gistfile1.txt

#include <stdlib.h>

#ifdef WIN32
#define DLLEXPORT __declspec(dllexport)
#else
#define DLLEXPORT extern
#endif

class Foo {
public:
    Foo();
    ~Foo();
    virtual int TakeAnInt(int i) {
        return 1;
    }
};

Foo::Foo() {};
Foo::~Foo() {};

should be this I guess:

class Foo {
public:
    Foo();
    ~Foo();
    virtual int TakeAnInt(int i) {
        return 1;
    }
};