[英]C++ Friend constructor
我有兩個類: Point
,它只存在於Space
class Point
{
private:
Point(const Space &space, int x=0, int y=0, int z=0);
int x, y, z;
const Space & m_space;
};
構造函數是故意私有的,我不希望它被直接調用。 我想用這種方式創建點數
Space mySpace;
Point myPoint = mySpace.Point(5,7,3);
有沒有辦法這樣做? 謝謝。
是的,將Space::Point()
聲明為友元方法。 該方法將獲得Point
的私人成員的訪問權限。
class Point
{
public:
friend Point Space::Point(int, int, int);
private:
// ...
我會這樣做:
class Space
{
public:
class Point
{
private:
Point(const Space &space, int x=0, int y=0, int z=0);
int m_x, m_y, m_z;
const Space & m_space;
friend class Space;
};
Point MakePoint(int x=0, int y=0, int z=0);
};
Space::Point::Point(const Space &space, int x, int y, int z)
: m_space(space), m_x(x), m_y(y), m_z(z)
{
}
Space::Point Space::MakePoint(int x, int y, int z)
{
return Point(*this, x, y, z);
}
Space mySpace;
Space::Point myPoint = mySpace.MakePoint(5,7,3);
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