MakeSharedThisPointer.cpp

#include "pch.h"
#include <iostream>
#include <memory>
#include <unordered_set>

using namespace std;

template<typename Object>
void Deleter(Object* obj)
{
	delete obj;
};

class A : public std::enable_shared_from_this<A>
{
	friend int main(void);

	template<typename Object>
	friend void Deleter(Object* obj);

	static unordered_set<shared_ptr<A>> MapA;

public:
	std::shared_ptr<A> MakeShared( )
	{
		return shared_ptr<A>(this, Deleter<A>);
	}

	void InsertThis( )
	{
		MapA.insert(dynamic_pointer_cast<A>(this->shared_from_this( )));
	}

protected:
	A( )
	{
		cout << "Construct A" << endl;
	};

	virtual ~A( )
	{
		cout << "Destruct A" << endl;
	};

public:
	int memberA = 10;
};

unordered_set<shared_ptr<A>> A::MapA;

class B : public A
{
	friend int main(void);

	template<typename Object>
	friend void Deleter(Object* obj);

public:
	std::shared_ptr<B> MakeSharedB( )
	{
		return shared_ptr<B>(this, Deleter<B>);
	}

protected:
	B( )
	{
		cout << "Construct B" << endl;
	};

	~B( )
	{
		cout << "Destruct B" << endl;
	};

private:
	int memberB = -10;
};

int main( )
{
	A* newA = new A;
	shared_ptr<A> a = newA->MakeShared( );
	a->InsertThis( );

	B* newB = new B;
	shared_ptr<B> b = newB->MakeSharedB( );
	b->InsertThis( );

	return 0;
}