Python Coding challenge - Day 1283| What is the output of the following Python Code?

 

Code Explanation:

Line 1: def dec(f):

Defines a decorator function named dec. The parameter f receives the original function that we want to modify.

Line 2: cache = {}

Creates an empty dictionary to store how many times each argument has been passed to the decorated function.

Initially:

cache = {}

Line 3: def wrap(x):

Defines an inner function named wrap. This function replaces the original function's name after the decorator is applied.

Line 4: cache[x] = cache.get(x, 0) + 1

This line updates the call count for argument x.

- cache.get(x, 0) returns the existing count, or 0 if x is not present.

- + 1 increases that count by one.

- cache[x] = saves the updated count.

For x = 3, the first call stores 3: 1; the second call updates it to 3: 2.

Line 5: return f(x) + cache[x]

Calls the original function using f(x) and adds the current count from the dictionary.

For x = 3:

- f(3) returns 3 * 2 = 6.

- On the first call, cache[3] is 1, so the result is 6 + 1 = 7.

- On the second call, cache[3] is 2, so the result is 6 + 2 = 8.

Line 6: return wrap

Returns the inner function wrap instead of executing it immediately. The dictionary remains accessible to wrap through a closure.

Line 7: @dec

Applies the decorator to calc. It is equivalent to writing:

calc = dec(calc)

After decoration, the name calc refers to the wrapper function.

Line 8: def calc(x):

Defines the original function that receives the argument x.

Line 9: return x * 2

Returns twice the value of x. For x = 3, the original function returns 6.

Line 10: print(calc(3), calc(3))

Calls the decorated function twice with the same argument, 3.

- First call returns 7.

- Second call returns 8.

- print() displays both values separated by a space.

4. Final Output

7 8

Book: 100 Python Programs for Beginner with explanation