An in-depth analysis of decorators in Python: the charm of Python code that beauty products cannot resist

Preface

The previous blogs have shared knowledge about machine learning with you. In this article, I will lead you to explore decorators in Python. Decorators are a powerful feature of Python and are widely used in daily programming. So, what are decorators? How to use it? Let us take a look next.

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What is a decorator?

Decorators, as the name suggests, are things used for decoration. In Python, the role of decorators is to decorate existing functions or methods to add new functionality without changing the original function code.

In Python, a decorator is essentially a function that takes a function as an argument and returns a new wrapped function. Simply put, a decorator is a way to wrap a function and improve its performance or behavior.

How to use decorators?

# Python
def my_decorator(func):
    def wrapper():
        print("Something is happening before the function is called.")
        func()
        print("Something is happening after the function is called.")
    return wrapper

def say_hello():
    print("Hello!")

say_hello = my_decorator(say_hello)

say_hello()

In the above code, my_decoratorit is a decorator whose parameter is a function and returns a function. This returned function is usually a nested function, that is, a function that wraps the passed in function.

When we call say_hello = my_decorator(say_hello), the function say_hellois my_decoratordecorated, and the call say_hello()is equivalent to executing wrapper()the function, so it will first print "Something is happening before the function is called.", then execute say_hellothe original function, print "Hello!", and finally print "Something is happening after the function is called.".

Python @ syntax simplifies decorator usage

In Python, we can use @syntax to simplify the use of decorators. The specific code is as follows:

# Python
def my_decorator(func):
    def wrapper():
        print("Something is happening before the function is called.")
        func()
        print("Something is happening after the function is called.")
    return wrapper

@my_decorator
def say_hello():
    print("Hello!")

say_hello()

In the above code, @my_decoratorthe syntax is equivalent to execution say_hello = my_decorator(say_hello), so that when we define the function, we can directly decorate it with a decorator.

Conclusion

Decorator is a very powerful tool in Python. It can help us add new functions without modifying the original function code, making the code more readable and reusable. If you still have any questions about decorators, please leave a message in the comment area and let us discuss and learn together.

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