c++ setter/getter does not work as expected - c++

Question

for some reason my prof insists I have to use setter/getter everywhere.
Well... in this linked list I don't understand why this one doesn't work
#include <iostream>
#include <string>
using namespace std;
class SomeClass{
string some_string;
public:
void setSomeString(string s);
string getSomeString();
};
void SomeClass::setSomeString(string s){
some_string = s;
}
string SomeClass::getSomeString(){
return some_string;
}
class Node{
SomeClass some_class;
Node *next;
public:
void setSomeClass(SomeClass sc);
SomeClass getSomeClass();
//...
};
void Node::setSomeClass(SomeClass sc){
some_class = sc;
}
SomeClass Node::getSomeClass(){
return some_class;
}
class List{
public:
Node *head, *ptr;
//...
};
int main(){
List l;
l.head = new Node();
l.head->getSomeClass().setSomeString("a string");
cout << l.head->getSomeClass().getSomeString();
return 0;
}
I expect in the output "a string", instead is empty... What am I doing wrong?

Answer 1

Node::getSomeClass() method returns something by value. This means that the returned object is a copy which means that now you have two different objects and there is no side effect.
If you want to edit the original value you need to return it by reference:
SomeClass& getSomeClass() {...}
In this way you will get the reference of the original object and you can edit it.

Answer 2

Don't wrap something if wrapper adds nothing to wrapped like SomeClass adds nothing to string except useless set/get.
Even if Node::getSomeClass() returns by reference why it's private in Node? If private member returned by reference it can be abused outside of Node.
If you insist to make SomeClass private in Node then l.head->getSomeClass().setSomeString("a string") should be l.head->setSomeString("a string") where:
void Node::setSomeString(string input){
some_class.setSomeString(input); //while not exposing some_class at all
}