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[wxWidgets.git] / docs / latex / wx / objectdataptr.tex

\section{\class{wxObjectDataPtr<T>}}\label{wxobjectdataptr}

This is helper template class to avoid memleaks because of missing calls
to \helpref{wxObjectRefData::DecRef}{wxobjectrefdatadecref}.

Despite the name this template can actually be used for any
class implementing the reference counting interface and it
does not use or depend on wxObject.

\wxheading{See also}

\helpref{wxObject}{wxobject},
\helpref{wxObjectRefData}{wxobjectrefdata},
\helpref{Reference counting}{trefcount}

\wxheading{Derived from}

No base class

\wxheading{Include files}

<object.h>

\wxheading{Data structures}

{\small%
\begin{verbatim}
typedef T element_type
\end{verbatim}
}%

\wxheading{Example}

\begin{verbatim}

// include file

class MyCarRefData: public wxObjectRefData
{
public:
    MyCarRefData()  { m_price = 0; }
    
    MyCarRefData( const MyCarRefData& data )
        : wxObjectRefData()
    {
        m_price = data.m_price;
    }

    bool operator == (const MyCarRefData& data) const
    {
        return m_price == data.m_price;
    }
    
    void SetPrice( int price )  { m_price = price; }
    int GetPrice()              { return m_price; }
    
protected:
    int m_price;
};

class MyCar
{
public:
    MyCar( int price );
    MyCar( const MyCar& data );
    
    bool operator == ( const MyCar& car ) const;
    bool operator != (const MyCar& car) const { return !(*this == car); }

    void SetPrice( int price );
    int GetPrice() const;

    wxObjectRefPtr<MyCarRefData> m_data;
    
protected:
    void UnShare();
};


// implementation

MyCar::MyCar( int price )
{
    m_data = new MyCarRefData;
    m_data.get()->SetPrice( price );
}

MyCar::MyCar( const MyCar& car )
{
    m_data.reset( car.m_data.get() );
}

bool MyCar::operator == ( const MyCar& car ) const
{
    if (m_data.get() == car.m_data.get()) return true;

    return (*m_data.get() == *car.m_data.get());
}

void MyCar::SetPrice( int price )
{
    UnShare();
        
    m_data.get()->SetPrice( price );
}

int MyCar::GetPrice() const
{
    return m_data.get()->GetPrice();
}

void MyCar::UnShare()
{
    if (m_data.get()->GetCount() == 1)
        return;
    
    m_data.reset( new MyCarRefData( *m_data.get() ) );
}

\end{verbatim}


\latexignore{\rtfignore{\wxheading{Members}}}

\membersection{wxObjectDataPtr<T>::wxObjectDataPtr<T>}\label{wxobjectdataptrwxobjectdataptr}

\func{wxEXPLICIT}{wxObjectDataPtr<T>}{\param{T* }{ptr = NULL}}

Constructor. {\it ptr} is a pointer to the reference
counted object to which this class points.

\func{}{wxObjectDataPtr<T>}{\param{const wxObjectDataPtr<T>\& }{tocopy}}

This copy constructor increases the count of the reference
counted object to which {\it tocopy} points and then this
class will point to, as well.

\membersection{wxObjectDataPtr<T>::\destruct{wxObjectDataPtr<T>}}\label{wxobjectdataptrdtor}

\func{}{\destruct{wxObjectDataPtr<T>}}{\void}

Calls \helpref{DecRef}{wxobjectrefdatadecref} on the reference
counted object to which this class points.

\membersection{wxObjectDataPtr<T>::operator->}\label{wxobjectdataptroperatorpointer}

\constfunc{T*}{operator->}{\void}

Gets a pointer to the reference counted object to which
this class points. Same as \helpref{get}{wxobjectdataptrget}.

\membersection{wxObjectDataPtr<T>::operator=}\label{wxobjectdataptroperatorassign}

\func{wxObjectDataPtr<T>\& operator}{operator=}{\param{const wxObjectDataPtr<T>\& }{tocopy}}

\func{wxObjectDataPtr<T>\& operator}{operator=}{\param{T* }{ptr}}

Assignment operators.

\membersection{wxObjectDataPtr<T>::get}\label{wxobjectdataptrget}

\constfunc{T*}{get}{\void}

Gets a pointer to the reference counted object to which
this class points.

\membersection{wxObjectDataPtr<T>::reset}\label{wxobjectdataptrreset}

\func{void}{reset}{\param{T* }{ptr}}

Reset this class to {\it ptr} which points to a reference
counted object.