Python Decorators: Adding Magic to Your Functions, One Layer at a Time

What Exactly is a Decorator?

A decorator in Python is a powerful tool that allows you to wrap extra functionality around an existing function. Think of it as putting an extra layer of “awesome” on a function, without actually changing the original code.

How Decorators Work

A decorator is simply a function that takes another function as input, adds some extra functionality, and returns a new function.

Example:

<span>def</span> <span>shout</span><span>(</span><span>func</span><span>):</span>
    <span>def</span> <span>wrapper</span><span>():</span>
        <span>return</span> <span>func</span><span>().</span><span>upper</span><span>()</span>
    <span>return</span> <span>wrapper</span>
<span>@shout</span>
<span>def</span> <span>greet</span><span>():</span>
    <span>return</span> <span>"</span><span>hello</span><span>"</span>
<span>print</span><span>(</span><span>greet</span><span>())</span>  <span># Outputs: HELLO </span>
<span>def</span> <span>shout</span><span>(</span><span>func</span><span>):</span>
    <span>def</span> <span>wrapper</span><span>():</span>
        <span>return</span> <span>func</span><span>().</span><span>upper</span><span>()</span>
    <span>return</span> <span>wrapper</span>

<span>@shout</span>
<span>def</span> <span>greet</span><span>():</span>
    <span>return</span> <span>"</span><span>hello</span><span>"</span>

<span>print</span><span>(</span><span>greet</span><span>())</span>  <span># Outputs: HELLO </span>
def shout(func):
    def wrapper():
        return func().upper()
    return wrapper

@shout
def greet():
    return "hello"

print(greet())  # Outputs: HELLO 

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Here, the @shout decorator transforms greet() so it returns its output in uppercase.

Common Use Cases for Decorators

Decorators are handy for adding cross-cutting functionalities to functions, like:

• Logging: Automatically logging whenever a function is called.
• Authentication: Checking permissions before running sensitive functions.
• Timing: Measuring how long a function takes to run.

Stacking Decorators

Yes, you can stack multiple decorators to apply multiple layers of functionality to a single function.

<span>@authenticate</span>
<span>@log</span>
<span>def</span> <span>process_data</span><span>(</span><span>data</span><span>):</span>
    <span># Function code </span>
<span>@authenticate</span>
<span>@log</span>
<span>def</span> <span>process_data</span><span>(</span><span>data</span><span>):</span>
    <span># Function code </span>
@authenticate
@log
def process_data(data):
    # Function code 

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This runs authenticate first, then log, and finally process_data.

Final Words: Decorators—Your Function’s Best Friend

Decorators let you add power to your code without clutter. They’re your shortcut to clean, reusable, and enhanced functions.

🥂 Here’s to functions that do more, without the mess!”

原文链接：Python Decorators: Adding Magic to Your Functions, One Layer at a Time