simple smart ptr

smart.cc

#include <iostream>
using namespace std;

template<class T>
class Smart
{
private:
        struct Body
        {
                T *ptr;
                int count;
                Body(T* p) : ptr(p), count(1) {}
                ~Body() { delete ptr; }
        };
        Body * body;
public:
        Smart() : body(NULL) {}
        Smart(T *p) : body(new Body(p)) {}
        Smart(const Smart& smp) : body(smp.body)
        {
                if (body) ++(body->count);
        }

        Smart& operator= (const Smart& smp)
        {
                if (body != smp.body)
                {
                        if (body && --(body->count) == 0)
                        {
                                delete body;
                        }
                        body = smp.body;
                        if (body)
                        {
                                ++(body->count);
                        }
                }

                return *this;
        }

        ~Smart()
        {
                if (body && --(body->count) == 0)
                {
                        delete body;
                }
        }

        int refcount()
        {
                return body ? body->count : 0;
        }

        T* operator-> () const
        {
                return body->ptr;
        }

        T& operator* () const
        {
                return *(body->ptr);
        }

        operator T* () const
        {
                return body->ptr;
        }
};

struct Foo
{
        int bar;
        Foo() { cout << "const" << endl; }
        ~Foo() { cout << "dest" << endl; }
};

int main() {
        Smart<Foo> smp = new Foo();
        Smart<Foo> smp2 = smp;
        Smart<Foo> smp3;
        smp3 = smp2;
        cout << "ref count:" << smp.refcount() << endl;
        cout << "out of scope" << endl;
        return 0;
}