The data of the object Bike i.e. Color, Model, Weight, etc.
- Behavior (Methods): Behavior of object Bike like to Drive, Brake
Let us now see the representation, with Bike as an object:
How to Create an Object in Python
Considering the above example of classes in Python, we can easily create an object.
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# creating a class with a property val # the class keyword is used to create a class class Studyopedia: val = 100 print(Studyopedia) # object ob ob = Studyopedia() # displaying the value using the object ob print("Value = ",ob.val) |
Output
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<class '__main__.Studyopedia'> Value = 100 |
Now, we can easily create a sample Python program on Classes and Objects. Let’s see.
Example – Python Classes and Objects
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# class class Bike: # attributes of Bike name = "Hayabusa" body = "GEN III" engine = 1340 # Custom Python function def demoFunc(self): print("\nBike = ", self.name) print("Body = ", self.body) print("Engine (cc) = ", self.engine) # Objects b1 = Bike() b2 = Bike() # Accessing using the 1st object print("Bike name = ",b1.name) print("Bike Engine = ",b1.engine) # calling using the 2nd object b2.demoFunc() |
Output
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Bike name = Hayabusa Bike Engine = 1340 Bike = Hayabusa Body = GEN III Engine (cc) = 1340 |
Python _init_() Function
The classes in Python have __init__() function. Like constructors in Java, the __init__() function executes when the object gets created. Using this method, easily assign values to object properties.
Let us understand with an example, wherein we will create a class Students and values will be assigned using the __init__(). We have also created object functions:
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class Students: # using the __init__ function def __init__(self, sname, ssub, sgrade): self.sname = sname self.ssub = ssub self.sgrade = sgrade # custom function def demofunc(self): print("I am " + self.sname) print("I am interested in the Subject " + self.ssub) # creating 3 objects for class Students st1 = Students("Amit", "Programming", "A+") st2 = Students("Rohit", "Science", "A") st3 = Students("Shreyas", "Math", "B+") # calling the custom function using objects st1.demofunc() st2.demofunc() st3.demofunc() |
Output
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I am Amit I am interested in the Subject Programming I am Rohit I am interested in the Subject Science I am Shreyas I am interested in the Subject Math |
Above, we have also used the self parameter. The class methods in Python have the first parameter as self to access the class variable. A method with no argument should also have an argument self However, we can give it any name. It is not mandatory to use the word self.
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