以下是我的pro::surface
课程的(相关)代码:
/** Wraps up SDL_Surface* **/
class surface
{
SDL_Surface* _surf;
public:
/** Constructor.
** @param surf an SDL_Surface pointer.
**/
surface(SDL_Surface*);
/** Overloaded = operator. **/
void operator = (SDL_Surface*);
/** calls SDL_FreeSurface(). **/
void free();
/** destructor. Also free()s the internal SDL_Surface. **/
virtual ~surface();
}
现在的问题是,在我的main
函数中,对象会在实际渲染开始之前销毁自身(并因此调用危险的free()
SDL视频表面的析构函数!)。
int main(int argc, char** argv)
{
...
// declared here
pro::surface screen = SDL_SetVideoMode(320,240,16,SDL_HWSURFACE|SDL_DOUBLEBUF);
// event-handling done here, but the Video Surface is already freed!
while(!done) { ... } // note that "screen" is not used in this loop.
// hence, runtime error here. SDL_Quit() tries to free() the Video Surface again.
SDL_Quit();
return 0;
}
所以我的问题是,有没有办法阻止pro::surface
实例在程序结束前销毁自己?手动执行内存管理可以:
/* this works, since I control the destruction of the object */
pro::surface* screen = new pro::surface( SDL_SetVideoMode(..) );
/* it destroys itself only when **I** tell it to! Muhahaha! */
delete screen;
/* ^ but this solution uses pointer (ewww! I hate pointers) */
但是没有更好的方法,没有求助于指针?也许某种方式告诉堆栈不要删除我的对象呢?
答案 0 :(得分:9)
你违反了三法则,婊子。
pro::surface screen = SDL_SetVideoMode(320,240,16,SDL_HWSURFACE|SDL_DOUBLEBUF);
等于
pro::surface screen = pro::surface(SDL_SetVideoMode(320,240,16,SDL_HWSURFACE|SDL_DOUBLEBUF));
现在双倍自由,因为你违反了三条规则。因此,为您的类提供一个正确的复制构造函数/赋值运算符,或者禁止它们并正确地构造它。
编辑:这也解释了为什么你的指针版本工作正常 - 因为你没有调用副本。
答案 1 :(得分:2)
将屏幕包裹在一个特殊的包装中,将SDL_SetVideoMode
与SDL_Quit
配对,而不是SDL_FreeSurface
。
pro::screen screen(320, 240, 16, SDL_HWSURFACE | SDL_DOUBLEBUF);
// ...
修复你的副本ctor,显然是。