Python class decorators are a powerful feature that allows developers to modify the behavior of a class or its methods. In this article, we will learn about Python decorators.
A class is a blueprint for an object, and it defines the properties and methods of an object. You can read more about Python class here.
Python decorators are a way of applying a function to a class or method, in order to add or change functionality. A class decorator is a function that takes a class as its argument and returns a new class. We can add additional functionality to the new class or use it to modify the behavior of the original class.
Python class decorators are a way to modify the behavior of a class or its methods. Apply them using the “@” symbol followed by the decorator function.. Let’s understand it using a simple example.
A simple example of a class decorator is one that adds a “greeting” feature to all of the methods in a class. Here is an example of such a decorator:
Let’s first write the decorator function as shown below.
# The decorator function def greeting(cls): # Goes through all of the class's methods for name, value in vars(cls).items(): # Check if the attribute is callable i.e a method if callable(value): # Add the greeting feature to the method setattr(cls, name, greet(value)) return cls
Next, implement the “greet” helper function.
# A helper function that adds the greeting feature def greet(func): def wrapper(*args, **kwargs): print("Hello, Welcome to class method") return func(*args, **kwargs) return wrapper
Finally, add the decorator to the class as shown below. we can see @greeting added above the class.
# Apply the decorator to the class @greeting class MyClass: def my_method(self): print("This is my method")
In this example, we define a decorator function
greeting decorator function takes a class as an argument. This decorator goes through all of the class’s methods and applies the greet function to each one. The greet function is a simple wrapper function that prints a greeting message before calling the original method.
When you create an object of MyClass and call the
my_method method, it will first print “Hello, Welcome to class method” and then “This is my method“.
# create MyClass object and call my_method myclass_obj = MyClass() myclass_obj.my_method()
Hello, Welcome to class method This is my method
In this way, we can use class decorators to add functionality to the class methods, without modifying the original method definition.
Some common uses of Python class decorators
These are some common uses of Python class decorators.
Use class decorators to log method calls and their arguments for debugging and monitoring the application.
2. Permission checks
Use class decorators to check the user’s permission before allowing the method’s call.
Class decorators can be used to cache the result of a method call so that it doesn’t have to be recalculated every time it is called.
Class decorators can be used to measure the time taken by a method to execute, which can be useful for performance optimization.
5. Singleton pattern
Finally, python class decorators can be used to implement the singleton pattern, which ensures that a class has only one instance throughout the lifetime of the application.
In conclusion, class decorators are a powerful feature in Python that allows developers to modify the behavior of a class or its methods