Simulating nested functions in C++

Local functions are not allowed in C++, but local classes are and function are allowed in local classes. So:

int foo( int foo_var )
{
 /*code*/
  struct local 
  {
    static int bar( int bar_var )  
    {
      /*code*/
      return bar_var;
    }
  };
  return local::bar(foo_var);
}

In C++0x, you would also have the option of creating a functor using lambda syntax. That's a little more complicated in C++03, but still not bad if you don't need to capture variables:

int foo( int foo_var )
{
 /*code*/
  struct bar_functor
  {
    int operator()( int bar_var )  
    {
      /*code*/
      return bar_var;
    }
  } bar;
  return bar(foo_var);
}

Turn your function into a functor as Herb Sutter suggests in this article