如何调用名称存储在字符串中的方法？

Question

uses Windows, System.SysUtils, Dialogs, ActiveX, ComObj, Variants, WinSvc; 

function PerformWMISelectQuery(ASelectQuery: string): string; 
var 
    _objWMIService: OLEVariant; 
    _colItems: OLEVariant; 
    _colItem: OLEVariant; 
    _oEnum: IEnumvariant; 
    _iValue: Longword; 
    _Field: string; 
    function GetWMIObject(const objectName: string): IDispatch; 
    var 
    _chEaten: Integer; 
    _BindCtx: IBindCtx; 
    _Moniker: IMoniker; 
    begin 
    try 
     OleCheck(CreateBindCtx(0, _BindCtx)); 
     OleCheck(MkParseDisplayName(_BindCtx, StringToOleStr(objectName), 
     _chEaten, _Moniker)); 
     OleCheck(_Moniker.BindToObject(_BindCtx, nil, IDispatch, Result)); 
    except 
     on E: Exception do 
     MessageDlg(E.Message, TMsgDlgType.mtError, [TMsgDlgBtn.mbOK], 0); 
    end; 
    end; 

begin 
    Result := ''; 
    { check if service is running } 
    begin 
    try 
     if (Copy(UpperCase(ASelectQuery), 0, 6) <> 'SELECT') or 
     (Pos('FROM', UpperCase(ASelectQuery)) = 0) or 
     (Pos(',', ASelectQuery) <> 0) then 
     raise Exception.Create('Illegal query: ' + ASelectQuery) 
     else 
     begin 
     // get field name 
     _Field := Copy(ASelectQuery, 8, 
      Pos(' ', Copy(ASelectQuery, 8, (Length(ASelectQuery)))) - 1); 
     _objWMIService := GetWMIObject('winmgmts:\\localhost\root\cimv2'); 
     _colItems := _objWMIService.ExecQuery(ASelectQuery, 'WQL', 0); 
     _oEnum := IUnknown(_colItems._NewEnum) as IEnumvariant; 
     if _oEnum.Next(1, _colItem, _iValue) = 0 then 
     begin 
      Result := VarToStr(_colItem._Field); // Error here 
     end; 
     end; 
    except 
     on E: Exception do 
     MessageDlg(E.Message, TMsgDlgType.mtError, [TMsgDlgBtn.mbOK], 0); 
    end; 
    end; 
end; 

用法：

ShowMessage(PerformWMISelectQuery('SELECT name FROM Win32_Bios')); 

给我：方法_Field“没有自动化对象支持

，如果你改变

Result := VarToStr(_colItem._Field); 

到

Result := VarToStr(_colItem.name); 

它的工作

所以，我的问题是，如何在这里使用字符串作为方法名？ 谢谢。

Answer 1

访问的SWbemObject对象的属性，你必须使用SWbemObject.Properties_财产

所以从

Result := VarToStr(_colItem._Field); 

改变你的代码要

Result := VarToStr(_colItem.Properties_.item(_Field));