尝试在Delphi中访问OleVariant的变量操作异常无效 - 在C#中工作

Question

我正在尝试访问来自ActiveX库的回调中的OleVariant.

以下是在TLB中定义事件处理程序的内容:

procedure(ASender: TObject; var structQSnap: {??structVTIQSnap}OleVariant) of object;

这是TLB中structVTIQSnap的定义:

structVTIQSnap = packed record
  bstrSymbol: WideString;
  bstrListingExch: WideString;
  bstrLastExch: WideString;
  fLastPrice: Double;
  nLastSize: Integer;
  bstrBbo: WideString;
  bstrBidExch: WideString;
  fBidPrice: Double;
  nBidSize: Integer;
  bstrAskExch: WideString;
  fAskPrice: Double;
  nAskSize: Integer;
  fHighPrice: Double;
  fLowPrice: Double;
  fOpenPrice: Double;
  fClosePrice: Double;
  nCumVolume: Integer;
  bstrTradeCondition: WideString;
  nQuoteCondition: Integer;
  bstrCompanyName: WideString;
  f52WeekHigh: Double;
  f52WeekLow: Double;
  fEps: Double;
  nSharesOutstanding: Integer;
  nSpCode: Integer;
  fBeta: Double;
  bstrExDivDate: WideString;
  nDivFreq: Integer;
  fDivAmt: Double;
  nAvgVolume: Integer;
  bstrCusip: WideString;
  fVwap: Double;
  bstrUpdateTime: WideString;
  bstrExch: WideString;
  nSharesPerContract: Integer;
end;

它编译得很好,但每次我尝试访问bstrSymbol时,我都会得到一个"Invalid Variant Operation":

 procedure TForm1.HandleVTIQuoteSnap(ASender: TObject; var structQSnap: OleVariant);
 var
    symbol: WideString;
 begin
    symbol := structQSnap.bstrSymbol; // this line causes the exception
 end;

如何在Delphi中访问structQSnap及其属性？

在C#中,此函数适用于事件处理程序:

    void vtiQ_OnVTIQSnap(ref vtiLib.structVTIQSnap structQSnap)
    {
        MessageBox.Show("Got qsnap for " + structQuoteSnap.bstrSymbol);            
    }

有任何想法吗？

Answer 1

我认为Delphi的ActiveX导入向导不知道如何正确处理structVTIQSnap类型(这似乎是一个记录),只使用默认的OleVariant.在生成的..._ TLB.pas文件中是否有一个名为structVTIQSnap或类似的类型声明？尝试使用它而不是OleVariant,例如

procedure (ASender: TObject; var structQSnap: structVTIQSnap) of object;

该类型可能会被声明为"打包记录".