Python Decorators and Closures 2

Question 1

What is a 'decorator factory' in Python?

Accepted Answer

A function that returns a decorator, allowing decorators to accept arguments

Answer

A decorator factory is a function that accepts arguments and returns a decorator, allowing you to create parameterized decorators.

Question 2

When multiple decorators are stacked, in what order are they applied to the function?

@decorator_A
@decorator_B
def my_func():
    pass

Accepted Answer

decorator_B first, then decorator_A

Answer

Decorators are applied bottom-up, so decorator_B is applied first, then decorator_A wraps the result, equivalent to my_func = decorator_A(decorator_B(my_func)).

Question 3

What is the purpose of the nonlocal keyword in Python closures?

Accepted Answer

To allow an inner function to modify a variable in the enclosing (non-global) scope

Answer

nonlocal allows an inner function to modify (not just read) a variable defined in its enclosing but non-global scope.

Question 4

What is a 'free variable' in the context of Python closures?

Accepted Answer

A variable used in a function but defined in an enclosing outer scope

Answer

A free variable is a variable referenced inside a function but not defined in that function's local scope — it is bound in an enclosing scope and captured by the closure.

Question 5

What attribute of a Python function object holds the free variables captured by a closure?

Accepted Answer

__closure__

Answer

The __closure__ attribute is a tuple of cell objects containing the values of variables captured by the closure, or None if the function captures no free variables.

Python Practice Test

Python Practice Test

Python Decorators and Closures 2