What is a Decorator: Python For AI Explained Explained




A python snake wrapped around a symbolic ai brain

In the world of Python programming, a decorator is a powerful tool that allows programmers to modify the behavior of a function or class. It is a high-level Python feature that has a wide range of uses, from logging to enforcing access policies. In the context of Artificial Intelligence (AI), decorators can be used to streamline and organize code, making it easier to build complex AI models.

Decorators in Python are a significant feature, especially in the development of AI applications. They provide a simple syntax for calling higher-order functions. By definition, a decorator is a function that takes another function and extends the behavior of the latter function without explicitly modifying it. This concept is crucial in AI as it allows for the creation of more efficient and cleaner code.

Understanding Python Decorators

To fully grasp the concept of decorators in Python, it’s essential to understand that functions in Python are first-class objects. This means that functions in Python can be passed around and used as arguments, just like any other object (string, int, float, list, and so on). This feature paves the way for the creation of decorator functions.

At a fundamental level, a decorator is a callable Python object that is used to modify a function or a class. A reference to the function or class is passed to a decorator and the decorator returns a modified function or class. The modified functions or classes usually contain calls to the original function or class.

How Decorators Work

Decorators work as wrappers, modifying the behavior of the code before and after a target function execution, without the need to modify the function itself, augmenting the original functionality, thus decorating it. In Python, decorators dynamically alter the functionality of a function, method, or class without having to directly use subclasses or change the source code of the function being decorated.

Python’s decorators allow programmers to wrap another function in order to extend the behavior of the wrapped function, without permanently modifying it. In Decorators, functions are taken as the argument into another function and then called inside the wrapper function.

Decorator Syntax

The decorator syntax in Python is quite straightforward, although it might seem confusing if you’re not familiar with it. The symbol @ is used in conjunction with the name of the decorator function and placed above the function to be decorated. For example, @my_decorator is a way of saying that the function below is to be passed through the ‘my_decorator’ function.

This syntax is purely syntactic sugar, and a decorator could also be used by calling the decorator function and passing the function to be decorated as an argument. However, the @ syntax is much more readable and is therefore generally preferred.

Uses of Decorators in AI

Decorators have a wide range of uses in Python, especially in the field of AI. They can be used to log information, enforce access control and authentication, rate limit functions, cache results, track state, implement retry logic, and much more. All of these features can be extremely useful when building AI models, as they allow for more efficient and organized code.

For example, decorators can be used to log the input and output of a function, which can be very helpful for debugging purposes. They can also be used to enforce certain constraints on a function, such as ensuring that input is of a certain type or within a certain range. This can be particularly useful in AI, where the input to a function often needs to be carefully controlled.

Logging with Decorators

Logging is a common use case for decorators, and it’s particularly useful in AI programming. By using a decorator to log the inputs and outputs of a function, you can have a clear record of how your function is being used, which can be very helpful for debugging. This is especially true in AI, where algorithms can often be opaque and hard to understand.

Here’s an example of a simple logging decorator:

def log_decorator(func):
    def wrapper(*args, **kwargs):
        result = func(*args, **kwargs)
        print(f"{func.__name__}({args}, {kwargs}) = {result}")
        return result
    return wrapper

Enforcing Access Control with Decorators

Another common use of decorators is enforcing access control. This can be particularly useful in AI, where you might want to restrict access to certain functions based on user roles or other criteria. By using a decorator, you can centralize your access control logic in one place, making your code easier to understand and maintain.

Here’s an example of a decorator that enforces access control:

def admin_required(func):
    def wrapper(user, *args, **kwargs):
        if user.role != 'admin':
            raise Exception("This user is not an admin")
        return func(user, *args, **kwargs)
    return wrapper

Decorators in Python Libraries

Section Image

Many Python libraries make use of decorators. For example, the Flask web framework uses decorators to route URLs to functions. The pytest testing framework uses decorators to mark certain functions as tests or to specify test parameters. In the context of AI, libraries like TensorFlow and Keras also use decorators for various purposes.

For instance, TensorFlow uses decorators for defining static and dynamic graphs, while Keras uses decorators for defining custom layers and models. These decorators simplify the process of defining complex AI models, making it easier for developers to build and train their models.

Flask Decorators

Flask, a popular web framework in Python, uses decorators extensively. One of the most common uses of decorators in Flask is for routing, where decorators are used to bind a function to a URL route. This allows Flask to automatically call the correct function when a particular URL is accessed.

Here’s an example of a Flask route decorator:

def home():
    return "Hello, World!"

TensorFlow and Keras Decorators

TensorFlow and Keras, two popular libraries for building AI models in Python, also make use of decorators. TensorFlow uses decorators to define static and dynamic graphs, which are essential for building and training AI models. Keras uses decorators to define custom layers and models, allowing developers to extend the functionality of the library.

Here’s an example of a TensorFlow decorator:

def add(a, b):
    return a + b


In conclusion, decorators are a powerful feature in Python that allow programmers to modify the behavior of a function or class without changing its source code. They are particularly useful in the field of AI, where they can be used to streamline and organize code, making it easier to build complex models.

Whether you’re logging information, enforcing access control, or defining custom layers in an AI model, decorators can help you write cleaner, more efficient code. So the next time you’re working on a Python project, consider whether decorators might be a useful tool to include in your programming arsenal.

Share this content

Latest posts