Création d'un callback de tâche (task)

Un callback de tâche est une tâche déclenchée par la fin de l'exécution d'une autre tâche.

Tip : Un callback doit être enregistré, une fois suffit.

Exemple :

unit TestSYFREWF;
interface
 
Type
  TestTaskCallBack = Class(TitTask)
  public
    Function Execute():boolean;
    Procedure RegisterCallBack;
    Procedure UnRegister;
  end;
 
Implementation
 
{TestTaskCallBack}
 
Function TestTaskCallBack.Execute():boolean;
//Function Execute():boolean;
var idx:Integer; S:string; aMsg:TdbmQueueMessage;
begin
  Result := True;
 
  // Add messages to the log
  ProgressMessage('On TestTask Terminate');
 
  if Assigned(UserContext.TaskContext) and Assigned(userContext.TaskContext.EventContext) then
   begin
     userContext.TaskContext.AddMessage('Has Task context');
     //
     aMsg := userContext.TaskContext.EventContext.ReceivedMsg;
     if Assigned(aMsg) then
      begin
        userContext.TaskContext.AddMessage(Format('Task reference: %s',[aMsg.ValueByNames(':message.source.reference')]));
        userContext.TaskContext.AddMessage(Format('Message parameters count:%d',[aMsg.Count]));
        for idx:=0 to aMsg.Count-1 do
         begin
           S := aMsg.DisplayStrings(idx);
           UserContext.TaskContext.AddMessage(S);
         end;
      end;
   end
   else ProgressMessage('no task context');
 
  Result := True;
end;
 
Procedure TestTaskCallBack.RegisterCallBack;
//Procedure RegisterCallBack;
var aReason:string;
begin
  if not SubscribeToEvent(TTestTask.OnTerminateSuccessID(),aReason) then
   showMessage('subscribe failed '+aReason); 
end;
 
Procedure TestTaskCallBack.UnRegister;
//Procedure UnRegister;
var aReason:string;
begin
  if not UnSubscribeFromEvent(TTestTask.OnTerminateSuccessID(),aReason) then
   showMessage(aReason); 
end;
 
end.

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