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

\section{wxScopedPtr}\label{wxscopedptr}

This is a simple scoped smart pointer implementation that is similar to 
the \urlref{Boost}{http://www.boost.org} smart pointers but rewritten to
use macros instead.

\wxheading{Example}

Below is an example of using a wxWindows scoped smart pointer and 
pointer array.

\begin{verbatim}
  class MyClass { /* ... */ };

  // declare a smart pointer to a MyClass called wxMyClassPtr
  wxDECLARE_SCOPED_PTR(MyClass, wxMyClassPtr)
  // declare a smart pointer to an array of chars
  wxDECLARE_SCOPED_ARRAY(char, wxCharArray)

  ...

  // define the first pointer class, must be complete
  wxDEFINE_SCOPED_PTR(MyClass, wxMyClassPtr)
  // define the second pointer class
  wxDEFINE_SCOPED_ARRAY(char, wxCharArray)

  // create an object with a new pointer to MyClass
  wxMyClassPtr theObj(new MyClass());
  // reset the pointer (deletes the previous one)
  theObj.reset(new MyClass());

  // access the pointer
  theObj->MyFunc();

  // create an object with a new array of chars
  wxCharArray theCharObj(new char[100]);

  // access the array
  theCharObj[0] = "!";
\end{verbatim}

\wxheading{Declaring new smart pointer types}

\begin{verbatim}
    wxDECLAR_SCOPED_PTR( TYPE,     // type of the values
                                CLASSNAME ); // name of the class
\end{verbatim}

A smart pointer holds a pointer to an object (which must be complete
when wxDEFINE\_SCOPED\_PTR() is called). The memory used by the object is
deleted when the smart pointer goes out of scope. The first argument
of the macro is the pointer type, the second is the name of the new
smart pointer class being created.  Below we will use wxScopedPtr to
represent the scoped pointer class, but the user may create the class with any
legal name.

\wxheading{Include files}

<wx/ptr\_scpd.h>

\wxheading{See also}

\helpref{wxScopedArray}{wxscopedarray}\rtfsp

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

\membersection{wxScopedPtr::wxScopedPtr}

\func{}{wxScopedPtr}{\param{type}{ * T = NULL}}

Creates the smart pointer with the given pointer or none if NULL.  On
compilers that support it, this uses the explicit keyword.

\membersection{wxScopedPtr::reset}

\func{\void}{reset}{\param{T}{ p * = NULL}}

Deletes the currently held pointer and sets it to 'p' or to NULL if no 
arguments are specified. This function does check to make sure that the
pointer you are assigning is not the same pointer that is already stored.

\membersection{wxScopedPtr::operator *}

\func{const T\&}{operator *}{\void}

This operator works like the standard C++ pointer operator to return the object
being pointed to by the pointer.  If the pointer is NULL or invalid this will
crash.

\membersection{wxScopedPtr::operator -\>}

\func{const T*}{operator -\>}{\void}

This operator works like the standard C++ pointer operator to return the pointer
in the smart pointer or NULL if it is empty.

\membersection{wxScopedPtr::get}

\func{const T*}{get}{\void}

This operator gets the pointer stored in the smart pointer or returns NULL if
there is none.

\membersection{wxScopedPtr::swap}

\func{\void}{swap}{\param{wxScopedPtr}{ \& ot}}

Swap the pointer inside the smart pointer with 'ot'. The pointer being swapped
must be of the same type (hence the same class name).