Namespacing of methods

Internals & Design
2

Nice resume, all that seems perfectly correct (and helpful).

I think the way to think about these things is about namespaces.

import A: func brings func to the namespace where that was executed. If that namespace is module B, then B.func is available. If inside module B you add export func now, func is available where using B was executed.

using A will put then func into the current namespace if it is exported in A (the same thing as above). If that was executed inside module B, now B.func exists.

import A does not bring A.func into the namespace, thus if that was executed inside module B, there will be no B.func.

(I don’t think you can import or export one method but not the other, of the same function. That is one of the reasons type piracy is highly discouraged).

Concerning the “bug”: actually the problem there is that Julia does not complain of a module exporting something that is not defined (it can’t really do that, because the module is parsed sequentially, thus it cannot know if there will be a definition later). A linter could possibly do that. But here the REPL does not seem to try to autocomplete, while B.<tab> does (with a stranger name that does not overlap with any other function that is clearer):

julia> module B
           export foobar
       end
Main.B

julia> foo # tab (nothing appears)

julia> B.foobar # does autocomplete
ERROR: UndefVarError: foobar not defined
Stacktrace:
 [1] getproperty(x::Module, f::Symbol)
   @ Base ./Base.jl:35
 [2] top-level scope
   @ REPL[2]:1
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