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Python Decorators Explained

bookChaining Multiple Decorators


              
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def bold_decorator(func):
    def wrapper(*args, **kwargs):
        return "<b>" + func(*args, **kwargs) + "</b>"
    return wrapper

def italic_decorator(func):
    def wrapper(*args, **kwargs):
        return "<i>" + func(*args, **kwargs) + "</i>"
    return wrapper

@bold_decorator
@italic_decorator
def greet():
    return "Hello!"

print(greet())
# Output: <b><i>Hello!</i></b>
copy

When you chain multiple decorators on a single function, Python applies them from the closest decorator to the function outward, but executes them in the reverse order. In the provided example, @italic_decorator is applied to greet first, then @bold_decorator wraps the result. This means that when you call greet(), the call first goes through bold_decorator, which then calls the version of greet that has already been wrapped by italic_decorator. As a result, the output is enclosed first in <i>...</i>, then in <b>...</b>, producing <b><i>Hello!</i></b>. Understanding this order is crucial when combining multiple decorators, as the sequence can affect the final behavior and output of your function.

question-icon

Fill in the blanks to show the correct order in which decorators are applied and executed.

  • What should go in the blanks ___A___ and ___B___ so that "First decorator" is printed before "Second decorator" when calling say_hi()?

  • Type your answers as: first_decorator, second_decorator

  • A:

  • B:

,
First decorator
Second decorator
Hi!

Click or drag`n`drop items and fill in the blanks

Everything was clear?

How can we improve it?

Thanks for your feedback!

SectionΒ 2. ChapterΒ 2

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bookChaining Multiple Decorators

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1234567891011121314151617

            
def bold_decorator(func):
    def wrapper(*args, **kwargs):
        return "<b>" + func(*args, **kwargs) + "</b>"
    return wrapper

def italic_decorator(func):
    def wrapper(*args, **kwargs):
        return "<i>" + func(*args, **kwargs) + "</i>"
    return wrapper

@bold_decorator
@italic_decorator
def greet():
    return "Hello!"

print(greet())
# Output: <b><i>Hello!</i></b>
copy

When you chain multiple decorators on a single function, Python applies them from the closest decorator to the function outward, but executes them in the reverse order. In the provided example, @italic_decorator is applied to greet first, then @bold_decorator wraps the result. This means that when you call greet(), the call first goes through bold_decorator, which then calls the version of greet that has already been wrapped by italic_decorator. As a result, the output is enclosed first in <i>...</i>, then in <b>...</b>, producing <b><i>Hello!</i></b>. Understanding this order is crucial when combining multiple decorators, as the sequence can affect the final behavior and output of your function.

question-icon

Fill in the blanks to show the correct order in which decorators are applied and executed.

  • What should go in the blanks ___A___ and ___B___ so that "First decorator" is printed before "Second decorator" when calling say_hi()?

  • Type your answers as: first_decorator, second_decorator

  • A:

  • B:

,
First decorator
Second decorator
Hi!

Click or drag`n`drop items and fill in the blanks

Everything was clear?

How can we improve it?

Thanks for your feedback!

SectionΒ 2. ChapterΒ 2
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