Modify const parameter reference - c++

Question

Ok so I have two classes that look like:
class Item
{
private:
HANDLE Parent;
public:
Item(const Item &I) = delete;
Item(Item &&I) = delete;
void SetParent(HANDLE Handle);
Item& operator = (const Item &I) = delete;
Item& operator = (Item &&I);
};
void Item::SetParent(HANDLE Handle)
{
this->Parent = Handle;
}
Item& Item::operator = (Item&& I) {/*Do Move Here*/}
class Box
{
private:
HANDLE Handle;
public:
void Add(const Item &I);
};
void Box::Add(const Item &I)
{
I.SetParent(this->Handle); //Error.. Item I is const.
}
I get the error that I is const and that makes sense but I need a way to SetParent of Item I without losing the ability to construct I in place as so:
Box B(Item());
instead of:
Item I;
Box B(I);
Any ideas how I can keep inline construction of I while being able to modify it by calling SetParent?

Answer 1

A solution is to declare the Parent member as mutable and to make the SetParent method constant. A sample code is following and available online
typedef int HANDLE;
class Item
{
private:
mutable HANDLE Parent;
public:
Item(const Item &I) = delete;
Item(Item &&I) = delete;
void SetParent(HANDLE Handle) const;
Item& operator = (const Item &I) = delete;
Item& operator = (Item &&I);
};
void Item::SetParent(HANDLE Handle) const
{
this->Parent = Handle;
}
class Box
{
private:
HANDLE Handle;
public:
void Add(const Item &I);
public:
Box(const Item &I) {
Add(I);
}
};
void Box::Add(const Item &I)
{
I.SetParent(this->Handle); //Error.. Item I is const.
}
int main(void) {
return 0;
}