shared_ptr tip

1. prohibit delete raw pointer( use protected destructor )

class A

{

public:

virtual void sing() = 0;

protected:

virtual ~A() {}

};

class B : public A

{

public:

virtual void sing()

{

std::cout <<"Do re mi fa so la";

}

};

boost::shared_ptr<A> createA()

{

boost::shared_ptr<A> p ( new B() );

return p;

}

int main()

{

boost::shared_ptr<A> test = createA()

delete test.get();  // compile error  because ~A is protected

}

2. prohibit delete raw pointer( nest class)

class A

{

class deleter

{

public:

void operator() (A * p )

{

delete P;

}

};

friend class deleter;

public:

virtual void sing()

{

std::cout << "Lalalalalalalala";

}

static boost::shared_ptr<A> createA()

{

boost::shared_ptr<A> p(new A(), A::deleter() );

return p;

}

protected:

virtual ~A() {}

};