Tutorial Interfaces

[DeddyH]

Exakt, ich habe da mal schnell ein Beispiel gebaut (ich habe die Standard-Benennung einfach beibehalten, da die Komponenten eh keinen tieferen Sinn haben):

Delphi-Quellcode:

unit Unit6;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;

type
  IDisplay = interface
    ['{B515DBE1-9D0E-4491-BEE8-85805852870B}']
    function DisplayString: string;
  end;

  TEdit = class(VCL.StdCtrls.TEdit, IDisplay)
  public
    function DisplayString: string;
  end;

  TLabel = class(VCL.StdCtrls.TLabel, IDisplay)
  public
    function DisplayString: string;
  end;

  TComboBox = class(VCL.StdCtrls.TComboBox, IDisplay)
  public
    function DisplayString: string;
  end;

  TWuppdi = class
    procedure Consume(const Display: IDisplay);
  end;

  TForm6 = class(TForm)
    Edit1: TEdit;
    ComboBox1: TComboBox;
    Label1: TLabel;
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
  private
    { Private-Deklarationen }
    FWuppdi: TWuppdi;
  public
    { Public-Deklarationen }
  end;

var
  Form6: TForm6;

implementation

{$R *.dfm}

{ TEdit }

function TEdit.DisplayString: string;
begin
  Result := Text;
end;

{ TLabel }

function TLabel.DisplayString: string;
begin
  Result := Caption;
end;

{ TComboBox }

function TComboBox.DisplayString: string;
begin
  if ItemIndex > -1 then
    Result := Items[ItemIndex]
  else
    Result := '';
end;

{ TWuppdi }

procedure TWuppdi.Consume(const Display: IDisplay);
begin
  ShowMessage(Display.DisplayString);
end;

procedure TForm6.Button1Click(Sender: TObject);
begin
  FWuppdi.Consume(Edit1);
end;

procedure TForm6.Button2Click(Sender: TObject);
begin
  FWuppdi.Consume(ComboBox1);
end;

procedure TForm6.Button3Click(Sender: TObject);
begin
  FWuppdi.Consume(Label1);
end;

procedure TForm6.FormCreate(Sender: TObject);
begin
  FWuppdi := TWuppdi.Create;
end;

procedure TForm6.FormDestroy(Sender: TObject);
begin
  FWuppdi.Free;
end;

end.