Master Python Programming: Your Ultimate Guide to Learning from Scratch by Gonzalez Dominguez Tomas

Author:Gonzalez Dominguez, Tomas
Language: eng
Format: epub
Published: 2024-02-12T00:00:00+00:00

Classes and objects

Python is an object-oriented programming language, meaning it allows users to define structures known as classes, which can model the real world intuitively and flexibly. Classes act as templates for creating objects, which are instances of these classes. Each object can have attributes (also known as properties) to maintain its state and methods (functions) to modify that state or perform operations. This article explores the fundamental concepts of classes and objects in Python, providing a solid foundation for understanding object-oriented programming (OOP) in this language.

Definition of Classes

A class is defined in Python using the `class` keyword, followed by the class name and a colon. The body of the class contains method definitions (which are functions associated with the class).

class MiClase:

def __init__(self, attribute):

self.attribute = attribute

def my_method(self):

print(f"Attribute value is {self.attribute}")

The `__init__` method is a special constructor that is called automatically when a new object of that class is created. It is used to initialize the attributes of the object. The first parameter of each method, `self`, is a reference to the current object and is used to access the object's attributes and methods.

Object Creation

To create an object (or instance) of a class, simply call the class as if it were a function, passing the arguments that the `__init__` method expects.

my_object = MyClass("value")

my_object.my_method() # Output: The attribute value is value

Attributes and Methods

Attributes are variables that belong to an object or class, and methods are functions that operate on the object or class.

- Instance attributes: They are unique for each object, defined within the `__init__` method or in any other method with `self.attribute_name`.

- Class attributes: They are shared by all instances of a class. They are defined outside any method and are accessed using the class name.

class MiClase:

class_attribute = "shared"

def __init__(self, instance_attribute):

self.instance_attribute = instance_attribute

- Instance methods: They operate on an instance of the class and have access to the `self` object.

- Class methods: They operate on the class itself and not on particular instances. They are defined with the `@classmethod` decorator and accept `cls` as the first parameter.

- Static methods: They do not operate on the class or on instances of the class and do not have special parameters such as `self` or `cls`. They are defined with the `@staticmethod` decorator.

Inheritance

Inheritance allows a class to inherit attributes and methods from another class. The base class (or superclass) provides attributes and methods to the derived class (or subclass).

class Base:

def base_metodo(self):

print("Base class method")

class Derived(Base):

def derived_method(self):

print("Derived class method")

Polymorphism

Polymorphism is the ability to use common interfaces for different types. In Python, this means that different classes can have methods with the same name, but different implementations.

Conclusion

Classes and objects are fundamental to object-oriented programming in Python, allowing developers to create reusable, organized, and easy-to-maintain code. Understanding how to define classes, create objects, and use inheritance and polymorphism are crucial steps to harnessing the full power of Python and writing efficient and effective programs.

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