Question

I try to avoid having pointers, and instead of doing

std::list<std::pair<int,int>* > myList;
void addElement(int a, int b) {
    myList.push_back(new std::pair<int,int>(a,b));
}

I figured i could do something like

std::list<std::pair<int,int> > myList;
void addElement(int a, int b) { 
    std::pair<int,int> p(a,b);
    myList.push_back(p);
}

If i understand the behaviour correctly, this should store a copy of the pair, and automatically delete it when doing myList.clear() (as opposed to the pointers).

Is this the best way to do it?
Can i expect the compiler to optimize away the unnecessary object p?

Answer 1

“Can i expect the compiler to optimize away the unnecessary object p?”

Maybe, maybe not. Try this though:

myList.push_back(std::make_pair(a,b));

You usually have better chances of optimization when you work with r-values where applicable.

But even if it’s not optimized away, that is no reason to resort to using pointers, especially for such small objects(not that I would advocate using pointers for large objects). Only use pointers when they are semantically the correct thing to use, and that is rare.