Ok. I have a class.

Qt Code: 
  1. class Material : public QObject
  2.         {
  3.             public:
  4.                 Material(QObject *parent = 0);
  5.  
  6.            protected:
  7.                 int m_count;
  8.                 QString m_fisName;
  9.                 QString m_fisCode;
  10.                 QString m_name;
  11.                 QString m_nameAux;
  12.         };
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I made a typedef

Qt Code: 
  1. typedef QList<Material> MaterialList;
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I have another class

Qt Code: 
  1. class RegularOrder : public Order
  2.         {
  3.             public:
  4.                 RegularOrder(QObject *parent = 0);
  5.  
  6.                 void TwinList(MaterialList twinList);
  7.                 void P3110List(MaterialList p3110List);
  8.                 void CPSList(MaterialList cpsList);
  9.                 void KernList(MaterialList kernList);
  10.                 void BurhList(MaterialList burhList);
  11.                 void ManualList(MaterialList manualList);
  12.  
  13.             protected:
  14.                 QList<Template> m_templateList;
  15.                 int m_currentTemplateIndex;
  16.  
  17.                 UseFlag m_listFlag;
  18.                 int m_listCount;
  19.                 QString m_deliveryWhole;
  20.  
  21.                 MaterialList m_twinList;
  22.                 MaterialList m_p3110List;
  23.                 MaterialList m_cpsList;
  24.                 MaterialList m_kernList;
  25.                 MaterialList m_burhList;
  26.                 MaterialList m_manualList;
  27.  
  28.                 QList<JobProperties> m_jobPropertiesList;
  29.         };
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which is so far implemented like this

Qt Code: 
  1. RegularOrder::RegularOrder(QObject *parent) : Order(parent)
  2.         {
  3.         }
  4.  
  5.         void RegularOrder::TwinList(MaterialList twinList)
  6.         {
  7.             m_twinList = twinList;
  8.         }
  9.  
  10.         void RegularOrder::P3110List(MaterialList p3110List)
  11.         {
  12.             m_p3110List = p3110List;
  13.         }
  14.  
  15.         void RegularOrder::CPSList(MaterialList cpsList)
  16.         {
  17.             m_cpsList = cpsList;
  18.         }
  19.  
  20.         void RegularOrder::KernList(MaterialList kernList)
  21.         {
  22.             m_kernList = kernList;
  23.         }
  24.  
  25.         void RegularOrder::BurhList(MaterialList burhList)
  26.         {
  27.             m_burhList = burhList;
  28.         }
  29.  
  30.         void RegularOrder::ManualList(MaterialList manualList)
  31.         {
  32.             m_manualList = manualList;
  33.         }
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When I try to compile I get the following messages:

/home/ivan/Development/Qt/Radni Nalog/WorkOrder/woidl.cpp:1: In file included from woidl.cpp:1:
/home/ivan/Development/Qt/Radni Nalog/WorkOrder/woidl.h:14: instantiated from ‘void QList<T>::node_copy(QList<T>::Node*, QList<T>::Node*, QList<T>::Node*) [with T = Telekom::WorkOrder::Material]’
/home/ivan/Development/Qt/Radni Nalog/WorkOrder/woidl.h:14: instantiated from ‘void QList<T>::node_copy(QList<T>::Node*, QList<T>::Node*, QList<T>::Node*) [with T = Telekom::WorkOrder::Material]’
/home/ivan/Development/Qt/Radni Nalog/WorkOrder/woidl.h:14: instantiated from ‘void QList<T>::node_copy(QList<T>::Node*, QList<T>::Node*, QList<T>::Node*) [with T = Telekom::WorkOrder::Material]’
/home/ivan/Development/Qt/Radni Nalog/WorkOrder/woidl.h:14: instantiated from ‘void QList<T>::node_copy(QList<T>::Node*, QList<T>::Node*, QList<T>::Node*) [with T = Telekom::WorkOrder::Material]’
/home/ivan/Development/Qt/Radni Nalog/WorkOrder/woidl.h:14: instantiated from ‘void QList<T>::node_copy(QList<T>::Node*, QList<T>::Node*, QList<T>::Node*) [with T = Telekom::WorkOrder::Material]’

Basically the compile stops at the m_twinList = twinList line of code. I read somewhere that QObject can't be used as a reference and copied as normal because of something but honestly didn't understand it completely.

I solved the problem by removing the inheritance of QObject in Material class. I made it independent. Now I only sort of needed that because I could make some other object a parent of the material class instances so I would have to worry about deleting it. My program will work just fine with out this parenting because only RegularOrder class will be instantiated and only RegularOrder class will need a parent to look after it. But could somebody explain to me what exactly happened here so I know for the future.

Thanks.