docs/latex/wx/scpdptr.tex

   1 \section{\class{wxScopedPtr}}\label{wxscopedptr}
   2
   3 This is a simple scoped smart pointer implementation that is similar to
   4 the \urlref{Boost}{http://www.boost.org/} smart pointers but rewritten to
   5 use macros instead.
   6
   7 A smart pointer holds a pointer to an object. The memory used by the object is
   8 deleted when the smart pointer goes out of scope. This class is different from
   9 the \texttt{std::auto\_ptr<>} in so far as it doesn't provide copy constructor
  10 nor assignment operator. This limits what you can do with it but is much less
  11 surprizing than the ``destructive copy'' behaviour of the standard class.
  12
  13 \wxheading{Example}
  14
  15 Below is an example of using a wxWindows scoped smart pointer and
  16 pointer array.
  17
  18 \begin{verbatim}
  19   class MyClass { /* ... */ };
  20
  21   // declare a smart pointer to a MyClass called wxMyClassPtr
  22   wxDECLARE_SCOPED_PTR(MyClass, wxMyClassPtr)
  23   // declare a smart pointer to an array of chars
  24   wxDECLARE_SCOPED_ARRAY(char, wxCharArray)
  25
  26   ...
  27
  28   // define the first pointer class, must be complete
  29   wxDEFINE_SCOPED_PTR(MyClass, wxMyClassPtr)
  30   // define the second pointer class
  31   wxDEFINE_SCOPED_ARRAY(char, wxCharArray)
  32
  33   // create an object with a new pointer to MyClass
  34   wxMyClassPtr theObj(new MyClass());
  35   // reset the pointer (deletes the previous one)
  36   theObj.reset(new MyClass());
  37
  38   // access the pointer
  39   theObj->MyFunc();
  40
  41   // create an object with a new array of chars
  42   wxCharArray theCharObj(new char[100]);
  43
  44   // access the array
  45   theCharObj[0] = "!";
  46 \end{verbatim}
  47
  48 \wxheading{Declaring new smart pointer types}
  49
  50 To declare the smart pointer class \texttt{CLASSNAME} containing pointes to a
  51 (possibly incomplete) type \texttt{TYPE} you should use
  52 \begin{verbatim}
  53     wxDECLARE_SCOPED_PTR( TYPE,     // type of the values
  54                                 CLASSNAME ); // name of the class
  55 \end{verbatim}
  56
  57 And later, when \texttt{TYPE} is fully defined, you must also use
  58 \begin{verbatim}
  59     wxDEFINE_SCOPED_PTR( TYPE, CLASSNAME );
  60 \end{verbatim}
  61 to implement the scoped pointer class.
  62
  63 The first argument of these macro is the pointer type, the second is the name
  64 of the new smart pointer class being created.  Below we will use wxScopedPtr to
  65 represent the scoped pointer class, but the user may create the class with any
  66 legal name.
  67
  68 Alternatively, if you don't have to separate the point of declaration and
  69 definition of this class and if you accept the standard naming convention, that
  70 is that the scoped pointer for the class \texttt{Foo} is called
  71 \texttt{FooPtr}, you can use a single macro which replaces two macros above:
  72 \begin{verbatim}
  73     wxDEFINE_SCOPED_PTR_TYPE( TYPE );
  74 \end{verbatim}
  75 Once again, in this cass \texttt{CLASSNAME} will be \texttt{TYPEPtr}.
  76
  77 \wxheading{Include files}
  78
  79 <wx/ptr\_scpd.h>
  80
  81 \wxheading{See also}
  82
  83 \helpref{wxScopedArray}{wxscopedarray}\rtfsp
  84
  85 \latexignore{\rtfignore{\wxheading{Members}}}
  86
  87 \membersection{wxScopedPtr::wxScopedPtr}
  88
  89 \func{}{wxScopedPtr}{\param{type}{ * T = NULL}}
  90
  91 Creates the smart pointer with the given pointer or none if NULL.  On
  92 compilers that support it, this uses the explicit keyword.
  93
  94 \membersection{wxScopedPtr::release}
  95
  96 \func{T *}{release}{\void}
  97
  98 Returns the currently hold pointer and resets the smart pointer object to
  99 {\tt NULL}. After a call to this function the caller is responsible for
 100 deleting the pointer.
 101
 102
 103 \membersection{wxScopedPtr::reset}
 104
 105 \func{\void}{reset}{\param{T}{ p * = NULL}}
 106
 107 Deletes the currently held pointer and sets it to {\it p} or to NULL if no
 108 arguments are specified. This function does check to make sure that the
 109 pointer you are assigning is not the same pointer that is already stored.
 110
 111 \membersection{wxScopedPtr::operator *}
 112
 113 \func{const T\&}{operator *}{\void}
 114
 115 This operator works like the standard C++ pointer operator to return the object
 116 being pointed to by the pointer.  If the pointer is NULL or invalid this will
 117 crash.
 118
 119 \membersection{wxScopedPtr::operator -$>$} % TODO
 120
 121 \func{const T*}{operator -$>$}{\void} % TODO
 122
 123 This operator works like the standard C++ pointer operator to return the pointer
 124 in the smart pointer or NULL if it is empty.
 125
 126 \membersection{wxScopedPtr::get}
 127
 128 \func{const T*}{get}{\void}
 129
 130 This operator gets the pointer stored in the smart pointer or returns NULL if
 131 there is none.
 132
 133 \membersection{wxScopedPtr::swap}
 134
 135 \func{\void}{swap}{\param{wxScopedPtr}{ \& other}}
 136
 137 Swap the pointer inside the smart pointer with {\it other}. The pointer being
 138 swapped must be of the same type (hence the same class name).
 139