Question

Is there any way to make a function call only once?

Suppose I have some class

struct A {

   void MainRoutine(Params) {
      // Want to call other routine only once
   }

   void OtherRoutine(Params) {
      // Do something that should be done only once and
      // what depends on the params
   }
};   

I want to call OtherRoutine only once in MainRoutine (I assume that MainRoutine is going to be called N times. I can’t call OtherRoutine from the constructor, because it accepts Params which may not be available at the time when object is being constructed.

Basically I want to do something like

static bool called = false;
if (!called) {
   OtherRoutine(Params);
   called = true;
}

but I hope there is a more “beautiful” way of doing this… (which could be written in one line)

Maybe something using boost::function or some part of boost that I don’t know about? 🙂

Thank you

Answer 1

Take a look at Boost Thread’s one-time initialization mechanism