https://www.cnblogs.com/del/archive/2009/10/13/1582789.html
class helper may be from Delphi 2007 added new syntax, because the feeling is not practical, until today only test it.
After tried to know:! Very interesting basic function is to modify the existing class.
Txxx = class helper for T ... { T ... } represents the existing classes
{existing methods may alternatively}
{new method may also be members}
End;
When re-using a T ... // class and its descendant classes after this, will give priority to the use of modified Txxx.
Example One:
Unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;
type
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
end;
TMyClass = class
function func1: string;
function func2: string;
end;
Helper class for TMyClass = TMyClassHelper
function func1: String; {will replace the same method on TMyClass swap}
function func3: String; {will increase its subclasses the methods TMyClass}
End;
was
Form1 TForm1;
implementation
{$R *.dfm}
{ TMyClass }
function TMyClass.func1: string;
begin
Result := 'TMyClass.func1';
end;
function TMyClass.func2: string;
begin
Result := 'TMyClass.func2';
end;
{ TMyClassHelper }
function TMyClassHelper.func1: string;
begin
Result := 'TMyClassHelper.func1';
end;
function TMyClassHelper.func3: string;
begin
Result := 'TMyClassHelper.func3';
end;
//测试
procedure TForm1.Button1Click(Sender: TObject);
var
obj: TMyClass;
begin
obj := TMyClass.Create;
ShowMessage(obj.func1); {TMyClassHelper.func1}
ShowMessage(obj.func2); {TMyClass.func2}
ShowMessage(obj.func3); {TMyClassHelper.func3}
obj.Free;
end;
end.
Example Two: This Example TControl increased to a class method, after TControl and all of its descendants will have this method.
Unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;
type
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
end;
TMyClassHelper = class helper for TControl
procedure MyMsg;
end;
was
Form1 TForm1;
implementation
{$R *.dfm}
{ TMyClassHelper }
TMyClassHelper.MyMsg Procedure;
the begin
ShowMessageFmt ( 'class name is% s% s', [the Name, ClassName]);
End;
@ Test: This test current button and the current form, they are inherited from the TControl
Procedure TForm1.Button1Click (Sender: TObject);
the begin
Self.MyMsg; the Form1 {} class name TForm1
the TButton (Sender). MyMsg; {Button1 class name} TButton1
End;
end.
