这个错误:
error C2678: binary '=' : no operator found which takes a left-hand operand of type 'const std::string' (or there is no acceptable conversion) c:\program files (x86)\microsoft visual studio 10.0\vc\include\utility 216
发生在此函数的唯一行上:
void Animation::AddAnimation(std::string name, AnimationFrameSet& animation) {
_animations.insert(std::make_pair(name, animation));
}
_animations
是一个std::map<std::string, AnimationFrameSet>
AnimationFrameSet 声明了一个 operator=(...) 和一个复制构造函数,但奇怪的是,编译器说它在尝试复制const std::string
... 时失败,即使字符串甚至没有作为const
.
我一生都无法弄清楚(甚至不记得!:P)为什么这是/应该抛出/抛出错误。
谢谢。
编辑
我有点困惑为什么这不起作用的原因是不同的类使用非常相似的实现并且它不会引发错误:
BITMAP* BitmapCache::GetBitmap(std::string filename) {
//Return NULL if a bad filename was passed.
if(filename.empty()) return NULL;
if(exists(filename.c_str()) == false) return NULL;
//Reduce incorrect results by forcing slash equality.
filename = fix_filename_slashes(&filename[0]);
//Clean the cache if it's dirty.
CleanCache();
//Search for requested BITMAP.
MapStrBmpIter _iter = _cache.find(filename);
//If found, return it.
if(_iter != _cache.end()) return _iter->second;
//Otherwise, create it, store it, then return it.
BITMAP* result = load_bmp(filename.c_str(), NULL);
if(result == NULL) return NULL;
/*Similar insert line, a non-const std::string that was passed in is passed to a std::make_pair(...) function*/
_cache.insert(std::make_pair(filename, result));
return result;
}
类型定义:
typedef std::map<std::string, BITMAP*> MapStrBmp;
typedef MapStrBmp::iterator MapStrBmpIter;