+ virtual std::list<ObjectPtr> list() = 0;
+
+ /// Returns true if the object is in list
+ virtual bool isInList(const ObjectPtr& theObj) = 0;
+
+ /// Returns the referenced object by the zero-based index
+ ///\param theIndex zero-based index in the list
+ ///\param theWithEmpty if it is false, counts the not-empty referenced objects only
+ virtual ObjectPtr object(const int theIndex, const bool theWithEmpty = true) const = 0;
+
+ /// Substitutes the object by another one. Does nothing if such object is not found.
+ virtual void substitute(const ObjectPtr& theCurrent, const ObjectPtr& theNew) = 0;