STL container assignment and const pointers

Question

This compiles:

int* p1;
const int* p2;
p2 = p1;

This does not:

vector v1;
vector v2;
v2 = v1;         


        

Answer 1

It would be perfectly possible to write your own version of vector where this was possible. It would be identical to the standard type, but with a templated version of operator=, something like this:

template 
vector2 &operator=(const vector2 &other)
{
    assign(other.begin(), other.end());
    return *this;
}

Where T is the element type of the whole class, whereas A is any type assignable to T.

It's not clear to me why std::vector doesn't have this.