d54cf7ff13
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@52014 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
72 lines
3.6 KiB
C
72 lines
3.6 KiB
C
/////////////////////////////////////////////////////////////////////////////
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// Name: container.h
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// Purpose: topic overview
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// Author: wxWidgets team
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// RCS-ID: $Id$
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// Licence: wxWindows license
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/////////////////////////////////////////////////////////////////////////////
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/*!
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@page overview_container Container classes overview
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Classes: #wxListT, #wxArrayT, #wxVectorT
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wxWidgets uses itself several container classes including doubly-linked lists
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and dynamic arrays (i.e. arrays which expand automatically when they become
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full). For both historical and portability reasons wxWidgets does not use STL
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which provides the standard implementation of many container classes in C++.
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First of all, wxWidgets has existed since well before STL was written, and
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secondly we don't believe that today compilers can deal really well with all of
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STL classes (this is especially true for some less common platforms). Of
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course, the compilers are evolving quite rapidly and hopefully their progress
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will allow to base future versions of wxWidgets on STL - but this is not yet
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the case.
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wxWidgets container classes don't pretend to be as powerful or full as STL
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ones, but they are quite useful and may be compiled with absolutely any C++
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compiler. They're used internally by wxWidgets, but may, of course, be used in
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your programs as well if you wish.
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The list classes in wxWidgets are doubly-linked lists which may either own the
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objects they contain (meaning that the list deletes the object when it is
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removed from the list or the list itself is destroyed) or just store the
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pointers depending on whether you called or not wxList::DeleteContents method.
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Dynamic arrays resemble C arrays but with two important differences: they
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provide run-time range checking in debug builds and they automatically expand
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the allocated memory when there is no more space for new items. They come in
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two sorts: the "plain" arrays which store either built-in types such as "char",
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"int" or "bool" or the pointers to arbitrary objects, or "object arrays" which
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own the object pointers to which they store.
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For the same portability reasons, the container classes implementation in wxWidgets
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does not use templates, but is rather based on C preprocessor i.e. is done with
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the macros: @e WX_DECLARE_LIST and @e WX_DEFINE_LIST for the linked
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lists and @e WX_DECLARE_ARRAY, @e WX_DECLARE_OBJARRAY and @e WX_DEFINE_OBJARRAY for
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the dynamic arrays.
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The "DECLARE" macro declares a new container class containing the elements of
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given type and is needed for all three types of container classes: lists,
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arrays and objarrays. The "DEFINE" classes must be inserted in your program
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in a place where the @b full declaration of container element class is in scope
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(i.e. not just forward declaration), otherwise destructors of the container
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elements will not be called!
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As array classes never delete the items they contain anyhow, there is
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no WX_DEFINE_ARRAY macro for them.
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Examples of usage of these macros may be found in #wxList and #wxArray documentation.
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Finally, wxWidgets predefines several commonly used container classes. wxList
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is defined for compatibility with previous versions as a list containing
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wxObjects and wxStringList as a list of C-style strings (char *), both of these
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classes are deprecated and should not be used in new programs. The following
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array classes are defined: wxArrayInt, wxArrayLong, wxArrayPtrVoid and
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wxArrayString. The first three store elements of corresponding types, but
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wxArrayString is somewhat special: it is an optimized version of wxArray which
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uses its knowledge about #wxString reference counting schema.
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*/
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