Make a guess:

    _Y(Y), 
    _uu(),
    _ub(),
    _bu(),
    _bb()
{
    // example:
    //    form m (V,V,"mass",gamma, weight);  e.g. \int_\Gamma trace(u) trace(v) weight(x) ds     
    // with:
    //    geo omega ("square");
    //    geo gamma = omega["boundary"];
    //    V = space(omega,"P1");
    // Note: transform the domain gamma into a compacted-mesh for the 
    // evaluation of the weight
    form_init_on_domain (name, gamma, true, weight, compact(gamma), qopt);
}

}// namespace rheolef
# endif /* _RHEOLEF_FORM_WEIGHTED_H */