Is there a way to avoid duplicated code while creating a function in rvalue and lvalue references?

Question

Sometimes when i'm creating a function it needs a rvalue reference version, as example:

template<typename T> void printCont(T &Cont){
    for (auto &i : Cont)
        cout << i << ' ';
    cout << endl;
}

So i can print any container like std::vector but i would need to manage some rvalues to be printed directly

template<typename T> void printCont(T &&Cont){
    for (auto &i : Cont)
        cout << i << ' ';
    cout << endl;
}

So i can call it as printCont(myclass.getVector()) as example. (in this example would be to easy to just copy the content to print in this version, to a lvalue vector, but in real world programs, do this would make our program slower)

But as you can see, BOTH FUNCTIONS HAVE THE SAME CODE. Is i know, duplicated code is a mistake in good practices. So my question is about... is there a way to call the lvalue version of the function from the rvalue version or viseversa? Is there a way to avoid this duplicated code? Imagine i create two 2000lines function and i need to create both version of it, it would be a waste of lines just do "Control+C" and "Control+V".

Answer 1

For the second function:

template<typename T> void printCont(T &&Cont)

it is actually a forwarding reference, which means it can be called with both lvalue and rvalue arguments. If called with an lvalue then T deduces to lvalue reference type. You can remove the first version from your code.

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Another option, since your code does not modify the operand, is to use:

template<typename T> void printCont(T const& Cont)

which also will accept both lvalues and rvalues.

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(in this example would be to easy to just copy the content to print in this version, to a lvalue vector, but in real world programs, do this would make our program slower)

This makes no sense, it seems you have some misunderstanding about lvalues and rvalues.