__init__() method
The __init__ method is similar to constructors in C++ and Java. Constructors are used to initializing the object’s state. Like methods, a constructor also contains a collection of statements(i.e. instructions) that are executed at the time of Object creation. It runs as soon as an object of a class is instantiated. The method is useful to do any initialization you want to do with your object.
# Sample class with init method
class Person:
# init method or constructor
def __init__(self, name):
self.name = name
# Sample Method
def say_hi(self):
print('Hello, my name is', self.name)
p = Person('Nikhil')
p.say_hi()
Output:
Hello, my name is Nikhil
Explanation:
In this example, we are creating a Person class and we have created a name instance variable in the constructor. We have created a method named as say_hi() which returns the string “Hello, my name is {name}”.We have created a person class object and we pass the name Nikhil to the instance variable. Finally, we are calling the say_hi() of the class.
Python Classes and Objects
A class is a user-defined blueprint or prototype from which objects are created. Classes provide a means of bundling data and functionality together. Creating a new class creates a new type of object, allowing new instances of that type to be made. Each class instance can have attributes attached to it for maintaining its state. Class instances can also have methods (defined by their class) for modifying their state.
To understand the need for creating a class and object in Python let’s consider an example, let’s say you wanted to track the number of dogs that may have different attributes like breed and age. If a list is used, the first element could be the dog’s breed while the second element could represent its age. Let’s suppose there are 100 different dogs, then how would you know which element is supposed to be which? What if you wanted to add other properties to these dogs? This lacks organization and it’s the exact need for classes.
Syntax: Class Definition
class ClassName:
# Statement
Syntax: Object Definition
obj = ClassName()
print(obj.atrr)
The class creates a user-defined data structure, which holds its own data members and member functions, which can be accessed and used by creating an instance of that class. A class is like a blueprint for an object.
Some points on Python class:
- Classes are created by keyword class.
- Attributes are the variables that belong to a class.
- Attributes are always public and can be accessed using the dot (.) operator. Eg.: My class.Myattribute