C++ High Performance

A common pitfall - moving non-resources

There is one common pitfall when using default created move-assignments: classes which mix simple types with more advanced types. As opposed to more advanced types, simple types such as integers, Booleans, and such are simply copied when moved as they don't handle any resources.

When a simple type is mixed with a resource-owning type, the move-assignment becomes a mixture of move and copy.

Here is an example of a class which will fail:

class TowerList { public:   TowerList() : max_height_idx_{1}, tower_heights_{25.0f, 44.0f, 12.0f} {}  auto get_max_tower_height() const {     return max_height_idx_ >= 0 ?       tower_heights_[max_height_idx_] : 0.0f;   }   std::vector<float> tower_heights_{};  int max_height_idx_{-1}; ...