Python function: from where does it get value?

Question

def f(a, x): # a.x=2, x=3
return a.x + x # 5
class A:
def f(self, x): # input x = 2
self.x = x # a.x property = 2
return x + 1 # 2+1=3

a = A() # x not yet exists, a = obj
y = f(a, a.f(2)) # after comma: 3
print(y) # output = 5

When debugging this SL challenge, I found that a = 2 in the FIRST LINE. Anyone to explain why? I have commented the code for easier understanding.

Answer 1

y = f(a, a. f(2))
calls method f of a and assigns 2 to attribute x

That is done before calling free function f.

Answer 2

at the moment you call the free function f
a has an attribute x=2.
So first parameter is a with a. x = 2.
2nd parameter is a.f(2) which has a kind of side effect.
It a) returns 3
and b) assigns 2 to a.x

inner before outer, so assignment is done before calling free f.

Answer 3

Oma Falk Now it is clear. I have missed side effect “b”. Thanks again and have a great day!

Answer 4

Oma Falk Thanks! You have helped me clarifying my question.

What is not clear for me: calling function f here

y = f(a, a.f(2))

... assigns 2 to “a.x” and not to “a”.

In the first line, the function f gets “a” attribute and not a.x

This is my real question.

Answer 5

ok but it uses a.x fir return