Decorators in Python are essentially functions that add functionality to an existing function in Python without changing the structure of the function itself. They are represented the @decorator_name in Python and are called in a bottom-up fashion. For example:
# decorator function to convert to lowercase
def lowercase_decorator(function):
def wrapper():
func = function()
string_lowercase = func.lower()
return string_lowercase
return wrapper
# decorator function to split words
def splitter_decorator(function):
def wrapper():
func = function()
string_split = func.split()
return string_split
return wrapper
@splitter_decorator # this is executed next
@lowercase_decorator # this is executed first
def hello():
return 'Hello World'
hello() # output => [ 'hello' , 'world' ]
The beauty of the decorators lies in the fact that besides adding functionality to the output of the method, they can even accept arguments for functions and can further modify those arguments before passing it to the function itself. The inner nested function, i.e. 'wrapper' function, plays a significant role here. It is implemented to enforce encapsulation and thus, keep itself hidden from the global scope.
# decorator function to capitalize names
def names_decorator(function):
def wrapper(arg1, arg2):
arg1 = arg1.capitalize()
arg2 = arg2.capitalize()
string_hello = function(arg1, arg2)
return string_hello
return wrapper
@names_decorator
def say_hello(name1, name2):
return 'Hello ' + name1 + '! Hello ' + name2 + '!'
say_hello('sara', 'ansh') # output => 'Hello Sara! Hello Ansh!'