When is the use of std::ref necessary?

Question

Consider:

std::tuple func (const A& a) 
{
  return std::make_tuple( 0 , std::ref(a) );
}

Is the std::re

Answer 1

• make_tuple(0, a) makes a tuple.
• make_tuple(0, ref(a)) makes a tuple>.
• You can also say tuple t(0, a); for a tuple you can't make with make_tuple, or use std::tie.