TQCommand

class TQCommand : public TList, public TQObject

    protected:

      virtual void Init(const char* cl, void* object, const char* redo, const char* undo)

    public:

                          TQCommand(const char* cl = "0", void* object = 0, const char* redo = "0", const char* undo = "0")
                          TQCommand(TObject* obj, const char* redo = "0", const char* undo = "0")
                          TQCommand(const TQCommand& com)
                  virtual ~TQCommand()
             virtual void Add(TObject* obj, Option_t* opt)
             virtual void Add(TObject* obj)
           virtual Bool_t CanCompress(TQCommand* c) const
           virtual Bool_t CanMerge(TQCommand* c) const
           virtual Bool_t CanRedo() const
           virtual Bool_t CanUndo() const
           static TClass* Class()
             virtual void Compress(TQCommand* c)
             virtual void Delete(Option_t* option)
        static TQCommand* gCommand()
      virtual const char* GetName() const
                    Int_t GetNRargs() const
                    Int_t GetNUargs() const
                    void* GetObject() const
            TQConnection* GetRedo() const
                  Long_t* GetRedoArgs() const
              const char* GetRedoName() const
                    Int_t GetStatus() const
      virtual const char* GetTitle() const
            TQConnection* GetUndo() const
                  Long_t* GetUndoArgs() const
              const char* GetUndoName() const
          virtual TClass* IsA() const
           virtual Bool_t IsEqual(const TObject* obj) const
                   Bool_t IsExecuting() const
                   Bool_t IsMacro() const
                   Bool_t IsRedoing() const
           virtual Bool_t IsSetter() const
                   Bool_t IsUndoing() const
             virtual void ls(Option_t* option) const
             virtual void Merge(TQCommand* c)
             virtual void Print(Option_t* option) const
             virtual void Redo(Option_t* option)
             virtual void SetArgs(Int_t nargs)
             virtual void SetName(const char* name)
             virtual void SetRedoArgs(Int_t nargs)
             virtual void SetTitle(const char* title)
             virtual void SetUndoArgs(Int_t nargs)
             virtual void ShowMembers(TMemberInspector& insp, char* parent)
             virtual void Streamer(TBuffer& b)
                     void StreamerNVirtual(TBuffer& b)
             virtual void Undo(Option_t* option)

Data Members

    protected:

      TQConnection* fRedo       do/redo action
      TQConnection* fUndo       undo action
            Long_t* fRedoArgs   redo values
            Long_t* fUndoArgs   undo values
              Int_t fNRargs     number of redo arguments
              Int_t fNUargs     number of undo arguments
              Int_t fState      -1 undoing on, 1 redoing on, 0 nothing in progress
              Int_t fStatus     fStatus++ after Redo(), fStatus-- after Undo()
             Bool_t fNewDelete  kTRUE if Redo/Undo methods are new/delete
            TString fName       command name. Default is "ClassName::RedoName(args)"
            TString fTitle      command description
              void* fObject     object to which undo/redo actions applied

Class Description

                                                                      
 The Command design pattern is based on the idea, that all editing    
 in an application is done by creating instances of command objects.  
 Command objects apply changes to the edited object and then are      
 stored  on a command stack. Furthermore, each command knows how to   
 undo its changes to bring the edited object back to its previous     
 state. As long as the application only uses command objects to       
 change the state of the edited object, it is possible to undo        
 a sequence of commands by traversing the command stack downwards and 
 calling the "undo" method of each command in turn. It is also        
 possible to redo a sequence of commands by traversing the command    
 stack upwards and calling the "redo" method of each command.         
                                                                      
                                                                      
 Examples:                                                            
                                                                      
 1. Create a new command                                              
                                                                      
 TQCommand *com = new TQCommand("TH1", hpx, "SetFillColor(Color_t)"   
                                "SetFillColor(Color_t)");             
                                                                      
