contrib/rpl/rgrl/rgrl_command.h

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#ifndef rgrl_command_h_
#define rgrl_command_h_
//:
// \file
// \brief Base class for callback/observer method
// \author Charlene Tsai
// \date April 2004

#include <vbl/vbl_ref_count.h>
class rgrl_object;
class rgrl_event;

//: rgrl_command is an implementation of the command design pattern that is used in callbacks.
//
//  rgrl_object implements the subject. When a subject needs to notify
//  an observer, it does so using a rgrl_command. The \a execute(.)
//  method is called to run the command.
class rgrl_command: public vbl_ref_count
{
 public:
  //:
  rgrl_command() {}

  // copy constructor - compiler-provided one sets ref_count to nonzero which is wrong -PVr
  rgrl_command(rgrl_command const&) : vbl_ref_count() {}

  //:
  virtual ~rgrl_command() {}

  //: Abstract method that defines the action to be taken by the command
  virtual void execute(rgrl_object* caller, rgrl_event const& event ) = 0;

  //: Abstract method that defines the action to be taken by the command.
  //
  //  This variant is expected to be used when requests come from a
  //  const rgrl_object
  virtual void execute(const rgrl_object* caller, rgrl_event const& event ) = 0;
};

#endif