docs/latex/wx/objectdataptr.tex

   1 \section{\class{wxObjectDataPtr<T>}}\label{wxobjectdataptr}
   2
   3 This is helper template class primarily written to avoid memory
   4 leaks because of missing calls to \helpref{wxObjectRefData::DecRef}{wxobjectrefdatadecref}.
   5
   6 Despite the name this template can actually be used as a
   7 smart pointer for any class implementing the reference
   8 counting interface and it does not use or depend on wxObject.
   9
  10 The difference to \helpref{wxSharedPtr}{wxsharedptr} is that
  11 wxObjectDataPtr relies on the reference counting to be in
  12 the class pointed to where as wxSharedPtr implements the
  13 reference counting itself.
  14
  15 \wxheading{See also}
  16
  17 \helpref{wxObject}{wxobject},
  18 \helpref{wxObjectRefData}{wxobjectrefdata},
  19 \helpref{Reference counting}{trefcount}
  20
  21 \helpref{wxSharedPtr}{wxsharedptr},
  22 \helpref{wxScopedPtr}{wxscopedptrtemplate},
  23 \helpref{wxWeakRef}{wxweakref}
  24
  25
  26 \wxheading{Derived from}
  27
  28 No base class
  29
  30 \wxheading{Include files}
  31
  32 <object.h>
  33
  34 \wxheading{Data structures}
  35
  36 {\small%
  37 \begin{verbatim}
  38 typedef T element_type
  39 \end{verbatim}
  40 }%
  41
  42 \wxheading{Example}
  43
  44 \begin{verbatim}
  45
  46 class MyCarRefData: public wxObjectRefData
  47 {
  48 public:
  49     MyCarRefData()  { m_price = 0; }
  50
  51     MyCarRefData( const MyCarRefData& data )
  52         : wxObjectRefData()
  53     {
  54         m_price = data.m_price;
  55     }
  56
  57     void SetPrice( int price )  { m_price = price; }
  58     int GetPrice()              { return m_price; }
  59
  60 protected:
  61     int m_price;
  62 };
  63
  64 class MyCar
  65 {
  66 public:
  67     MyCar( int price ) : m_data( new MyCarRefData )
  68     {
  69         m_data->SetPrice( price );
  70     }
  71
  72     MyCar& operator =( const MyCar& tocopy )
  73     {
  74         m_data = tocopy.m_data;
  75         return *this;
  76     }
  77
  78     bool operator == ( const MyCar& other ) const
  79     {
  80         if (m_data.get() == other.m_data.get()) return true;
  81         return (m_data->GetPrice() == other.m_data->GetPrice());
  82     }
  83
  84     void SetPrice( int price )
  85     {
  86        UnShare();
  87        m_data->SetPrice( price );
  88     }
  89
  90     int GetPrice() const
  91     {
  92        return m_data->GetPrice();
  93     }
  94
  95     wxObjectDataPtr<MyCarRefData> m_data;
  96
  97 protected:
  98     void UnShare()
  99     {
 100         if (m_data->GetRefCount() == 1)
 101             return;
 102
 103         m_data.reset( new MyCarRefData( *m_data ) );
 104     }
 105 };
 106
 107 \end{verbatim}
 108
 109
 110 \latexignore{\rtfignore{\wxheading{Members}}}
 111
 112 \membersection{wxObjectDataPtr<T>::wxObjectDataPtr<T>}\label{wxobjectdataptrwxobjectdataptr}
 113
 114 \func{wxEXPLICIT}{wxObjectDataPtr<T>}{\param{T* }{ptr = NULL}}
 115
 116 Constructor. {\it ptr} is a pointer to the reference
 117 counted object to which this class points.
 118
 119 \func{}{wxObjectDataPtr<T>}{\param{const wxObjectDataPtr<T>\& }{tocopy}}
 120
 121 This copy constructor increases the count of the reference
 122 counted object to which {\it tocopy} points and then this
 123 class will point to, as well.
 124
 125 \membersection{wxObjectDataPtr<T>::\destruct{wxObjectDataPtr<T>}}\label{wxobjectdataptrdtor}
 126
 127 \func{}{\destruct{wxObjectDataPtr<T>}}{\void}
 128
 129 Calls \helpref{DecRef}{wxobjectrefdatadecref} on the reference
 130 counted object to which this class points.
 131
 132 \membersection{wxObjectDataPtr<T>::operator unspecified\_bool\_type}\label{wxobjectdataptroperatorbool}
 133
 134 \constfunc{}{operator unspecified\_bool\_type}{\void}
 135
 136 Conversion to a boolean expression (in a variant which is not
 137 convertable to anything but a boolean expression). If this class
 138 contains a valid pointer it will return {\it true}, if it contains
 139 a NULL pointer it will return {\it false}.
 140
 141 \membersection{wxObjectDataPtr<T>::operator*}\label{wxobjectdataptroperatorreft}
 142
 143 \constfunc{T \&}{operator*}{\void}
 144
 145 Returns a reference to the object. If the internal pointer is NULL
 146 this method will cause an assert in debug mode.
 147
 148 \membersection{wxObjectDataPtr<T>::operator->}\label{wxobjectdataptroperatorpointer}
 149
 150 \constfunc{T*}{operator->}{\void}
 151
 152 Returns a pointer to the reference counted object to which
 153 this class points. If this the internal pointer is NULL,
 154 this method will assert in debug mode.
 155
 156 \membersection{wxObjectDataPtr<T>::operator=}\label{wxobjectdataptroperatorassign}
 157
 158 \func{wxObjectDataPtr<T>\& operator}{operator=}{\param{const wxObjectDataPtr<T>\& }{tocopy}}
 159
 160 \func{wxObjectDataPtr<T>\& operator}{operator=}{\param{T* }{ptr}}
 161
 162 Assignment operators.
 163
 164 \membersection{wxObjectDataPtr<T>::get}\label{wxobjectdataptrget}
 165
 166 \constfunc{T*}{get}{\void}
 167
 168 Gets a pointer to the reference counted object to which
 169 this class points.
 170
 171 \membersection{wxObjectDataPtr<T>::reset}\label{wxobjectdataptrreset}
 172
 173 \func{void}{reset}{\param{T* }{ptr}}
 174
 175 Reset this class to {\it ptr} which points to a reference
 176 counted object.