关于Delphi COM编程中OleVariant类型作为参数引用的问题(300分)

在用Delphi对Lotus Sametime进行COM编程中，代码如下：

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls,ComObj, OleServer, STComTkLib_TLB;

type
TForm1 = class(TForm)
Button1: TButton;
STCommunityService: TCommunityService;

STLookupService: TLookupService;
STResolver: TResolver;
STIm: TIm;
STIMService: TInstantMessagingService;
STUser: TSTUser;
procedure Button1Click(Sender: TObject);
procedure STCommunityServiceLoggedIn(Sender: TObject;
var ev: OleVariant);
procedure FormClose(Sender: TObject; var Action: TCloseAction);
procedure STResolverResolved(Sender: TObject; var ev: OleVariant);
procedure STResolverResolveFailed(Sender: TObject; var ev: OleVariant);
private

public
{ Public declarations }


end;

var
Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
begin
STCommunityService.LoginByPassword('SametimeServer','User','password');
end;

procedure TForm1.STCommunityServiceLoggedIn(Sender: TObject;
var ev: OleVariant);
begin
ShowMessage('Login OK');

STResolver.ConnectTo(STLookupService.CreateResolver(-1,-1));
STResolver.Resolve('user2');
end;

procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
Action := caFree;
end;

procedure TForm1.STResolverResolved(Sender: TObject; var [red]ev: OleVariant[/red]);
var
iST : IResolveEvent;
evdd: OleVariant;
isu : ISTuser;
begin
ShowMessage('Resolved OK');

[red]STIMService.CreateIm(ev.GetResolvedUser,IST_ENC_LEVEL_NONE,1);[/red]

end;

procedure TForm1.STResolverResolveFailed(Sender: TObject;
var ev: OleVariant);
begin
ShowMessage('Resolved Failed');
end;

end.
在STResolver的Resolved事件中的参数ev为OleVariant类型变量，根据类型库声明：
procedure TResolver.InvokeEvent(DispID: TDispID; var Params: TVariantArray);
begin
case DispID of
-1: Exit; // DISPID_UNKNOWN
1: if Assigned(FOnResolved) then
FOnResolved(Self, Params[0] {const IResolveEvent});
2: if Assigned(FOnResolveConflict) then
FOnResolveConflict(Self, Params[0] {const IResolveEvent});
3: if Assigned(FOnResolveFailed) then
FOnResolveFailed(Self, Params[0] {const IResolveEvent});
end; {case DispID}
end;
可看出ev为IResolveEvent，其GetResolvedUser的函数作为CreateIm的参数输入，CreateIm类型库声明如下：
function TInstantMessagingService.CreateIm(const STUserObject: ISTUser; EncLevel: Integer;
ImType: Integer): IIm;

在编译过程中始终无法通过，其在VB中的实现如下：
Private Sub MyResolver_Resolved(ByVal ev As STComTkLib.IResolveEvent)
TInstantMessagingService.CreateIm ev.GetResolvedUser
UserName.SetFocus
End Sub

请教各位高手在Delphi中如何解决？谢谢！
如需涉及编程的软件环境，可于我联系。

你有没有试一下强制类型转换?

试过了，OleVariant类型无法进行类的强制转换

过程中也可以声明接口和类

only you:
如何写

到底是什么错误或原因通不过编译？
将错误信息提供看看！

如果直接使用ev：
STIMService.CreateIm(ev.GetResolvedUser,IST_ENC_LEVEL_NONE,1);
会产生：[Error] Unit1.pas(91): Incompatible types: 'Variant' and 'ISTUser'错误

如果进行类型转换：
STIMService.CreateIm(ISTUser(ev.GetResolvedUser),IST_ENC_LEVEL_NONE,1);
会产生：[Error] Unit1.pas(91): Invalid typecast错误

你的转换方式写错了。
应该类似于：
(ev as ISTUSer).GetResolvedUser