Python's OOP Wonderland: Classes and Objects Explored

Python Classes and Objects

Classes/Objects

Python is an object-oriented programming language. Nearly everything that happens in Python has an element with attributes and functions.

Objects and classes form the backbone of any Python program, without which programs would not be able to interpret user commands and function correctly. A deep knowledge of how Python classes and objects interact is vital for becoming a productive Python programmer.

Python is an object-oriented programming language, so everything is treated as an object, making it easier for developers to write reusable and more organized code instead of opting for traditional procedural approaches. A class acts like a blueprint or template for multiple objects with similar attributes to be created at once.

Python classes are user-defined data structures with attributes and methods created via calls to their methods. An instance can then be created by calling those methods, with each instance having its own set of attributes with unique values for those attributes that reflect an object's properties; additionally, each instance also comes equipped with its own methods that can help alter or modify this state of the object.

Python allows you to create classes by including the class keyword followed by its name in your scripts. The name will serve as an identifier within your code; additionally, class definitions can include docstrings that outline its purpose and usage; this practice helps improve code clarity and readability.

One class can be derived from another by listing its parent class name in parentheses after the class name. This allows you to share attributes and methods from both classes between themselves or define new class attributes and methods to enhance existing data types (for instance, if an abstract data type is expected in code, you could create an abstract class that emulates its methods so as to avoid duplicating code).

A class is more than its name: it also provides its own private and public methods, accessed using either class-level methods with self, which refer to instances of the class, or instance methods with an extra parameter called __self__ that work directly on individual objects to access or modify their state. Instance methods use individual instances as targets, while class methods operate across them all at the same time, allowing access to and manipulation of attribute values of objects within instances of that class.

As part of your class development process, when writing classes, it's possible to add methods that return or set the values of attributes at runtime. Each instance of a class may have unique values for attributes; the class-level method allows you to manipulate these values to alter overall behavior without impacting all instances; this feature saves both time and effort when changing states without having to alter all instances at once.

Creating A Class

A Class can be described as an object constructor or "blueprint" for creating objects.

In order to create classes make use of the term "class:

Example

Create a class called MyClass and the property x:

class MyClass:
  x = 5

Create Object

We can now use the class called MyClass in order to make objects.

Example

Create an object p1 and output the value of the x:

p1 = MyClass()
print(p1.x)

The __init__() Function

The above examples are objects and classes in their most basic form and they aren't really relevant in real-world applications.

To grasp the significance of classes, we must be aware of the built-in init() functions.

Every class has an init function, referred to as"__init__"() which is executed whenever the class is initiated.

Make use of the function __init__() function for assigning values to property objects and other functions required while the object is being constructed:

Example

Create a class titled Person using the function __init__() function for assigning values to names and ages:

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

p1 = Person("John", 36)

print(p1.name)
print(p1.age)

Notice: The __init__() function is activated automatically every when the program is created to create a new object.

The __str__() Function

The function __str__() function determines the information that is returned when a class object is represented by strings.

If the function __str__() operation is not defined the representation in string form of the object will be returned:

Example

The representation of a string object, minus the ______() functions:

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

p1 = Person("John", 36)

print(p1)

Example

The representation of a string object that uses the function __str__() method:

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)

Object Methods

Methods in objects can also be contained. Methods within objects refer to functions and are part of the object.

Let's design an algorithm within the Person class:

Example

Create a function that prints an invitation, then execute it on the p1 object:

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()

NOTE: The self parameter refers to the present instance and it is used to access variables belonging to the class.

The self Parameter

Self parameter is a reference to the current instance of class. self parameter refers for the instance currently in use and it is utilized to get access to variables belonging to this class.

It doesn't have to be identified as self You can name it whatever you want however, it must be the first parameter in any function that is part of the class:

Example

Make use of the terms MysillyObject or abc instead of self:

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()

Modify Object Properties

You can modify the properties of objects in this way:

Example

Set the age of p1 to 40:

p1.age = 40

Delete Object Properties

You can remove properties from objects making use of del keyword: "del" keyword:

Example

Eliminate the age property of the object p1:

del p1.age

Delete Objects

You can erase objects using "del" keyword:

Example

Remove the object p1:

del p1

The pass statement

classes definitions can't be empty, however in the event that you have an empty definition of a class definition without content you can add your pass declaration to prevent an error.

Example

class Person:
  pass