Delphi中Class of

---------开发环境Delphi7 ----------

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效果图：

----Unit开始

unit Unit1;

interface

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

type
  TSysButton=class of Tbutton;
  TMyCustomerButton=class(TButton) //声明一个TMyCustomerButton类  Tbutton第一代继承’人‘
  private
    FStr:string;
  end;
  TMyButton= class of TMyCustomerButton; //声明一个类引用类型(类的类)，具体啥的请搜一下

  TMyCustomerButton02=class(TMyCustomerButton) //Tbutton第二代继承’人‘
  private
    FStr02:string;
  end;

  TMyCustomerButton03=class(TMyCustomerButton02) //Tbutton第三代继承’人‘
  private
    FStr03:string;
  end;

  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    Procedure MyCreateButton(AOwner:TWinControl; AClass:TSysButton);  //AClass:TMyButton 这个也可以的
    { Private declarations }
  public
    { Public declarations }
  end;
var
  Form1: TForm1;
implementation

var
  i:Integer=1;

{$R *.dfm}
{ TForm1 }
procedure TForm1.MyCreateButton(AOwner: TWinControl ; AClass:TSysButton); //AClass:TMyButton 这个也可以的
var
  vButton:TButton;
begin
  vButton:=AClass.Create(AOwner);
  vButton.Parent:=AOwner;
  vButton.Left :=100;
  vButton.Top :=10+30*(i-1);
  vButton.height:=20;
  vButton.Width:=80;
  vButton.Name:='MyButton_'+inttostr(i);
  Inc(i);
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  {从这里可以看出，不管是TButton的第几代继承‘人’，
  都能创建该继承人类型的Button出来
  }
  //把这个TMyCustomerButton(Tbutton第一代继承人)传过去，就能创建TMyCustomerButton类型的Button出来
  //MyCreateButton(Self,TMyCustomerButton); //这里把类型(TMyCustomerButton)传过去了
  //MyCreateButton(Self,TMyCustomerButton02); //这里把类型(TMyCustomerButton02)传过去了
  MyCreateButton(Self,TMyCustomerButton03); //这里把类型(TMyCustomerButton03)传过去了
end;

procedure TForm1.Button2Click(Sender: TObject);
var
  vButton:TMyCustomerButton; //vButton:TMyCustomerButton02; vButton:TMyCustomerButton03
begin
  vButton:=TMyCustomerButton(FindComponent('MyButton_1')); //vButton:=TMyCustomerButton02(FindComponent('MyButton_1'))
  if vButton<>nil then
  begin
    vButton.FStr:='FStr_MyButton_1'; //TMyCustomerButton、TMyCustomerButton02、TMyCustomerButton03都有FStr，02和03是继承来的
    ShowMessage(vButton.FStr);
  end;
end;

end.

---Unit结束 

----------Form开始

object Form1: TForm1
  Left = 755
  Top = 481
  Width = 239
  Height = 269
  Caption = 'Form1'
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'MS Sans Serif'
  Font.Style = []
  OldCreateOrder = False
  PixelsPerInch = 96
  TextHeight = 13
  object Button1: TButton
    Left = 8
    Top = 0
    Width = 75
    Height = 25
    Caption = 'Button1'
    TabOrder = 0
    OnClick = Button1Click
  end
  object Button2: TButton
    Left = 8
    Top = 64
    Width = 75
    Height = 25
    Caption = 'Button2'
    TabOrder = 1
    OnClick = Button2Click
  end
end

-------Form结束