docs/doxygen/overviews/container.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        container
   3 // Purpose:     topic overview
   4 // Author:      wxWidgets team
   5 // RCS-ID:      $Id$
   6 // Licence:     wxWindows license
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9 /*!
  10
  11  @page container_overview Container classes overview
  12
  13  Classes: #wxListT, #wxArrayT, #wxVectorT
  14  wxWidgets uses itself several container classes including doubly-linked lists
  15  and dynamic arrays (i.e. arrays which expand automatically when they become
  16  full). For both historical and portability reasons wxWidgets does not
  17  use STL which provides the standard implementation of many container classes in
  18  C++. First of all, wxWidgets has existed since well before STL was written, and
  19  secondly we don't believe that today compilers can deal really well with all of
  20  STL classes (this is especially @true for some less common platforms). Of
  21  course, the compilers are evolving quite rapidly and hopefully their progress
  22  will allow to base future versions of wxWidgets on STL - but this is not yet
  23  the case.
  24  wxWidgets container classes don't pretend to be as powerful or full as STL
  25  ones, but they are quite useful and may be compiled with absolutely any C++
  26  compiler. They're used internally by wxWidgets, but may, of course, be used in
  27  your programs as well if you wish.
  28  The list classes in wxWidgets are doubly-linked lists which may either own the
  29  objects they contain (meaning that the list deletes the object when it is
  30  removed from the list or the list itself is destroyed) or just store the
  31  pointers depending on whether you called or not
  32  wxList::DeleteContents method.
  33  Dynamic arrays resemble C arrays but with two important differences: they
  34  provide run-time range checking in debug builds and they automatically expand
  35  the allocated memory when there is no more space for new items. They come in
  36  two sorts: the "plain" arrays which store either built-in types such as "char",
  37  "int" or "bool" or the pointers to arbitrary objects, or "object arrays" which
  38  own the object pointers to which they store.
  39  For the same portability reasons, the container classes implementation in wxWidgets
  40  does not use templates, but is rather based on C preprocessor i.e. is done with
  41  the macros: @e WX_DECLARE_LIST and @e WX_DEFINE_LIST for the linked
  42  lists and @e WX_DECLARE_ARRAY, @e WX_DECLARE_OBJARRAY and @e WX_DEFINE_OBJARRAY for
  43  the dynamic arrays. The "DECLARE" macro declares a
  44  new container class containing the elements of given type and is needed for all
  45  three types of container classes: lists, arrays and objarrays. The "DEFINE"
  46  classes must be inserted in your program in a place where the @b full
  47  declaration of container element class is in scope (i.e. not just forward
  48  declaration), otherwise destructors of the container elements will not be
  49  called! As array classes never delete the items they contain anyhow, there is
  50  no WX_DEFINE_ARRAY macro for them.
  51  Examples of usage of these macros may be found in #wxList and
  52  #wxArray documentation.
  53  Finally, wxWidgets predefines several commonly used container classes. wxList
  54  is defined for compatibility with previous versions as a list containing
  55  wxObjects and wxStringList as a list of C-style strings (char *), both of these
  56  classes are deprecated and should not be used in new programs. The following
  57  array classes are defined: wxArrayInt, wxArrayLong, wxArrayPtrVoid and
  58  wxArrayString. The first three store elements of corresponding types, but
  59  wxArrayString is somewhat special: it is an optimized version of wxArray which
  60  uses its knowledge about #wxString reference counting
  61  schema.
  62
  63  */
  64
  65