How can I write this interfaces correctly?
You can always forward declare classes and use pointers or references in the code that sees the forward declaration.
As soon any code needs to refer class members, the full class declaration must be seen.
class bar; // << Note the forward declaration
class foo{
public:
virtual void fooo(bar * b)=0;
}
class bar{
public:
virtual void barr(foo * f)=0;
}