Do you have any suggestions for project directory structure?

[Orfeo]

Suppose I have a project "protocols" that uses DMock and a  
library Foo.
I would like to use a structure dub style..Which solution is 
better:

A.

protocols
  ├── bin
  │   └── protocols.a
  ├── dmocks
  │   └── *.d
  ├── foo
  │   └── *.d
  ├── src
  │   └── protocols
  │       └── *.d

B.

protocols
  ├── bin
  │   └── protocols.a
  ├── src
  │   ├── dmocks
  │   │    └── *.d
  │   ├── foo
  │   │    └── *.d
  │   └── protocols
  │        └── *.d


Or another solution?
Thanks