#include <iostream>
using namespace std;
 
class interface_d
{
public:
	virtual ~interface_d() {}
};
 
class d1
	: public interface_d
{
public:
	d1() : interface_d(), m_x(new int) {}
	virtual ~d1()
	{
		delete m_x;
	}
 
private:
	int *m_x;
};
 
class base
{
public:
	base(interface_d *impl) : m_impl(impl) {}
	virtual ~base()
	{
		// ... do something before clear impl
		delete m_impl;
		// ... do something after clear impl
	}
 
private:
	interface_d *m_impl;
};
 
int main() {
	base x(new d1);
	return 0;
}

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