unit Unitfile;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Button4: TButton;
    Memo1: TMemo;
    Label1: TLabel;
    Edit1: TEdit;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure Button4Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

  INumberClass = Interface(IUnknown)
    procedure SetValue(NewValue:Integer);
    function GetValue:Integer;
    procedure Increase;
  end;

  TNumberClass = class(TInterfacedObject,INumberClass)
  public
    Value:Integer;
    procedure SetValue(NewValue:Integer);
    function GetValue:Integer;
    procedure Increase;
    destructor Destroy;override;
  end;

var
  Form1: TForm1;
  MyInterface:INumberClass;

implementation

{$R *.dfm}

{ TNumberClass }

destructor TNumberClass.Destroy;
begin
  ShowMessage('資源已釋放！');
  inherited;
end;

function TNumberClass.GetValue: Integer;
begin
   Result := Value;
end;

procedure TNumberClass.Increase;
begin
  Value := Value + 1;
end;

procedure TNumberClass.SetValue(NewValue: Integer);
begin
   Value := NewValue;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  MyInterface.SetValue(StrToInt(Edit1.Text));
  Memo1.Lines.Append('數值已設置！');
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  Memo1.Lines.Append('現在的數值為：'+IntToStr(MyInterface.GetValue));
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
  MyInterface.Increase;
  Memo1.Lines.Append('數值加1后為：'+IntToStr(MyInterface.GetValue));

end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  MyInterface := TNumberClass.Create;
end;

procedure TForm1.Button4Click(Sender: TObject);
begin
  Application.Terminate;
end;

end.