C / C++ / MFC

MyClassOld.h :
 
class CMyClassOld {
    //schema v1.0
  private:
    std::vector<CFoo> m_vecFooList;
    std::vector<CFoo2> m_vecFoo2List;
 
    //...
};

MyClass.h :
 
class CMyClass {
    //schema v2.0
  private:
    std::vector<CFoo> m_vecFooList;
    //m_vecFoo2List not existing anymore
 
    //...
};

#include "MyClassOld.h"
#include "MyClass.h"
 
CMyClassOld o1;
CMyClass o2;
 
//reads a CMyClassOld serialized object into o1
 
//converts it to a CMyClass object (into o2)
 
//Serializes o2

toxcct wrote:

what if the new business schema doesn't know its previous versions design ?

Ravi Bhavnani wrote:

since you can't do a silent upgrade (or a separate migration) without full knowledge of the old and new schemas

<br />
//// hello.h<br />
<br />
class One<br />
{<br />
public:<br />
   One(void);<br />
   ~One(void);<br />
public:<br />
   void oneFunction();<br />
   int oneX;<br />
<br />
};<br />
<br />
class Two<br />
{<br />
public:<br />
   Two(void);<br />
   ~Two(void);<br />
public:<br />
   static Two* m_ptrTwo; // <-- declare a static pointer to ourself {Two*)<br />
<br />
   void twoFunction();<br />
   int twoX;<br />
};<br />
<br />

<br />
//// hello.cpp<br />
<br />
#include "hello.h"<br />
<br />
<br />
Two*Two::m_ptrTwo = NULL;  // <-- define the static pointer for class Two here.. set it to NULL<br />
<br />
// constructor for class Two<br />
Two::Two(void)<br />
{<br />
   m_ptrTwo = this; // <-- setup the pointer to point to.... itself!!!<br />
}<br />
<br />

<br />
One::oneFunction()<br />
{<br />
   // Now here we will use the pointer from class Two to call anything in the public interface.<br />
   Two::m_ptrTwo->twoFunction();<br />
   Two::m_ptrTwo->twoX = 1234;<br />
}<br />
<br />