public Teacher[] GetTeachers(MasterData masterData) => GetTs <Teacher>(masterData, ElementType.TEACHER);
public Subject[] GetSubjects(MasterData masterData) => GetTs <Subject>(masterData, ElementType.SUBJECT);
public Class[] GetClasses(MasterData masterData) => GetTs <Class>(masterData, ElementType.CLASS);
public Room[] GetRooms(MasterData masterData) => GetTs <Room>(masterData, ElementType.ROOM);
// is: {standard: true}
// rights: ["READ_HOMEWORK"]
// can: {requestStudents: false, requestLessonTopic: false, submitLessonTopic: false}
private T[] GetTs <T>(MasterData masterData, ElementType tType)
{
return(Elements.Where(e => e.ElementType == tType).Select(e => (T)masterData.GetElement(tType, e.ElementId)).ToArray());
}