Create a smart pointer

[xgiovio]

Creare una classe unique_pointer per eliminare automaticamente i dati allocati dinamicamente senza chiamare la funzione delete.
Appena una istanza di unique_pointer viene rimossa dallo stack, il suo decostruttore eliminerà automaticamente anche i dati allocati nell'heap a cui punta.

L'overload degli operatori = e () permottono di effettuare assegnazioni dirette e perdere l'autorizzazione ad eliminare i dati se c'è un altro puntatore che punta agli stessi dati.

#include <iostream>
#include <iomanip>
#include <string>

using namespace std;


template <typename TIPO >class unique_pointer {
public:

    //////////////////////// constructor, initialize the pointer and ownership
    unique_pointer()
        :pointer(NULL),
        ownership(0)
    {}
    
    /////////////////////// the main utility of this class - delete the pointed data when it's removed from the stack
    ~unique_pointer(){
        if ( (pointer != NULL) && (ownership==1))
            delete pointer;
    }

    /////////////////// operator = defined to permit direct assignment
    void & operator= (TIPO * in_pointer){
    
        set_p(in_pointer);

    }

    //////////////////// operator () defined to pass the pointer to a general pointer and remove the permission to delete data
    operator() ( TIPO * new_pointer  ) {
        new_pointer = pointer;
        ownership = 0;
    }


private:

    void set_p ( TIPO * in_pointer){
        pointer = in_pointer;
        ownership = 1;
    }

    TIPO * pointer; // the pointer storage
    int ownership; // permission to delete data

};


int main () {
    
    unique_pointer <string > u_pointer; // create a smart pointer u_pointer;
    u_pointer = new string("ciao"); // new return address to u_pointer

    string* string_pointer;  // general pointer to a string class
    u_pointer(string_pointer); // u_pointer pass it's hidden pointer address to string_pointer


    cin.get(); //

return 0;

}