Plumbing a shower and tub drain together?

I have a tub and want to add a shower. Is it good practice to plumb both ahead of a common drain bucket?

 

I wonder if he/she means a drum trap?

 

I am not sure what the correct term for the plumbing (P-Trap?) that provides the vapor barrier for a tub drain. It is below grade (under the slab) so I can not see it. All that is visible is the tub drain run down thru the concrete. So I want to tee a shower drain in just above the concrete level.

 

no go. two drains, two P traps. Back to the drawing board.

And then, here's more:
-- -- separate connections to the stack or else separate venting.

lots to learn.

david