1 unit Unit2;
 2 
 3 interface
 4 
 5 uses System.SysUtils;
 6 
 7 type
 8   { TSingle }
 9   TSingle = class(TObject)
10   private
11     FStr: string;
12   protected
13   public
14     constructor Create;
15     class function GetInstance(): TSingle;
16     class function NewInstance: TObject; override;
17     procedure FreeInstance; override;
18 
19     property Str: string read FStr write FStr;
20   published
21 
22   end;
23 
24 implementation
25 
26 var
27   GlobalSingle: TSingle;
28   { TSingle }
29 constructor TSingle.Create;
30 begin
31   FStr := DateTimeToStr(Now);
32 end;
33 
34 procedure TSingle.FreeInstance;
35 begin
36   inherited;
37   GlobalSingle := nil;
38 end;
39 
40 class function TSingle.GetInstance: TSingle;
41 begin
42   if not Assigned(GlobalSingle) then
43   begin
44     GlobalSingle := TSingle.Create();
45   end;
46   Result := GlobalSingle;
47 end;
48 
49 class function TSingle.NewInstance: TObject;
50 begin
51   if not Assigned(GlobalSingle) then
52     GlobalSingle := TSingle(inherited NewInstance);
53   Result := GlobalSingle;
54 end;