Use PImpl with custom stream: is my solution optimal?

[LB]

http://ideone.com/RKf3uC

#include <iostream>
#include <string>
#include <memory>

struct Other
{
	virtual void print() = 0;
	virtual ~Other() = default;
};

struct Base
{
	Base(Other *o)
	{
		o->print();
	}
	virtual ~Base() = default;
};
struct Derived : Base
{
	Derived();
	virtual ~Derived();
private:
	struct My;
	std::unique_ptr<My> my;
};

int main()
{
	Derived d;
}

struct Derived::My : Other
{
	std::string s = "It works";
	virtual void print()
	{
		std::cout << s << std::endl;
	}
};
Derived::Derived()
: my(new My)
, Base(my.get())
{
}
Derived::~Derived() = default;

Base is std::basic_*stream, Other is std::basic_streambuf. The code generates a runtime error, as I was afraid it would, because the base has to be initialized before any members of the derived class.

Here is my solution: http://ideone.com/tSVEgp

struct Derived : Base
{
	Derived();
	virtual ~Derived();
private:
	struct My;
	std::unique_ptr<My> my;
	My *temp; //
};

//...

Derived::Derived()
: Base(temp = new My) //
, my(temp)            //
{
	temp = nullptr; //
}

This works, but would there still be any issue with this? Is there a better way? I cannot define My inline in the header. Should I just abandon the uniue_ptr altogether?

[LB]

If I were to just forget about the unique_ptr altogether, would it be better or worse to use a raw pointer?

[o1vk4iN6]

If you want to avoid the temp pointer in the class you could do something like this, tho it's not without it's limitations.

http://ideone.com/rJ9bKh

[LB]

That's clever, though what imitations are you referring to?

[o1vk4iN6]

Well if you don't want to reveal the pointer you'd need 2 constructors for each. One private with the pointer and another public without it. I guess it isn't that big of a deal since the public ones are basically one liners.

[LB]

That's not a limitation, that's a drawback. For a second I thought this was limited in some way, but it really isn't - it just has that drawback.