RWModel(3C++)

Name
     RWModel - Rogue Wave library class

Synopsis
              #include <rw/model.h>



              (abstract base class)




Description
     This abstract base class has been designed to implement the "Model" leg
     of a Model-View-Controller architecture.  A companion class,
     RWModelClient, supplies the "View" leg. It maintains a list of dependent
     RWModelClient objects.  When member function changed(void*) is called,
     the list of dependents will be traversed, calling updateFrom(RWModel*,
     void*) for each one, with itself as the first argument.  Subclasses of
     RWModelClient should be prepared to accept such a call.

Persistence
     None

Example
     This is an incomplete and somewhat contrived example in that it does not
     completely define the classes involved.  "Dial" is assumed to be a
     graphical representation of the internal settings of "Thermostat."  The
     essential point is that there is a dependency relationship between the
     "Thermostat" and the "Dial": when the setting of the thermostat is
     changed, the dial must be notified so that it can update itself to
     reflect the new setting of the thermostat.

              #include <rw/model.h>



              class Dial : public RWModelClient {
          public:
            virtual void     updateFrom(RWModel* m, void* d);
          };


              class Thermostat : public RWModel {



                double setting;
          public:
            Thermostat( Dial* d )
              { addDependent(d); }
            double temperature() const
              { return setting; }
            void setTemperature(double t)
              { setting = t; changed(); }
          };


              void Dial::updateFrom(RWModel* m, void*) {



                Thermostat* t = (Thermostat*)m;
            double temp = t->temperature();
            // Redraw graphic.
          }

Public Constructor
              RWModel();


     When called by the specializing class, sets up the internal ordered list
     of dependents.

Public Member Functions
              void
          addDependent(RWModelClient* m);


     Adds the object pointed to by m to the list of dependents of self.

              void
          removeDependent(RWModelClient* m);


     Removes the object pointed to by m from the list of dependents of self.

              virtual void
          changed(void* d);


     Traverse the internal list of dependents, calling member function
     updateFrom(RWModel*, void*) for each one, with self as the first argument
     and d as the second argument.