Delphi 接口统一方法

unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;
type
IDemo=interface
function A(i:Integer):Integer;
end;

type
TDemo=class(TInterfacedObject,IDEmo)
public
function A(i:Integer):Integer;
end;

type
TDemob=class(TInterfacedObject,IDEmo)
public
function A(i:Integer):Integer;
end;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{ TDemo }

function TDemo.A(i: Integer): Integer;
begin
 ShowMessage('TDemo _'+inttostr(i));
end;

{ TDemob }

function TDemob.A(i: Integer): Integer;
begin
 ShowMessage('TDemob _'+inttostr(i));
end;

procedure TForm1.Button1Click(Sender: TObject);
var
Demob:TDemob;
Demo:TDemo;
vIDemo:IDemo;
begin
 Demo:=TDemo.Create;
 Demob:=TDemob.Create;


 vIDemo:=IDemo(Demo);
 vIDemo.A(1);


 vIDemo:=IDemo(Demob);
 vIDemo.A(2);

end;

end.