# Using multiple modules in a package

**URL:** <https://discourse.julialang.org/t/using-multiple-modules-in-a-package/50705>\
**Category:** Tooling\
**Tags:** package\
**Created:** [November 24, 2020, 6:38pm UTC](https://discourse.julialang.org/t/using-multiple-modules-in-a-package/50705 "2020-11-24T18:38:03Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![GlenHenshaw](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/glenhenshaw/32/5269_2.png) [@GlenHenshaw](https://discourse.julialang.org/u/GlenHenshaw)\
**Post date:** [November 24, 2020, 6:38pm UTC](https://discourse.julialang.org/t/using-multiple-modules-in-a-package/50705/1 "2020-11-24T18:38:03Z")

</div>

I’ve been coding in Julia for a while but only recently have I started developing packages. Right now I’ve activated a new environment, called A. Environment A wants to define a package, also called A, and so there is a file names A.jl under the A/src directory. A, in turn, needs to use modules B, C, and D, so there are also B.jl, C.jl, and D.jl files under source, and A.jl consists solely of

```
module A
   include("B.jl")
   include("C.jl")
   include("D.jl")
end

```

when I try “using A” I get the following error:

```
julia> using A
[Info: Precompiling A [376ac33e-dbe2-4852-b43b-cb274be2c3c1]
ERROR: LoadError: LoadError: ArgumentError: Package A does not have B in its dependencies:
- If you have A checked out for development and have
  added B as a dependency but haven't updated your primary
  environment's manifest file, try `Pkg.resolve()`.
- Otherwise you may need to report an issue with A

```

…and I am stumped. B is not a package, it’s just a file defining a module. What am I doing wrong?

---

<div class="post-metadata">

**Author:** ![Zhong\_Pan](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/zhong_pan/32/19872_2.png) [@Zhong\_Pan](https://discourse.julialang.org/u/Zhong_Pan)\
**Post date:** [November 24, 2020, 7:00pm UTC](https://discourse.julialang.org/t/using-multiple-modules-in-a-package/50705/2 "2020-11-24T19:00:19Z")

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Check your current work directory by inserting “println(pwd())” before the include statements. It is possible that the current work directory is not the same path these files are stored at. Current work directory really depends on where you started the Julia process and whether you have switched directory after that.

If you want to make sure Julia looks for B.jl etc. at the same path as the file A.jl, you can try this:

```julia
module A
   include(joinpath(@ __DIR__ , "B.jl"))
   include(joinpath(@ __DIR__ , "C.jl"))
   include(joinpath(@ __DIR__ , "C.jl"))
end

```

`@ __DIR__ ` will expand to the path where the current file is.

`@ __DIR__ ` works well for me except in one situation: if you want to build an app using PackageCompiler and distribute that to other machines, be careful that `@ __DIR__ ` will expand to an absolute path in your development machine during compilation, which may not match the path on the target machine.

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<div class="post-metadata">

**Author:** ![fredrikekre](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fredrikekre/32/1688_2.png) [@fredrikekre](https://discourse.julialang.org/u/fredrikekre)\
**Post date:** [November 24, 2020, 9:14pm UTC](https://discourse.julialang.org/t/using-multiple-modules-in-a-package/50705/3 "2020-11-24T21:14:39Z")

</div>

> [@GlenHenshaw](#):
>
> `ERROR: LoadError: LoadError: ArgumentError: Package A does not have B in its dependencies:`

This means that (most likely) somewhere in the module `A` there is a `using B`. `using B` essentially mean “load the external package `B`”, but what you want here is probably “load the local module `B`” , right? To achieve that you need to use `using .B` instead (note the dot) which looks for the `B` module in the _current scope_ (e.g. the `A` module).

What Zhong\_Pan said is not relevant; `include("B.jl")` _always_ means `include(joinpath(@ __DIR__ , "B.jl"))`.