Last Updated : 11 Jul, 2025
Prerequisite: Decorators in Python, Function Decorators
We know Decorators are a very powerful and useful tool in Python since it allow programmers to modify the behavior of functions or classes. In this article, we will learn about the Decorators with Parameters with the help of multiple examples.
Python functions are First Class citizens which means that functions can be treated similarly to objects.
Decorators with parameters are similar to normal decorators.
@decorator(params)
def func_name():
''' Function implementation'''
The above code is equivalent to
def func_name():
''' Function implementation'''
func_name = (decorator(params))(func_name)
"""
As the execution starts from left to right decorator(params) is called which returns a function object fun_obj. Using the fun_obj the call fun_obj(fun_name) is made. Inside the inner function, required operations are performed and the actual function reference is returned which will be assigned to func_name. Now, func_name() can be used to call the function with a decorator applied to it.
How Decorator with parameters is implemented
Python3
def decorators(*args, **kwargs):
def inner(func):
'''
do operations with func
'''
return func
return inner #this is the fun_obj mentioned in the above content
@decorators(params)
def func():
"""
function implementation
"""
Here params can also be empty.
Observe these first :
Python3
# Python code to illustrate
# Decorators basic in Python
def decorator_fun(func):
print("Inside decorator")
def inner(*args,**kwargs):
print("Inside inner function")
print("Decorated the function")
# do operations with func
func()
return inner()
@decorator_fun
def func_to():
print("Inside actual function")
func_to
Inside decorator Inside inner function Decorated the function Inside actual function
Another Way:
Python3
# Python code to illustrate
# Decorators with parameters in Python
def decorator_fun(func):
print("Inside decorator")
def inner(*args, **kwargs):
print("Inside inner function")
print("Decorated the function")
func()
return inner
def func_to():
print("Inside actual function")
# another way of using decorators
decorator_fun(func_to)()
Inside decorator Inside inner function Decorated the function Inside actual function
Let's move to another example:
Example 1:
Here is the code Explaination
decorator(like): The decorator function now directly accepts the parameter like.inner(func): This function wraps the actual function func and uses the parameter like within its scope.wrapper(): The wrapper function is used to call the actual func, and it is returned from the inner function.
# Python code to illustrate
# Decorators with parameters in Python
def decorator(like):
print("Inside decorator")
def inner(func):
# code functionality here
print("Inside inner function")
print("I like", like)
def wrapper():
func()
return wrapper
# returning inner function
return inner
@decorator(like="geeksforgeeks")
def my_func():
print("Inside actual function")
# Call the decorated function
my_func()
Inside decorator Inside inner function I like geeksforgeeks Inside actual function
Example 2:
Here is the code Explaination
decorator_func(x, y): This is a decorator factory. It takes two parameters, x and y, and returns a decorator.Inner(func): This is the actual decorator returned by decorator_func. It takes a function func and defines a wrapper function around it.wrapper(*args, **kwargs): This function is executed when the decorated function is called. It prints some messages and the summation of x and y before calling the original function func.return wrapper: The wrapper function is returned by the Inner function.return Inner: The Inner decorator is returned by decorator_func.decorator_func(12, 15)(my_fun)('Geeks', 'for', 'Geeks'): This line applies the decorator with the parameters 12 and 15 to my_fun. The decorator prints the message and summation before calling my_fun with the arguments 'Geeks', 'for', 'Geeks'.
# Python code to illustrate
# Decorators with parameters in Python
def decorator_func(x, y):
def Inner(func):
def wrapper(*args, **kwargs):
print("I like Geeksforgeeks")
print("Summation of values - {}".format(x+y) )
func(*args, **kwargs)
return wrapper
return Inner
# Not using decorator
def my_fun(*args):
for ele in args:
print(ele)
# another way of using decorators
decorator_func(12, 15)(my_fun)('Geeks', 'for', 'Geeks')
I like Geeksforgeeks Summation of values - 27 Geeks for Geeks
Example 3:
Here is the code Explaination
type_check_decorator:
expected_type specifies the type that all arguments should be.decorator: Takes the function func to be decorated.wrapper: Checks if all arguments are of expected_type and calls func if they are; otherwise, returns "Invalid Input".string_join: Joins all string arguments into one string.summation: Sums up all integer arguments.string_join("I ", 'like ', "Geeks", 'for', "geeks"): Concatenates strings correctly.summation(19, 2, 8, 533, 67, 981, 119): Sums integers correctly.
# Simple decorator with parameters
def type_check_decorator(expected_type):
def decorator(func):
def wrapper(*args, **kwargs):
if all(isinstance(arg, expected_type) for arg in args):
return func(*args, **kwargs)
return "Invalid Input"
return wrapper
return decorator
@type_check_decorator(str)
def string_join(*args):
return ''.join(args)
@type_check_decorator(int)
def summation(*args):
return sum(args)
# Test the functions
print(string_join("I ", 'like ', "Geeks", 'for', "geeks"))
print(summation(19, 2, 8, 533, 67, 981, 119))
I like Geeksforgeeks 1729
1. Inside the Decorator
2. Inside the function
Note: Image snapshots are taken using PythonTutor.
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