VkAction(3x)

NAME
     VkAction - Supports encapsulation of a command that can be undone

HEADER FILE
     #include <Vk/VkAction.h>

PUBLIC PROTOCOL SUMMARY
   Constructor/Destructor
           VkAction(const char*);
           virtual void ~VkAction(void);


   Executing actions
          void execute(void);


PROTECTED PROTOCOL SUMMARY
   Specifying do/undo Behavior
           virtual void doit(void);
           virtual void undoit(void);


   Protected Data Members
          char* _name;


CLASS DESCRIPTION
          This class supports applications that wish to model undoable actions
          as objects. Applications must create derived classes that define the
          exact actions to be taken. Applications use classes derived from
          VkAction by instantiating an instance of a class and calling the
          object's execute() member function. The object automatically
          registers itself with the application's undo manager, which provides
          the interface for undoing the command.



DERIVING SUBCLASSES
          To use this class, an application must create a derived class for
          every type of action it wishes to perform. Each derived class must
          override the virtual functions doit() and undoit(). The derived
          class can add data members to maintain any state required between
          doing the command and undoing the command.



FUNCTION DESCRIPTIONS
   doit()
          virtual void doit(void);
          This virtual function should be overridden to provide the action to
          be performed by the derived class.

   undoit()
          virtual void undoit(void);


          This virtual function should be overridden to reverse the effects of
          the action performed by the derived class.

   VkAction()
          VkAction(const char* name);


          Initialize a VkAction object.

   ~VkAction()
          virtual void ~VkAction(void);


          Handle destruction of a VkAction object.

   execute()
          void execute(void);


          Calls derived classes' doit() method and arranges for the undo
          action to be registered with the undo manager.

DATA MEMBER DESCRIPTIONS
   _name
          char* _name;


          Every action should have a name, which is used to identify the
          action in the undo manager.

CLASSES USED BY THIS CLASS
     VkMenuUndoManager

SEE ALSO
     VkMenuUndoManager
     ViewKit Programmer's Guide
     The X Window System, DEC Press, Bob Sheifler and Jim Gettys
     The X Window System Toolkit, DEC Press, Paul Asente and Ralph Swick
     The OSF/Motif Programmers Reference, Prentice Hall, OSF