 1st parameter - the name of class                                    
 2nd parameter - object                                               
 3rd parameter - the name of do/redo method                           
 4th parameter - the name of undo method                              
                                                                      
 Since redo,undo methods are the same, undo name can be omitted, e.g. 
                                                                      
 TQCommand *com = new TQCommand("TH1", hpx, "SetFillColor(Color_t)"); 
                                                                      
 For objects derived from TObject class name can be omitted, e.g.     
                                                                      
    TQCommand *com = new TQCommand(hpx, "SetFillColor(Color_t)");     
                                                                      
 2. Setting undo, redo parameters.                                    
                                                                      
    Color_t old_color = hpx->GetFillColor();                          
    Color_t new_color = 4;  // blue color                             
                                                                      
    com->SetRedoArgs(1, new_color);                                   
    com->SetUndoArgs(1, old_color);                                   
                                                                      
 1st argument - the number of undo, redo parameters                   
 the other arguments - undo, redo values                              
                                                                      
 Since the number of undo,redo parameters is the same one can use     
                                                                      
    com->SetArgs(1, new_color, old_color);                            
                                                                      
 3. Undo, redo method execution                                       
                                                                      
    com->Redo(); // execute redo method                               
    com->Undo(); // execute undo method                               
                                                                      
 4. Merged commands                                                   
                                                                      
 It possible to group several commands together so an end user        
 can undo and redo them with one command.                             
                                                                      
    TQCommand *update = new TQCommand(gPad, "Modified()");            
    com->Add(update);                                                 
                                                                      
 5. Macro commands                                                    
                                                                      
 "Merging" allows to create macro commands, e.g.                      
                                                                      
    TQCommand *macro = new TQCommand("my macro");                     
    macro->Add(com1);                                                 
    macro->Add(com2);                                                 
    ...                                                               
                                                                      
 During Redo operation commands composing macro command are executed  
 sequentially in direct  order (first in first out). During Undo,     
 they are executed in reverse order (last in first out).              
                                                                      
 6. Undo manager.                                                     
                                                                      
 TQUndoManager is recorder of undo and redo operations. This is       
 command history list which can be traversed backwards and upwards    
 performing undo and redo operations.                                 
 To register command TQUndoManager::Add(TObject*) method is used.     
                                                                      
    TQUndoManager *history = new TQUndoManager();                     
    history->Add(com);                                                
                                                                      
 TQUndoManager::Add automatically invokes execution of command's      
 Redo method.                                                         
                                                                      
 Use TQUndoManager::Undo to undo commands in  history list.           
 Redo is Undo for undo action. Use TQUndoManager::Redo method for that
                                                                      

 common protected method used in several constructors

 Constructor.

   Input parameters:
     1. clname - class name.
     2. obj - an object
     3. redo - method or function to do/redo operation
     4. undo - method or function to undo operation

 Comments:
    - if either clname or obj is NULL that means that redo/undo is function
    - to specify default arguments for redo/undo method/function
       '=' must precede to argument value.

  Example:
    TQCommand("TPad", gPad, "SetEditable(=kTRUE)", "SetEditable(=kFALSE)");

    - undo method can be same as redo one. In that case undo parameter
       can be omitted.

  Example:
    TQCommand("TPad", gPad, "SetFillStyle(Style_t)");

 Constructor.

   Input parameters:
     1. obj - an object
     2. redo - method or function to do/redo operation
     3. undo - method or function to undo operation

 Comments:
    - to specify default arguments for redo/undo method/function
       '=' must precede to argument value.

  Example:
    TQCommand(gPad, "SetEditable(=kTRUE)", "SetEditable(=kFALSE)");

    - undo method can be same as redo one. In that case "undo"
       can parameter be omitted.

  Example:
    TQCommand(gPad, "SetFillStyle(Style_t)");

 Copy constructor.

 dtor.

 Return a command which is doing redo/undo action

 This static method allows to set undo parameters dynamically, i.e.
 during execution of Redo function.

