decorator

This guide will show you how to create a Python function decorator with a few easy steps, to help you separate different concerns in code. This guide does not aim to provide reference material regarding decorators, but rather explain the basics and provide a starting point for implementing your own decorator.

What is a decorator?

A Python decorator is similar to a Java annotation if you are familiar with the JVM language, where you decorate or “annotate” a function prefixing the decorator’s name with @. For example, the decorator below publishes the function hello() on the url / on a Flask application:

@app.route('/')
def hello() -> str:
    return 'Hello world from Flask!'

More broadly speaking, a decorator is a structural design pattern that lets you add behaviour to an object, by wrapping its decorated function in a new function that has the same signature.

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