RAII value

raii_value.cpp

#include <iostream>
#include <type_traits>


template<typename T, class Deleter>
class raii_value
{
public:
    static_assert(std::is_fundamental<T>::value, "raii_value must hold a fundamental type");
    
    // Must be initialized
    raii_value() = delete;
    
    raii_value(const T value)
    : m_value(value)
    {}
    
    ~raii_value()
    {
        Deleter d;
        // Enforce passing reference
        T& value_ref = m_value;
        d(value_ref);
    }
    
    // Implicit cast to type T
    operator T&() { return m_value; }
    
    raii_value<T, Deleter>& operator=(const T value)
    {
        m_value = value;
        return *this;
    }
    
private:
    T m_value;
};

struct Delete_int
{
    void operator()(int& value)
    {
        std::cout << "deleter run" << std::endl;
        value = 0;
        std::cout << "deleter done" << std::endl;
    }
};


int main() {
    raii_value<int, Delete_int> a{5};
    std::cout << a << std::endl;
    a = 6;
    std::cout << a << std::endl;
}