Decorators in Python Definition
Decorators in Python are really useful. They let people who write code change how a function or class works without changing the original code. A decorator works by wrapping around another function. This means it can do something before or after the main function is run. Decorators in Python are a way to handle things that need to be done over and over again in a clean and simple way. Decorators in Python make it easy to add things to a function or class without messing with the original code.
Decorators in Python Example
To understand decorators in python in a way you need to know that functions in Python are like any other object. This means you can do lots of things with them. You can pass functions to functions. You can also return functions from functions.. You can assign functions to variables. Functions in Python are really important because they can be used in different ways. Decorators in python are based on this idea that functions in Python’re objects that you can use like anything else.
A decorator in Python is used to add extra functionality to a function without changing its original code.
Simple Decorator Example
Output
Explanation
my_decorator()is the decorator function.wrapper()adds extra behavior before and after the original function.@my_decoratorapplies the decorator tosay_hello().- The original function runs without being modified directly.
Why this Decorators in Python example matters
This example shows how decorators help in:
- Logging
- Authentication
- Performance measurement
- Code reusability
Decorators are widely used in web frameworks, APIs, and real-world Python applications.
A decorator is basically a function that takes another function and does something with it. It then gives you a function that does what the old function did but with some extra things added. People often call this “meta programming” because it is, like one part of the program is trying to change another part while the program is being put together.
Decorators in Python Simple Example
People usually add a decorator to a function by using the @ symbol. This @ symbol is put above where the function is defined. The @ symbol is sometimes called “pie syntax” because it looks like a pie. When you want to add a decorator to a function you just put the @ symbol and the decorator above the function. This is how you use decorators with the @ symbol or “pie syntax” on a function.
Code Example:
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 this decorators in python example, the @my_decorator syntax is a shorthand for writing say_hello = my_decorator(say_hello).
Decorators in Python Interview Questions
When you are in an interview python interview questions often include decorators. One thing people like to ask about is how to make decorators work with functions that need some information to work properly. To make a decorator work with any function you can use *args and **kwargs, in the wrapper function.
Decorators in Python Interview Questions
Beginner Level
- What are decorators in Python and why are they used?
- How do decorators work internally in Python?
- What is the purpose of the
@symbol in decorators? - What is the difference between a function and a decorator in Python?
- Can decorators be applied to both functions and methods?
Intermediate Level
- How does a decorator modify a function without changing its source code?
- What is the role of nested functions in decorators?
- Why is
functools.wrapsimportant when writing decorators? - What is the difference between decorators and closures in Python?
- How can multiple decorators be applied to a single function?
Advanced Level
- How do decorators in Python with arguments work?
- What happens when a decorator returns another function?
- Can a decorator accept both positional and keyword arguments?
- How are class-based decorators different from function-based decorators?
- How do decorators impact function performance and readability?
Practical & Scenario-Based Questions
- How would you use decorators for logging function execution?
- How can decorators be used for authentication and authorization?
- How do decorators help in caching and memoization?
- Explain a real-world use case where decorators improve code maintainability.
- When should decorators be avoided in Python applications?
Coding-Oriented Interview Questions
- Write a simple decorator to measure function execution time.
- Create a decorator that checks user permissions before executing a function.
- Write a decorator that accepts arguments and modifies function behavior.
- How would you debug a decorator that is not returning expected output?
- Convert a function-based decorator into a class-based decorator.
This way the decorator can take any number of arguments like the kind you write in a list or the kind you give a name to. Then it can pass those arguments to the original python function, which is the function that the decorator is supposed to be helping.
This makes the decorator very versatile which is nice when you are working with python and you want to use decorators. The python function and the decorator can work together nicely because of *args and **kwargs.
Decorating Functions with Parameters
Python
def decorator_with_args(func):
def wrapper(*args, **kwargs):
print(“Arguments received:”, args)
return func(*args, **kwargs)
return wrapper
@decorator_with_args
def multiply(a, b):
return a * b
print(multiply(10, 20))
Another important concept is “Chaining Decorators.” You can apply multiple decorators to a single function. They are applied from the bottom up (the one closest to the function runs first).
PW Skills Course Suggestion
If you are looking to master Python and software development, PW Skills offers specialized tracks to take you from a beginner to a professional level. For those specifically interested in the logic behind decorators and advanced programming:
- Decode Python with DSA Course: This course covers the fundamentals of Python, moving into advanced concepts like decorators, and focuses heavily on Data Structures and Algorithms to prepare you for top-tier tech roles.
- Check out the detailed guide here: Python Decorators with Types and Examples
FAQs Related to Decorators in Python
What is the primary purpose of decorators in Python?
The main reason is that decorators let programmers change how a function or class works. Decorators, in Python help keep the code simple by letting you put code around different functions, which is really helpful because it means you do not have to write the same code over and over again and this is what people mean when they say decorators help keep the code DRY, which means Don’t Repeat Yourself and that is the whole point of using decorators in Python.
Can a decorator return a value?
Yes. So when we use a decorator the decorated function has to return what we expect it to return. This means the wrapper function inside the decorator must return the result of the function call. We have to make sure the wrapper function does this so the decorated function works like it should. The decorator has to return the value from the function.
So what are some real world uses of decorators?
Decorators are actually used for a lot of things, like logging and also for checking if someone has the permissions to do something. We also use decorators to see how long it takes for a function to run.. Then there is caching or memoization which is basically a way to save the results of a function so we do not have to run it again. These are some of the common use cases of decorators.
What does the Decorators in Python documentation explain?
The Decorators in Python documentation explains how decorators modify the behavior of functions or methods without changing their source code. It covers built-in decorators, custom decorators, use cases, syntax patterns, and best practices for writing reusable and readable decorators.
What is the correct Decorators in Python syntax?
The Decorators in Python syntax uses the @decorator_name symbol placed above a function definition. This syntax tells Python to wrap the function with additional functionality provided by the decorator, making the code cleaner and more readable.
How do Decorators in Python with arguments work?
Decorators in Python with arguments are decorators that accept parameters themselves. They are implemented using nested functions, where the outer function takes arguments and returns the actual decorator, allowing greater flexibility and customization.