 Example:
    For redo actions like TGTextEdit::DelChar() it is not possible to
    know ahead what character will be deleted.
    To set arguments for undo action ( e.g. TGTextEdit::InsChar(char)),
    one needs to call TQCommand::SetUndoArgs(1, character) from
    inside of TGTextEdit::DelChar() method, i.e.

    TQCommand::gCommand()->SetUndoArgs(1, somechar);

 If "opt" is not zero delete every merged command which option string is
 equal to "opt". If "opt" is zero - delete all merged commands.

 Two commands can be merged if they can be composed into
 a single command (Macro command).

 To allow merging commands user might override this function.

 Add command to the list of merged commands.
 This make it possible to group complex actions together so an end user
 can undo and redo them with one command. Execution of TQUndoManager::Undo(),
 TQUndoManager::Redo() methods only invokes the top level command as a whole.

 Merge method is analogous to logical join operation.

 Note:  Merge method invokes redo action.

 Add command to the list of merged commands.

 Option string can contain substrings:
  "compress" - try to compress input command
  "radd" - execute redo action of input command
  "uadd" - execute undo action of input command

 By default, commands can be compressed if they are:

  - equal
  - setter commands

 More complicated commands might want to override this function.

 Compress command. Compression is analogous to arithmetic "addition operation".

 Note:
    - The compressed command will be deleted.
    - Execution Compress method invokes Redo action with new redo arguments
      inheritied from compressed command.

 More complicated commands might want to override this function.

 Equal comparison. The commands are equal if they are
 applied to the same object and have the same Redo/Undo actions

 More complicated commands might want to override this function.

 Returns kTRUE is command if Redo is the same as Undo function
 and is the setter action.

 By default, all functions with names like "SetXXX" or "setXXX"
 considered as setters. Another type of setters are Move, Resize operations

 More complicated commands might want to override this function.

 Set do/redo and undo parameters. The format is
    SetArgs(number_of_params, redo_params, undo_params)

 Example:
     move_command->SetArgs(2, 100, 100, 200, 200);
      2 params, (100,100) - do/redo position, (200,200) - undo position

 Set redo parameters. The format is
    SetRedoArgs(number_of_params, params)

 Example:
     move_command->SetRedoArgs(2, 100, 100);

 Set undo parameters. The format is
    SetUndoArgs(number_of_params, params)

 Example:
     move_command->SetUndoArgs(2, 200, 200);

 Returns kTRUE if Redo action is possible, kFALSE if it's not.
 By default, only single sequential redo action is possible.

 Returns kTRUE if Undo action is possible, kFALSE if it's not.
 By default, only single tial undo action is possible.

 Execute command and then smerged commands

 Unexecute all merged commands and the command.
 Merged commands are executed in reverse order.

 Returns the command name. Default name is "ClassName::RedoName(args)"
 If list of merged commands is not empty the name is
 "ClassName::RedoName(args):cname1:cname2 ..."

 Returns command description.
 By default, "ClassName::RedoName(args)_ClassName::UndoName(args)"

 Returns the name of redo command

 Returns the name of undo command

 Returns a pointer to array of redo arguments

 Returns a pointer to array of undo arguments

 Returns a number of redo arguments

 Returns a number of undo arguments

 Returns an object for which undo redo acions are applied

 Returns a number of sequential undo or redo operations

 Returns kTRUE if neither redo nor undo action specified

 Undo action is in progress

 Redo action is in progress

 Returns kTRUE if command execution is in progress

 Sets name of the command

 Sets description of the command

 ls this command and merged commands

 print this command and all merged commands

Inline Functions

        TQConnection* GetRedo() const
        TQConnection* GetUndo() const
                 void Add(TObject* obj)
              TClass* Class()
              TClass* IsA() const
                 void ShowMembers(TMemberInspector& insp, char* parent)
                 void Streamer(TBuffer& b)
                 void StreamerNVirtual(TBuffer& b)