How can I “override” [] to accept two arguments in C++?

Question

I am trying to create a bit-vector class in C++ to model some hardware. In most HDLs (hardware description langauges) that I know, specific bits are referenced like this:

Answer 1

a simple struct with two members as a parameter to operator[]...

struct pos
{
  int lsb;
  int msb;
};

pos foo={1,2};

my_vector[foo];

or in the new standard, I believe you can simply do:

my_vector[pos{1,2}]