include/wx/html/forcelink.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        forcelink.h
   3 // Purpose:     see bellow
   4 // Author:      Vaclav Slavik
   5 // Copyright:   (c) 1999 Vaclav Slavik
   6 // Licence:     wxWindows Licence
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9 /*
  10
  11 DESCRPITON:
  12
  13 mod_*.cpp files contain handlers for tags. These files are modules - they contain
  14 one wxTagModule class and it's OnInit() method is called from wxApp's init method.
  15 The module is called even if you only link it into the executable, so everything
  16 seems wonderful.
  17
  18 The problem is that we have these modules in LIBRARY and mod_*.cpp files contain
  19 no method nor class which is known out of the module. So the linker won't
  20 link these .o/.obj files into executable because it detected that it is not used
  21 by the program.
  22
  23 To workaround this I introduced set of macros FORCE_LINK_ME and FORCE_LINK. These
  24 macros are generic and are not limited to mod_*.cpp files. You may find them quite
  25 useful somewhere else...
  26
  27 How to use them:
  28 let's suppose you want to always link file foo.cpp and that you have module
  29 always.cpp that is certainly always linked (e.g. the one with main() function
  30 or htmlwin.cpp in wxHtml library).
  31
  32 Place FORCE_LINK_ME(foo) somewhere in foo.cpp and FORCE_LINK(foo) somewhere
  33 in always.cpp
  34 See mod_*.cpp and htmlwin.cpp for example :-)
  35
  36 */
  37
  38
  39 #ifndef __FORCELINK_H__
  40 #define __FORCELINK_H__
  41
  42
  43
  44 // This must be part of the module you want to force:
  45 #define FORCE_LINK_ME(module_name)                                    \
  46                 int _link_dummy_func_##module_name ()                 \
  47                 {                                                     \
  48                     return 1;                                         \
  49                 }
  50
  51
  52 // And this must be somewhere where it certainly will be linked:
  53 #define FORCE_LINK(module_name)                                       \
  54                 extern int _link_dummy_func_##module_name ();         \
  55                 static int _link_dummy_var_##module_name =            \
  56                                _link_dummy_func_##module_name ();
  57
  58
  59 #endif // __FORCELINK_H__