unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  end;

  {此接口声明了一个 Name 属性; 因为接口没有字段, read/write 都只能从方法}
  IMyInterface = interface
    function GetName : string;
    procedure SetName(val : string);
    property Name : string read GetName write SetName;
  end;

  {类实现的是接口的读写方法, 属性还是属于接口的; 类可以提供一个储存属性的字段}
  TMyClass = class(TInterfacedObject, IMyInterface)
  private
    FName: string;
  public
    function GetName: string;
    procedure SetName(val: string);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{ TMyClass }

function TMyClass.GetName: string;
begin
  Result := FName;
end;

procedure TMyClass.SetName(val: string);
begin
  FName := val;
end;

{ TForm1 }

procedure TForm1.Button1Click(Sender: TObject);
var
  c: TMyClass;
  i: IMyInterface;
begin
  c := TMyClass.Create;
  i := c;
  i.Name := 'ABC';
  ShowMessage(i.Name); {ABC}

  //没有一个 c.Name 存在, 这个属性只属于接口
end;

end.