C++ tie one variable to two others via references

Question

In C++, we can define a variable by reference like:

int foo = 3;
int &bar = foo;

Then, the following code

cout << foo << " " << bar;

will print

3 3

because the "value" of bar is tied to the value of foo by reference(&). I'm wondering, is there a way to tie the value of "bar" to two variables? Say I have three variables: geddy, neil, and alex, and I want neil to always equal alex + geddy. Is there a way two write something like:

int alex = 4;
int geddy = 5;
int &neil = alex + geddy;

So that neil will return 9? Then, if I change alex to 7, neil will return 12?

Answer 1

No, not really. You could make a function or functor though:

int alex = 4;
int geddy = 5;

auto neil = [&]() { return alex + geddy; };
std::cout << neil() << "\n";