Simple storage.

gistfile1.cpp

#include <iostream>
#include <vector>
#include <functional>
#include <initializer_list>

#define USE_EMPLACE     1
#define USE_UREF        1

using namespace std;

template <typename TT>
class Storage
{
public:
    Storage() {}
    
    Storage(Storage && x) {
        data=x.data;
        x.data=nullptr;
    }
    
    Storage(const Storage & x) {
        data = new TT(*(x.data));
    }
    
    Storage & operator = (const Storage & x) {
        if ( data ) delete data;
        data = new TT(*(x.data));
        return *this;
    }
    
    ~Storage() {
        if ( data ) delete data;
    }
    
#if USE_EMPLACE
    template <typename ...Params>
    void set(Params&&... params) {
        if ( data ) delete data;
        data = new TT(std::forward<Params>(params)...);
    }
#elif USE_UREF
    template <typename OTT>
    void set(OTT && value) {
        if ( data ) delete data;
        data = new TT(forward<OTT>(value));
    }
#else
    void set(const TT & value) {
        if ( data ) delete data;
        data = new TT(value);
    }
    
    void set(TT && value) {
        if ( data ) delete data;
        data = new TT(move(value));
    }
#endif
    
protected:
    TT * data = nullptr;
};

class Report
{
public:
    Report(int, float) : i_am_dead(false) { cout << "  Report(int,float);" << endl; }
    Report() : i_am_dead(false) { cout << "  Report();" << endl; }
    Report(const Report & ) : i_am_dead(false) { cout << "  Report(const Report&);" << endl; };
    Report(Report && h)  : i_am_dead(false) { cout << "  Report(&&);" << endl; h.i_am_dead = true; }
    Report & operator = (const Report&) { cout << "  Report::=(const Report&);" << endl; return *this; };
    ~Report() { cout << "  ~Report() i_am_dead=" << i_am_dead << endl; }
    bool i_am_dead;
};

Report f(int bla) {
    return Report();
}

int main(int argc, const char * argv[])
{
    cout << "set(Report());" << endl;
    {
        Storage<Report> xxx;
        xxx.set(Report());
    }
    /*
     set(Report());
         Report();
         Report(&&);
         ~Report() i_am_dead=1
         ~Report() i_am_dead=0
     */
    
    cout << "set(a);" << endl;
    {
        Storage<Report> xxx;
        Report a;
        xxx.set(a);
    }
    /*
     set(a);
        Report();
        Report(const Report&);
        ~Report() i_am_dead=0
        ~Report() i_am_dead=0
     */
    
    cout << "set(f(1));" << endl;
    {
        Storage<Report> xxx;
        xxx.set(f(1));
    }
    /*
     set(f(1));
        Report();
        Report(&&);
        ~Report() i_am_dead=1
        ~Report() i_am_dead=0
     */
    
#if USE_EMPLACE
    cout << "set(1,2.0f);" << endl;
    {
        Storage<Report> xxx;
        xxx.set(1,2.0f);
    }
    /*
     set(1,2.0f);
        Report(int,float);
        ~Report() i_am_dead=0
     */
#endif
    
    return 0;
}