_type_traits

#ifndef MY_TYPE_TRAITS_H

#define MY_TYPE_TRAITS_H

 

struct my_true_type {

};

 

struct my_false_type {

};

 

template <class T>

struct my_type_traits

{

    typedef my_false_type has_trivial_destructor;

};

 

template<> struct my_type_traits<int>

{

    typedef my_true_type has_trivial_destructor;

};

 

#endif

 

#ifndef MY_DESTRUCT_H

#define MY_DESTRUCT_H

#include <iostream>

 

#include "my_type_traits.h"

 

using std::cout;

using std::endl;

 

template <class T1, class T2>

inline void myconstruct(T1 *p, const T2& value)

{

    new (p) T1(value);

}

 

template <class T>

inline void mydestroy(T *p)

{

    typedef typename my_type_traits<T>::has_trivial_destructor trivial_destructor;                   

    _mydestroy(p, trivial_destructor());                                                                       // 判断是否有trivial_destructor

}

 

template <class T>

inline void _mydestroy(T *p, my_true_type)

{

    cout << " do the trivial destructor " << endl;

}

 

template <class T>

inline void _mydestroy(T *p, my_false_type)

{

    cout << " do the real destructor " << endl;

    p->~T();

}

 

#endif

 

#include <iostream>

#include "my_destruct.h"

 

using std::cout;

using std::endl;

 

class TestClass

{

public:

    TestClass()

    {

        cout << "TestClass constructor call" << endl;

        data = new int(3);

    }

    TestClass(const TestClass& test_class)

    {

        cout << "TestClass copy constructor call. copy data:"

            << *(test_class.data) << endl;

        data = new int;

        *data = *(test_class.data) * 2;

    }

    ~TestClass()

    {

        cout << "TestClass destructor call. delete the data:" << *data << endl;

        delete data;

    }

private:

    int *data;

};

 

int main(void)

{

    {

        TestClass *test_class_buf;

        TestClass test_class;

 

        test_class_buf = (TestClass *)malloc(sizeof(TestClass));

        myconstruct(test_class_buf, test_class);

        mydestroy(test_class_buf);

        free(test_class_buf);

    }

 

    {

        int *int_p;

        int_p = new int;

        mydestroy(int_p);

        free(int_p);

    }

}