`using` an inner module with its symbol, in a nested structure of modules

Question

I have a nested structure of modules like this:

module TestMod
  module B
    export BB
    module BB

    end
  end
  module C
    module D
      #using ...B
      importall ...B 
      using BB # => ERROR: ArgumentError: Module BB not found in current path.
    end
  end
end

I want to do using BB in module D but it seems that the only way is to write a full path for BB (e.g. using B.BB), both import or using do not help.

Answer 1

Once you've usinged B, you can do a relative import from the current module to any exported modules of B, including BB. See

julia> module TestMod
         module B
           export BB
           module BB
             x = 2
             export x
           end
         end
         module C
           module D
             using ...B 
             using .BB
             println(x)
           end
         end
       end
2
TestMod

The syntax using .BB means to use the module with name BB in the current module, whereas using BB means using top-level module BB; that is, it will look for Main.BB, which is not what you want.