delphi – 为什么在通过元类类工厂实例化时不会调用派生的构造函

我找到了一些很好的参考资料,例如How can I create an Delphi object from a class reference and ensure constructor execution?,但我仍然无法让它工作得很好.在下面的测试中,我无法让它调用派生构造函数,即使调试器告诉我oClass是TMyDerived.

我觉得我对这里的一些基本内容感到困惑,可以使用一些解释.谢谢.

program ClassFactoryTest;
{$APPTYPE CONSOLE}
uses
  SysUtils;

//  BASE CLASS
type
  TMyBase = class(TObject)
    bBaseFlag : boolean;
    constructor Create; virtual;
  end;
  TMyBaseClass = class of TMyBase;

constructor TMyBase.Create;
begin
  bBaseFlag := false;
end;

//  DERIVED CLASS
type
  TMyDerived = class(TMyBase)
    bDerivedFlag : boolean;
    constructor Create;
  end;

constructor TMyDerived.Create;
begin
  inherited;
  bDerivedFlag := false;
end;

var
  oClass: TMyBaseClass;
  oBaseInstance,oDerivedInstance: TMyBase;
begin
  oClass := TMyBase;
  oBaseInstance := oClass.Create;

  oClass := TMyDerived;
  oDerivedInstance := oClass.Create;  // <-- Still calling Base Class constructor
end.