To support move semantics, should function parameters be taken by unique_ptr, by value, or by rvalue?

Question

One of my function takes a vector as a parameter and stores it as a member variable. I am using const reference to a vector as described below.

class Test {
         


        

Answer 1

The current advice on this is to take the vector by value and move it into the member variable:

void fn(std::vector val)
{
  m_val = std::move(val);
}

And I just checked, std::vector does supply a move-assignment operator. If the caller doesn't want to keep a copy, they can move it into the function at the call site: fn(std::move(vec));.