PRODUCT  :  C++                                    NUMBER  :  652
  VERSION  :  All
       OS  :  PC DOS
     DATE  :  September 17, 1991                       PAGE  :  1/1

    TITLE  :  Interrupt Handlers as Member Functions




  An  interrupt  handler  cannot  be  made  a  static member  of  a
  class because  there is no way  to  pass such a function a 'this'
  pointer.  It is possible, however, to overcome this difficulty by
  creating  a  static  member  function  that is given access to  a
  pointer to the class that is currently active. For example:

         class ISR {
           public:
             static void interrupt handler();
             ISR *active;
             void handle();
         };

         void interrupt ISR::handler() {
           active->handle();
         }

  In this example,  ISR::handler()  is installed as the handler and
  active must be set to point to a valid instance of ISR.