PCAP Closures and Decorators 2

Question 1

What is a decorator in Python?

Accepted Answer

A callable that takes a function as an argument, extends its behavior, and returns a new callable

Answer

A decorator is a higher-order function that wraps another function to add behavior before, after, or around the original call without modifying its source code.

Question 2

What is the `@my_decorator` syntax exactly equivalent to when placed above `def func(): ...`?

Accepted Answer

func = my_decorator(func)

Answer

`@my_decorator` is syntactic sugar: Python calls `my_decorator(func)` and rebinds the name `func` to whatever is returned.

Question 3

What does `@functools.wraps(func)` do when applied inside a decorator's wrapper function?

Accepted Answer

Copies the wrapped function's metadata (__name__, __doc__, __module__, etc.) onto the wrapper

Answer

`@functools.wraps(func)` preserves the original function's identity attributes on the wrapper so introspection tools and documentation generators see the correct name and docstring.

Question 4

When the following decorators are applied, in what order are they executed?

@decorator_a
@decorator_b
def func(): pass

Accepted Answer

decorator_b wraps func first (innermost), then decorator_a wraps the result (outermost)

Answer

Decorators are applied bottom-up: `decorator_b(func)` is evaluated first, and then `decorator_a` receives that result.

Question 5

What will `print(greet.__name__)` output?

import functools
def my_decorator(func):
    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        return func(*args, **kwargs)
    return wrapper

@my_decorator
def greet():
    pass

Accepted Answer

greet

Answer

Because `@functools.wraps(func)` is applied, the wrapper inherits the original function's `__name__`, so it prints `greet`.

PCAP - Certified Associate in Python Programming Practice Test

PCAP - Certified Associate in Python Programming Practice Test

PCAP Closures and Decorators 2