How do I limited revolute joint (not classic)

Hi. I know that physics limited revolute joint work this way (if I use -45°,45° limits):

or

But I want to make it work this way:

So the initial angle limits is from another object. How can I do this? (sorry for my bad english, I hope you understand)

ok I think I found solution

lower limit: -(anglediff((parent_object.Angle+45),child_object.Angle))

upper limit: anglediff((parent_object.Angle-45),child_object.Angle)

This is exactly what I was looking at trying to do. Am building a rope-like thing and it can be spawned at any angle. Since there's not differentiation between local/global in co-ordinates system, trying to figure out limited joints relative to others is a headache!