(苹果机)
我尝试了名称空间,包括警卫,编译指示一次等等。
基本上,这是结构:
的CMakeLists.txt
add_executable(Game Game/main.cpp Game/rtexture.cpp)
游戏/ main.cpp中
#include "cleanup.h"
//...
cleanup(foobar);
游戏/ rtexture.cpp
#include "cleanup.h"
//...
cleanup(foobar);
cleanup.h
//various includes
template<typename T, typename... Args>
void cleanup(T *t, Args&&... args){
//Cleanup the first item in the list
cleanup(t);
//Recurse to clean up the remaining arguments
cleanup(std::forward<Args>(args)...);
}
/*
* These specializations serve to free the passed argument and also provide the
* base cases for the recursive call above, eg. when args is only a single item
* one of the specializations below will be called by
* Cleanup(std::forward<Args>(args)...), ending the recursion
* We also make it safe to pass nullptrs to handle situations where we
* don't want to bother finding out which values failed to load (and thus are null)
* but rather just want to clean everything up and let cleanup sort it out
*/
template<>
void cleanup<SDL_Window>(SDL_Window *win){
if (!win){
return;
}
SDL_DestroyWindow(win);
}
template<>
void cleanup<SDL_Renderer>(SDL_Renderer *ren){
if (!ren){
return;
}
SDL_DestroyRenderer(ren);
}
template<>
void cleanup<SDL_Texture>(SDL_Texture *tex){
if (!tex){
return;
}
SDL_DestroyTexture(tex);
}
template<>
void cleanup<SDL_Surface>(SDL_Surface *surf){
if (!surf){
return;
}
SDL_FreeSurface(surf);
}
如果有人问,我确实接受了这个&#34; cleanup.h&#34;从一个教程,但无法找到一种方法将其包含在多个类中,而不会声明重复的符号。
Home at cruz45488-y19-MBA13-12 in ~/desktop/sdlworkspace/tmp
$ make
Linking CXX executable Game
duplicate symbol __ZN5RUtil7cleanupI10SDL_WindowJEEEvPT_DpOT0_ in:
CMakeFiles/Game.dir/Game/main.cpp.o
CMakeFiles/Game.dir/Game/rtexture.cpp.o
duplicate symbol __ZN5RUtil7cleanupI12SDL_RendererJEEEvPT_DpOT0_ in:
CMakeFiles/Game.dir/Game/main.cpp.o
CMakeFiles/Game.dir/Game/rtexture.cpp.o
duplicate symbol __ZN5RUtil7cleanupI11SDL_TextureJEEEvPT_DpOT0_ in:
CMakeFiles/Game.dir/Game/main.cpp.o
CMakeFiles/Game.dir/Game/rtexture.cpp.o
duplicate symbol __ZN5RUtil7cleanupI11SDL_SurfaceJEEEvPT_DpOT0_ in:
CMakeFiles/Game.dir/Game/main.cpp.o
CMakeFiles/Game.dir/Game/rtexture.cpp.o
有任何帮助吗?感谢。
答案 0 :(得分:10)
显式函数模板特化取决于一个定义规则,就像常规函数一样。添加inline
以允许标头中的定义;或者在源文件中定义它们,并在标题中包含声明。
答案 1 :(得分:6)
我没有看到任何包含警卫。此外,因为您将此标头包含在多个.cpp
文件中,#ifdef
不适用 - 您需要使用inline
关键字来告诉链接器,可以在多个文件中定义特定函数翻译单位。
#ifndef CLEANUP_H
#define CLEANUP_H
//includes...
template<>
inline void cleanup<SDL_Window>(SDL_Window *win){
if (!win){
return;
}
SDL_DestroyWindow(win);
}
template<>
inline void cleanup<SDL_Renderer>(SDL_Renderer *ren){
if (!ren){
return;
}
SDL_DestroyRenderer(ren);
}
template<>
inline void cleanup<SDL_Texture>(SDL_Texture *tex){
if (!tex){
return;
}
SDL_DestroyTexture(tex);
}
template<>
inline void cleanup<SDL_Surface>(SDL_Surface *surf){
if (!surf){
return;
}
SDL_FreeSurface(surf);
}
#endif /* CLEANUP_H */