I'm working in Visual Studio 2010, using C++ code. What I'm trying to do is change the value of a preprocessor directive during run time, not sure if it's possible but i've tried this..

somefile.h

static int mValue = 0;
#define POO = mValue;
...

#if POO 0
//define class methods
#else
//define class methods differently
}

main.cpp

main()
{

//Code calls constructor and methods allowed when POO is 0

//Code increments mValue

//Code calls constructor and methods allowed when POO is 1


}

How can POO be changed so that class objects uses a different implementation of other methods? Or if it's not possible, what's a another approach to this?