EventedProperty.h

#ifndef __EVENTEDPROPERTY_H__221ADEB0_5C31_4bfe_872F_73B16AB08F75
#define __EVENTEDPROPERTY_H__221ADEB0_5C31_4bfe_872F_73B16AB08F75

#include "EventHandler.h"

template<typename DATATYPE>
class CPropertyChangedEventArgs: public OIL::CEventHandlerArgs
{
protected:
    DATATYPE m_OldValue;
    DATATYPE m_NewValue;
public:
    template<typename OLDVALTYPE, typename NEWVALTYPE>
    CPropertyChangedEventArgs(const OLDVALTYPE& oldVal, const NEWVALTYPE& NewVal)
        : m_OldValue(oldVal), m_NewValue(NewVal)
    {
    }
    inline const DATATYPE& OldValue() const {   return m_OldValue;  }
    inline const DATATYPE& NewValue() const {   return m_NewValue;  }
};

template<typename DATATYPE>
class CPropertyChangingEventArgs: public CPropertyChangedEventArgs<DATATYPE>
{
    bool     m_bCancel;
public:
    template<typename OLDVALTYPE, typename NEWVALTYPE>
    CPropertyChangingEventArgs(const OLDVALTYPE& oldVal, const NEWVALTYPE& NewVal)
        : CPropertyChangedEventArgs<DATATYPE>(oldVal, NewVal), m_bCancel(false)
    {       
    }
    inline bool Cancel() const  {   return m_bCancel;   }
    inline void SetCancel()     {   m_bCancel = true;   }
};

template<typename DATATYPE>
class CEventedProperty : public OIL::CEventSource
{
    DATATYPE m_Data;
public:
    typedef CEventedProperty<DATATYPE> thisClass;

    typedef OIL::CEventT<CEventedProperty<DATATYPE>,  CPropertyChangingEventArgs<DATATYPE> > PropertyChangingEvent;
    typedef OIL::CEventT<CEventedProperty<DATATYPE>,  CPropertyChangedEventArgs<DATATYPE> > PropertyChangedEvent;

    PropertyChangingEvent ValueChanging;
    PropertyChangedEvent ValueChanged;

    CEventedProperty()  {}

    template<typename T>
    CEventedProperty(const T& InitVal): m_Data(InitVal) {}

    inline operator DATATYPE() const    {   return m_Data;  }

    template<typename T>
    inline CEventedProperty& operator =(const T& other) 
    {   
        CPropertyChangingEventArgs<DATATYPE> evArgs(m_Data, other);
        RaiseEvent(&ValueChanging, &evArgs);

        if(evArgs.Cancel() == false)
        {
            CPropertyChangedEventArgs<DATATYPE> ChangedEvArgs(m_Data,other); //Not to Loose Old Data we first create the EvArgs obj
            m_Data = other;
            RaiseEvent(&ValueChanged, &ChangedEvArgs);
        }

        return *this;
    }
};

#endif