c++ - 转换运算符重载以返回 2-dim 数组以访问外部库

Question

class M33
{
public:
    double m[3][3];

    double (*GetM())[3] {
        return m;
    }
};

// call to JPL cspice f2c generated routine
// void mxm_c ( const double   m1  [3][3],
//              const double   m2  [3][3],
//              double         mout[3][3] )

void test()
{
    M33 m1;
    M33 m2;
    M33 mOut;
    mxm_c( m1.m, m2.m, mOut.m ); // this works
    mxm_c( m1.GetM(), m2.GetM(), mOut.GetM() ); // this works
}

使用 VS2013。问题:是否可以使用诸如...之类的转换运算符

operator double*[3] () // this does not compile
{
    return m;
}

从而允许这种编码风格的快捷方式？

mxm_c( m1, m2, mOut ); // this does not work

Answer 1

是的，你可以做这样的运算符。当涉及复杂类型时，最好引入别名:

using Ptr = double (*)[3];

operator Ptr()
{
    return GetM();
}

[Live example]