[PyQt] Inconsistent behavior with multiple inheritance and ConvertToSubClassCode

[Nyall Dawson]

Hi list,

I've been struggling for a while with some inconsistent behavior
relating to ConvertToSubClassCode and a multiple inherited class.

The definition currently looks something like:


class LayoutItem : LayoutObject, QGraphicsRectItem
{
%TypeHeaderCode
#include "layoutitem.h"
#include "layoutitempicture.h"
#include "layoutitemlabel.h"
%End
%ConvertToSubClassCode
    // the conversions have to be static, because they're using
multiple inheritance
    // (seen in PyQt4 .sip files for some QGraphicsItem classes)
    switch ( sipCpp->type() )
    {
      case QGraphicsItem::UserType + 104:
        sipType = sipType_LayoutItemPicture;
        *sipCppRet = static_cast<LayoutItemPicture *>( sipCpp );
        break;
      case QGraphicsItem::UserType + 105:
        sipType = sipType_LayoutItemLabel;
        *sipCppRet = static_cast<LayoutItemLabel *>( sipCpp );
        break;
      default:
        sipType = 0;
    }
%End
  public:
     ...


While this... sometimes... works correctly, most often LayoutItem
subclasses are not automatically cast to the subclass, and remain as
LayoutItems only. Is the ConvertToSubClassCode incorrect here?

Nyall