docs/doxygen/overviews/container.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        container.h
   3 // Purpose:     topic overview
   4 // Author:      wxWidgets team
   5 // RCS-ID:      $Id$
   6 // Licence:     wxWindows license
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9 /**
  10
  11 @page overview_container Container Classes
  12
  13 Classes: wxList<T>, wxArray<T>, wxVector<T>
  14
  15 wxWidgets uses itself several container classes including doubly-linked lists
  16 and dynamic arrays (i.e. arrays which expand automatically when they become
  17 full). For both historical and portability reasons wxWidgets does not use STL
  18 which provides the standard implementation of many container classes in C++.
  19
  20 First of all, wxWidgets has existed since well before STL was written, and
  21 secondly we don't believe that today compilers can deal really well with all of
  22 STL classes (this is especially true for some less common platforms). Of
  23 course, the compilers are evolving quite rapidly and hopefully their progress
  24 will allow to base future versions of wxWidgets on STL - but this is not yet
  25 the case.
  26
  27 wxWidgets container classes don't pretend to be as powerful or full as STL
  28 ones, but they are quite useful and may be compiled with absolutely any C++
  29 compiler. They're used internally by wxWidgets, but may, of course, be used in
  30 your programs as well if you wish.
  31
  32 The list classes in wxWidgets are doubly-linked lists which may either own the
  33 objects they contain (meaning that the list deletes the object when it is
  34 removed from the list or the list itself is destroyed) or just store the
  35 pointers depending on whether or not you called wxList<T>::DeleteContents()
  36 method.
  37
  38 Dynamic arrays resemble C arrays but with two important differences: they
  39 provide run-time range checking in debug builds and they automatically expand
  40 the allocated memory when there is no more space for new items. They come in
  41 two sorts: the "plain" arrays which store either built-in types such as "char",
  42 "int" or "bool" or the pointers to arbitrary objects, or "object arrays" which
  43 own the object pointers to which they store.
  44
  45 For the same portability reasons, the container classes implementation in
  46 wxWidgets does not use templates, but is rather based on C preprocessor i.e. is
  47 done with the macros: WX_DECLARE_LIST() and WX_DEFINE_LIST() for the linked
  48 lists and WX_DECLARE_ARRAY(), WX_DECLARE_OBJARRAY() and WX_DEFINE_OBJARRAY()
  49 for the dynamic arrays.
  50
  51 The "DECLARE" macro declares a new container class containing the elements of
  52 given type and is needed for all three types of container classes: lists,
  53 arrays and objarrays. The "DEFINE" classes must be inserted in your program in
  54 a place where the @e full declaration of container element class is in scope
  55 (i.e. not just forward declaration), otherwise destructors of the container
  56 elements will not be called!
  57
  58 As array classes never delete the items they contain anyhow, there is no
  59 WX_DEFINE_ARRAY() macro for them.
  60
  61 Examples of usage of these macros may be found in wxList<T> and wxArray<T>
  62 documentation.
  63
  64 Finally, wxWidgets predefines several commonly used container classes. wxList
  65 is defined for compatibility with previous versions as a list containing
  66 wxObjects and wxStringList as a list of C-style strings (char *), both of these
  67 classes are deprecated and should not be used in new programs. The following
  68 array classes are defined: wxArrayInt, wxArrayLong, wxArrayPtrVoid and
  69 wxArrayString. The first three store elements of corresponding types, but
  70 wxArrayString is somewhat special: it is an optimized version of wxArray which
  71 uses its knowledge about wxString reference counting schema.
  72
  73 */
  74