Python Coding challenge - Day 723| What is the output of the following Python Code?

 

Code Explanation:

1) def outer(x):

Defines a function named outer that takes one parameter x.

This is the outer function which will create and return another function.

2) def inner(y):

Inside outer, we define another function inner that takes one parameter y.

inner is a nested function and can access variables from the enclosing scope (outer).

3) return x + y

Body of inner: it returns the sum of x (from the outer scope) and y (its own argument).

Important: x is not a local variable of inner, but inner closes over it — this is the closure behavior.

4) return inner

outer returns the function object inner (not calling it).

At this moment inner carries with it the binding of x that was provided when outer was called.

5) f = outer(5)

Calls outer(5):

A new inner function is created that has x bound to 5.

That inner function object is returned and assigned to f.

So f is now a function equivalent to lambda y: 5 + y (conceptually).

6) print(f(3))

Calls the function stored in f with y = 3.

Inside that inner, x is 5 (from when outer(5) ran), so it computes 5 + 3 = 8.

print outputs:

8

7) print(outer(10)(2))

This is a one-shot call:

outer(10) creates and returns a new inner function with x bound to 10.

Immediately calling (...)(2) invokes that inner with y = 2.

Computes 10 + 2 = 12.

print outputs:

12

Final Output

8

12

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