c++ 类对象初始化

Question

最近在看ros代码，第一次见到这样的类对象初始化。
结构大概是这样的，MapCell 与MapGrid两个类没有继承关系。trajetory_planner中MapCell对象的初始化是怎么进行的？

trajetory_planner.h

class TrajectoryPlanner{
    friend class TrajectoryPlannerTest;
    public:
    ...
    private:
    ...
        MapGrid path_map_;
}

trajetory_planner.cpp

...
MapCell cell = path_map_(cx, cy);//这里是怎么初始化的
if (cell.within_robot) {
        return false;
    }
...

map_grid.h

class MapGrid{
public:
    MapGrid();
    MapGrid(unsigned int size_x, unsigned int size_y);
    ...
    inline MapCell& operator() (unsigned int x, unsigned int y){
        return map_[size_x_ * y + x];
    }
    inline MapCell operator() (unsigned int x, unsigned int y) const {
        return map_[size_x_ * y + x];
    }
private:
      std::vector<MapCell> map_;
}

map_cell.h

class MapCell{
public:
    MapCell();
    MapCell(const MapCell& mc);
    unsigned int cx, cy; 
    double target_dist; 
    bool target_mark;
    bool within_robot;
}

map_cell.cpp

MapCell::MapCell()
    : cx(0), cy(0),
      target_dist(DBL_MAX),
      target_mark(false),
      within_robot(false)
  {}
MapCell::MapCell(const MapCell& mc)
    : cx(mc.cx), cy(mc.cy),
      target_dist(mc.target_dist),
      target_mark(mc.target_mark),
      within_robot(mc.within_robot)
  {}

Answer 1

就是调用MapCell的operator()获取到一个MapGrid然后进行拷贝初始化。