#include <iostream>
#include <memory>
#include <vector>
 
class IFoo
{
public:
	virtual void f() const noexcept = 0;
};
 
using IFooPtr = std::shared_ptr<IFoo>;
 
class Foo : public IFoo
{
public:
	void f() const noexcept override
	{
		std::cout << "Foo" << std::endl;
	}
};
 
class NaughtyFoo final : public Foo
{
public:
	void f() const noexcept override
	{
		std::cout << "This Foo is very naughty..." << std::endl;
	}
};
 
class GoodFoo final : public Foo
{};
 
int main()
{
	const auto naughtyFoo = std::make_shared<NaughtyFoo>();
	const auto goodFoo = std::make_shared<GoodFoo>();
 
	std::vector<IFooPtr> foos{ naughtyFoo, goodFoo };
	for (const auto& foo : foos)
	{
		if (foo)
		{
			foo->f();
		}
	}
 
	return 0;
}

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