Python's Magic Methods: Leverage Their Power in Your Classes :

Python's Magic Methods: Leverage Their Power in Your Classes
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As a Python developer who wants to harness the power of object-oriented programming, you’ll love to learn how to customize your classes using special methods, also known as magic methods or dunder methods. A special method is a method whose name starts and ends with a double underscore. These methods have special meanings for Python.

Python automatically calls magic methods as a response to certain operations, such as instantiation, sequence indexing, attribute managing, and much more. Magic methods support core object-oriented features in Python, so learning about them is fundamental for you as a Python programmer.

In this tutorial, you’ll:

• Learn what Python’s special or magic methods are
• Understand the magic behind magic methods in Python
• Customize different behaviors of your custom classes with special methods

To get the most out of this tutorial, you should be familiar with general Python programming. More importantly, you should know the basics of object-oriented programming and classes in Python.

Get Your Code: Click here to download the free sample code that shows you how to use Python’s magic methods in your classes.

Getting to Know Python’s Magic or Special Methods

In Python, special methods are also called magic methods, or dunder methods. This latter terminology, dunder, refers to a particular naming convention that Python uses to name its special methods and attributes. The convention is to use double leading and trailing underscores in the name at hand, so it looks like .__method__().

Note: In this tutorial, you’ll find the terms special methods, dunder methods, and magic methods used interchangeably.

The double underscores flag these methods as core to some Python features. They help avoid name collisions with your own methods and attributes. Some popular and well-known magic methods include the following:

Special Method	Description
.__init__()	Provides an initializer in Python classes
.__str__() and .__repr__()	Provide string representations for objects
.__call__()	Makes the instances of a class callable
.__len__()	Supports the len() function

This is just a tiny sample of all the special methods that Python has. All these methods support specific features that are core to Python and its object-oriented infrastructure.

Note: For the complete list of magic methods, refer to the special method section on the data model page of Python’s official documentation.

The Python documentation organizes the methods into several distinct groups:

• Basic customization
• Customizing attribute access
• Customizing class creation
• Customizing instance and subclass checks
• Emulating generic types
• Emulating callable objects
• Emulating container types
• Emulating numeric types
• with statement context managers
• Customizing positional arguments in class pattern matching
• Emulating buffer types
• Special method lookup

Take a look at the documentation for more details on how the methods work and how to use them according to your specific needs.

Here’s how the Python documentation defines the term special methods:

A method that is called implicitly by Python to execute a certain operation on a type, such as addition. Such methods have names starting and ending with double underscores. (Source)

There’s an important detail to highlight in this definition. Python implicitly calls special methods to execute certain operations in your code. For example, when you run the addition 5 + 2 in a REPL session, Python internally runs the following code under the hood:

Python

>>> (5).__add__(2)
7

The .__add__() special method of integer numbers supports the addition that you typically run as 5 + 2.

Reading between the lines, you’ll realize that even though you can directly call special methods, they’re not intended for direct use. You shouldn’t call them directly in your code. Instead, you should rely on Python to call them automatically in response to a given operation.

Note: Even though special methods are also called magic methods, some people in the Python community may not like this latter terminology. The only magic around these methods is that Python calls them implicitly under the hood. So, the official documentation refers to them as special methods instead.

Magic methods exist for many purposes. All the available magic methods support built-in features and play specific roles in the language. For example, built-in types such as lists, strings, and dictionaries implement most of their core functionality using magic methods. In your custom classes, you can use magic methods to make callable objects, define how objects are compared, tweak how you create objects, and more.

Note that because magic methods have special meaning for Python itself, you should avoid naming custom methods using leading and trailing double underscores. Your custom method won’t trigger any Python action if its name doesn’t match any official special method names, but it’ll certainly confuse other programmers. New dunder names may also be introduced in future versions of Python.

Magic methods are core to Python’s data model and are a fundamental part of object-oriented programming in Python. In the following sections, you’ll learn about some of the most commonly used special methods. They’ll help you write better object-oriented code in your day-to-day programming adventure.

Controlling the Object Creation Process

When creating custom classes in Python, probably the first and most common method that you implement is .__init__(). This method works as an initializer because it allows you to provide initial values to any instance attributes that you define in your classes.

Read the full article at https://realpython.com/python-magic-methods/ »

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January 03, 2024 at 07:30PM
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