private AType m_AProperty;

public AType AProperty {
  get {
    return m_AProperty;
  }
  set {
    if (m_AProperty == value)
    {
      m_AProperty = value; // 'value' is a keyword / magic name referring ONLY IN PROPERTY SETTERS to the given argument
      //NotifyPropertyChanged("AProperty"); // add this if you raise property changed events
    }
  }
}