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TObjectStack.OwnsObjects Property

Get or set object ownership.

Pascal
property OwnsObjects: Boolean;
C++
__property Boolean OwnsObjects;

OwnsObjects gets or sets whether objects in the stack are owned by the stack or not. If entries are owned, when an entry object is removed from the stack, the entry object is freed. Create initializes this property.  

Delphi Examples: 

 

{
This example demonstrates the usage of the generic TObjectStack class.
}
type
  { Declare a new object type }
  TNewObject = class
  private
    FName: String;

  public
    constructor Create(const AName: String);
    destructor Destroy(); override;
  end;

{ TNewObject }

constructor TNewObject.Create(const AName: String);
begin
  FName := AName;
end;

destructor TNewObject.Destroy;
begin
  { Show a message whenever an object is destroyed }
  MessageDlg('Object "' + FName + '" was destroyed!', mtInformation, [mbOK], 0);
  inherited;
end;

procedure TForm3.Button1Click(Sender: TObject);
var
  Stack: TObjectStack<TNewObject>;
  Button: TButton;
begin
  { Create a new stack }
  Stack := TObjectStack<TNewObject>.Create();

  { Set the OwnsObjects to true - the stack will free them automatically }
  Stack.OwnsObjects := true;

  { Push some items up the stack }
  Stack.Push(TNewObject.Create('One'));
  Stack.Push(TNewObject.Create('Two'));
  Stack.Push(TNewObject.Create('Three'));

  {
    Pop an instance of TNewObject class. Destructor
    show be called because we have set the OwnsObjects
    to true!
  }
  Stack.Pop();

  { Destroy the stack completely - more messageboxes will be shown }
  Stack.Free;
end;

 

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