// Note `XPython` is the name for the Boost Python bindings class of `X`.

void BazPython::RunThatFoo(const bp::object & foo) {
    FooPython & foo_obj = bp::extract<FooPython&>(foo);
    auto ps_ptr = foo_obj.GetPSPtr();
    Baz::DoPSComputation(ps_ptr);  // Expects a `const std::shared_ptr<planning_scene::PlanningScene>`
}

class PlanningScene : private boost::noncopyable, public std::enable_shared_from_this<PlanningScene>

std::shared_ptr<planning_scene::PlanningScene> Foo::GetPSPtr() {  // two different attempts shown
    // return ps_;
    return (*ps_).shared_from_this();
}