Fórum Form.release ou Action:=cafree? Qual usar? #233945

[b:1c4b74a806]procedure Free;[/b:1c4b74a806] [b:1c4b74a806]Description[/b:1c4b74a806] Use Free to destroy an object. Free automatically calls the destructor if the object reference is not nil. Any object instantiated at runtime that does not have an owner should be destroyed by a call to Free so that it can be properly disposed of and its memory released. Unlike Destroy, Free is successful even if the object is nil; so if the object was never initialized, Free won’t result in an error. When you call Free for a component, it calls Free for all components that it owns—that is, all components in its component list. Since a form owns all the controls and other components that are created on it in design mode, those components are automatically freed when the form is freed. By default, all forms are owned by the Application object; when the application terminates, it frees the Application object, which frees all forms. For objects that are not components, or for components created with a nil owner, be sure to call Free after you are finished with them; otherwise the allocated memory will not be usable until after the application terminates. Warning:Never explicitly free a component within one of its own event handlers or the event handler of a component it owns or contains. For example, don’t free a button, or the form that owns the button, in its OnClick event handler. To free a form, call its Release method, which destroys the form and releases the memory allocated for it after all its event handlers and those of the components it contains are through executing.

[b:1c4b74a806]procedure Release;[/b:1c4b74a806] [b:1c4b74a806]Description[/b:1c4b74a806] Use Release to destroy the form and free its associated memory. Release does not destroy the form until all event handlers of the form and event handlers of components on the form have finished executing. Release also guarantees that all messages in the form´s event queue are processed before the form is released. Any event handlers for the form or its children should use Release instead of Free (Delphi) or delete (C++). Failing to do so can cause a memory access error. Note:Release returns immediately to the caller. It does not wait for the form to be freed before returning.

[b:1c4b74a806]caFree : [/b:1c4b74a806]The form is closed and all allocated memory for the form is freed. ...To close the form and free it in an OnClose event, set Action to caFree.

  // Para .ShowModal

  // 1º
  Form2:= TForm2.Create(Application);
  Form2.Showmodal;
  Form2.Free;
  Form2:= nil;

  // 2º
  Application.CreateForm(TForm2,Form2);
  Form2.Showmodal;
  Form2.Free;
  Form2:= nil;

  // 3º Free e :=nil pode ser substituido por FreeAndNil
  // nos dois exemplos...
  Form2:= TForm2.Create(Application);
  Form2.Showmodal;
  FreeAndNil(Form2);

  // 4º Release tbm pode ser usado...
  Form2:= TForm2.Create(Application);
  Form2.Showmodal;
  Form2.Release;
  Form2:= nil;

  // Para .Show vc precisa trabalhar a liberação no Form2...

  // 5º
  Form2:= TForm2.Create(Application);
  Form2.Show;
  { 1º
    procedure TForm2.FormClose(Sender: TObject; var Action: TCloseAction);
    begin
      Action:= caFree;
      Form2:= nil;
    end;

    2º
    procedure TForm2.FormClose(Sender: TObject; var Action: TCloseAction);
    begin
      Release;
      Form2:= nil;
    end; }