设计一个类，只能在栈/堆上创建对象

class HeapOnly {
public:
    static HeapOnly* CreateObject() {
        return new HeapOnly;
    }
private:
    // 将构造函数私有化
    HeapOnly() {}
    // 防拷贝
    HeapOnly(const HeapOnly&);
    // 防拷贝C++11写法
    // HeapOnly(const HeapOnly&) = delete;
};

class  HeapOnly {
public:
    HeapOnly() {}
    void  Destory() { delete this; }
private:
    // 如果类的析构函数是私有的，则编译器不会在栈空间上为类对象分配内存
    ~HeapOnly() {}
};

class StackOnly {
public:
    static StackOnly CreateObject() {
        return StackOnly();
    }
private:
    StackOnly() {}
};

class StackOnly {
public:
    StackOnly() {}
private:
    void* operator new(size_t size);
    void operator delete(void* p);
};