Understanding Python Classes and Objects

Python is fundamentally an object-oriented programming language, where virtually everything is treated as an object — each possessing properties and methods. A class in Python acts as a blueprint for constructing such objects, enabling developers to encapsulate data and functionality together in a clean, reusable format.

Creating a Class

To define a class in Python, the class keyword is used. Below is a basic example of defining a class named MyClass with a property x:

class MyClass:
    x = 5

Instantiating an Object

After defining the class, you can create an instance (object) from it. Here’s how you instantiate the class and access its property:

p1 = MyClass()
print(p1.x)

The __init__() Method

The __init__() method is a special function that automatically executes when a new object is instantiated. It is commonly used to initialize object attributes:

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

p1 = Person("John", 36)
print(p1.name)
print(p1.age)

The __str__() Method

The __str__() method returns a user-friendly string representation of the object. Without it, Python returns a less readable default string:

Without __str__():

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

p1 = Person("John", 36)
print(p1)

With __str__():

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

    def __str__(self):
        return f"{self.name}({self.age})"

p1 = Person("John", 36)
print(p1)

Defining Object Methods

Methods are functions that belong to an object. They are defined within the class using the def keyword. Here is an example of a method that prints a greeting:

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

    def myfunc(self):
        print("Hello my name is " + self.name)

p1 = Person("John", 36)
p1.myfunc()

The self Parameter

The self parameter refers to the current instance of the class and is used to access variables that belong to the class. Although conventionally named self, it can technically be any valid identifier:

class Person:
    def __init__(mysillyobject, name, age):
        mysillyobject.name = name
        mysillyobject.age = age

    def myfunc(abc):
        print("Hello my name is " + abc.name)

p1 = Person("John", 36)
p1.myfunc()

Modifying Object Properties

Object properties can be modified directly after the object is created:

p1.age = 40

Deleting Object Properties

Properties can be removed using the del keyword:

del p1.age

Deleting Objects

Entire objects can be deleted using the del statement:

del p1

The pass Statement

If a class body is intentionally left empty, use the pass statement to avoid syntax errors:

class Person:
    pass

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