以前只知道delphi解决静态函数的方法是在函数前加class
我也一直深信static不能是 override virtual abstract,但是今天看到一个帖子,突然头大了http://topic.csdn.net/u/20110827/16/cf1b0a13-7f55-4201-af6c-7dbc0c3da93d.html帖子中的代码如下
unit Unit1;interfaceuses
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; TBaseClass = class
public
class procedure ClassFun; virtual;
end; TBClass2 = class(TBaseClass)
public
class procedure ClassFun; override;
end; TBClass3 = class(TBaseClass)
public
class procedure ClassFun; override;
end; TClassRef = class of TBaseClass;var
Form1: TForm1;implementation{$R *.dfm}procedure TForm1.Button1Click(Sender: TObject);
var
c: TClassRef;
begin
ShowMessage('Call TBClass2 >>>');
c := TBClass2;
c.ClassFun;
//TBClass2.ClassFun; ShowMessage('Call TBClass3 >>>');
c := TBClass3;
c.ClassFun;
end;{ TBaseClass }class procedure TBaseClass.ClassFun;
begin
ShowMessage('TBaseClass');
end;{ TBClass2 }class procedure TBClass2.ClassFun;
begin
inherited;
ShowMessage('TBClass2');
end;{ TBClass3 }class procedure TBClass3.ClassFun;
begin
inherited;
ShowMessage('TBClass3');
end;end.以上代码看过之后糊涂了,有人能帮忙解释一下么?为啥delphi里的class静态机制可以是virtual和override甚至是abstract的?
我也一直深信static不能是 override virtual abstract,但是今天看到一个帖子,突然头大了http://topic.csdn.net/u/20110827/16/cf1b0a13-7f55-4201-af6c-7dbc0c3da93d.html帖子中的代码如下
unit Unit1;interfaceuses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;type
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end; TBaseClass = class
public
class procedure ClassFun; virtual;
end; TBClass2 = class(TBaseClass)
public
class procedure ClassFun; override;
end; TBClass3 = class(TBaseClass)
public
class procedure ClassFun; override;
end; TClassRef = class of TBaseClass;var
Form1: TForm1;implementation{$R *.dfm}procedure TForm1.Button1Click(Sender: TObject);
var
c: TClassRef;
begin
ShowMessage('Call TBClass2 >>>');
c := TBClass2;
c.ClassFun;
//TBClass2.ClassFun; ShowMessage('Call TBClass3 >>>');
c := TBClass3;
c.ClassFun;
end;{ TBaseClass }class procedure TBaseClass.ClassFun;
begin
ShowMessage('TBaseClass');
end;{ TBClass2 }class procedure TBClass2.ClassFun;
begin
inherited;
ShowMessage('TBClass2');
end;{ TBClass3 }class procedure TBClass3.ClassFun;
begin
inherited;
ShowMessage('TBClass3');
end;end.以上代码看过之后糊涂了,有人能帮忙解释一下么?为啥delphi里的class静态机制可以是virtual和override甚至是abstract的?
静态是执行时不允许动态选择实际的方法来
含义还是有一点点不同的
其实前一阵子看到过一篇delphi的文章
ecause Delphi not provide static member for our using, so if you want a static
member of class in Delphi what should I do
Ok! At least there are three ways to implement this.
1,Using private global variant(in implement section of unit),but there are a lit
visibility scope in project or unit.
2,Using global variant, a more visibility scope in project or unit.a lit same as
above.
3,Using typed constant,just using compiler directive $J+ or Project properties
|compiler Option Typed constant.
但是仅仅是介绍如何使用,对于原理一点也没有说明,所以有些糊涂
Delphi中的类方法是有Self的,而Self就是类本身(注意不是对象),
而这个Self就是通过EAX寄存器传递的在新版本的Delphi(Pascal)语法中,加入了static关键字修饰的类方法。
这东西才与C++类中的static方法类似比如在(Delphi XE)中,如下写法
例如:
TBaseClass = class
public
class procedure ClassFun; virtual;
class procedure StaticClassFun; static;
end;StaticClassFun才是你所理解的形式,StaticClassFun 是不能再用virtual dynamic修饰的