also in etwa so:

template<class Bar1,class Bar2>
class Foo
{
    private:
        Bar1 bar1;
        Bar2 bar2;
    public:
        void test()
        {
             if(!bar1.doSth())
                  bar2.fubar();
        }
};

class Example1
{
    public:
        bool doSth()
        {
             return true;
        }
};
class Example2
{
    public:
        void fubar()
        {
             ...
        }
};

...
Foo<Example1,Example2> test;