如何将对象的内容复制到已经定义的对象中？

问：

我有一个名为的对象，它在我的主脚本中正在演变。我是这样定义的：GridGrid

class Grid{

public:
    std::vector <Polymer> PolymersInGrid;                 // all the polymers in the grid 
    std::vector <Particle> SolventInGrid;                 // solvent molecules in the grid 
    const int x;                                          // length of x-edge of grid 
    const int y;                                          // length of y-edge of grid 
    const int z;                                          // length of z-edge of grid 
    const double kT;                                      // energy factor 
    const double Emm ;                                    // monomer-monomer interaction 
    const double Ess ;                                    // solvent-solvent interaction 
    const double Ems_n ;                                  // monomer-solvent when Not aligned 
    const double Ems_a ;                                  // monomer-solvent when Aligned

    double Energy; 
    std::map <std::vector <int>, Particle> OccupancyMap;     // a map that gives the particle given the location
    

    Grid(int xlen, int ylen, int zlen, double kT_, double Emm_, double Ess_, double Ems_n_, double Ems_a_): x (xlen), y (ylen), z (zlen), kT (kT_), Emm(Emm_), Ess (Ess_), Ems_n (Ems_n_), Ems_a (Ems_a_) {        // Constructor of class
        // this->instantiateOccupancyMap(); 
    };


    // Destructor of class 
    ~Grid(){                                    

    }; 
...
};

在我的主脚本中，当我将运算符应用于 Grid 时，我的 Grid 会发生变化。

    Grid G = CreateGridObject(positions, topology);

    std::cout << "Energy of box is: " << G.Energy << std::endl;
    
    for (int i{0}; i<NumberOfMoves; i++){
        // perform evolution
        Grid G_test (BackwardReptation(G, 0)); 

        // check if G_test is a good structure
        if (G_test is good){ 
        // assign
        G = G_test; 
        }
    }

当我这样做时，我收到错误.object of type 'Grid' cannot be assigned because its copy assignment operator is implicitly deleted. copy assignment operator of 'Grid' is implicitly deleted because field 'x' is of const-qualified type 'const int'

我需要多次进化 Grid，检查它是否擅长每个进化步骤，并更改其内容。鉴于我希望保持网格的几何形状和能量表面 （），我该怎么做？Emm, Ess, Ems_n, Ems_aconst

编辑：对我的类对象的以下添加起作用了：

    Grid& operator=(const Grid& t){
        return *this; 
    } 

我知道&是一个重载运算符，可以用来指代变量的地址，可以用来表示右值、左值。我的问题是，如何阅读语法？Grid& 是什么意思？Grid& operator=