请问这种类型的变量如何赋值？(50分)

type
TtdCompareFunc = function (aData1, aData2 : pointer) : integer;
TtdDisposeProc = procedure (aData : pointer);
TtdUpcaseFunc = function(aCh : AnsiChar) : AnsiChar;
TtdVisitProc = procedure (aData : pointer;
aExtraData : pointer;
var aStopVisits : boolean);
请给个例子。

unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs;
type
TtdCompareFunc = function (aData1, aData2 : pointer) : integer;
TForm1 = class(TForm)
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
Execute : TtdCompareFunc;//定义变量
end;

var
Form1: TForm1;
implementation
{$R *.dfm}
{ TForm1 }
function Test(aData1, aData2: pointer): integer;//具体的函数
begin
//
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
Execute := Test;//赋值
end;

end.

多谢！祝新年快乐！