Delphi里可将纯虚类实例化，还可调用非虚函数

这是与Java/C++的巨大不同。目前还没仔细想这个特征与TClass之间的联系，先记住结论再说。以后再回来修改这个帖子。

unit Unit1;

interface

uses

Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

Dialogs, StdCtrls;

type

TForm1 = class(TForm)

Button1: TButton;

procedure Button1Click(Sender: TObject);

private

{ Private declarations }

public

{ Public declarations }

end;

TXXX = class(TObject)

private

FList: TList;

protected

function PeekItem: Pointer; virtual; abstract;

property List: TList read FList;

public

constructor Create;

destructor Destroy; override;

procedure Show;

end;

var

Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);

VAR

x: TXXX;

begin

x:=TXXX.Create; // 实例化一点问题没有

x.PeekItem; // 调用纯虚方法出错 // 调用Show方法正确执行

end;

{ TXXX }

constructor TXXX.Create;

begin

inherited;

end;

destructor TXXX.Destroy;

begin

inherited;

end;

procedure TXXX.Show;

begin

ShowMessage('dddd');

end;

end.