# Errors when re-including modules in REPL

**URL:** <https://discourse.julialang.org/t/errors-when-re-including-modules-in-repl/30323>\
**Category:** New to Julia\
**Created:** [October 26, 2019, 12:31am UTC](https://discourse.julialang.org/t/errors-when-re-including-modules-in-repl/30323 "2019-10-26T00:31:06Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![jbu](https://avatars.discourse-cdn.com/v4/letter/j/a8b319/32.png) [@jbu](https://discourse.julialang.org/u/jbu)\
**Post date:** [October 26, 2019, 12:31am UTC](https://discourse.julialang.org/t/errors-when-re-including-modules-in-repl/30323/1 "2019-10-26T00:31:06Z")

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Here’s a minimum working example of the problem I’ve been having. I’m using the Julia v1.1 REPL in Ubuntu Linux 16.04. Suppose I have the following file called `moduletest.jl`:

```julia
module mymodule
    struct mystruct
        myint::Int
    end

    function myfunction(x::mystruct)
        println(x.myint)
    end
end

```

In the REPL I include this file, create an instance of `mystruct`, and call `myfunction`:

```julia
julia> include("moduletest.jl")
Main.mymodule

julia> thisstruct = mymodule.mystruct(1)
Main.mymodule.mystruct(1)

julia> mymodule.myfunction(thisstruct)
1

```

Now if I reinclude the file `moduletest.jl` (without changing or redefining `thisstruct`) and call the function `myfunction` again, I get the following error:

```julia
julia> include("moduletest.jl")
WARNING: replacing module mymodule.
Main.mymodule

julia> mymodule.myfunction(thisstruct)
ERROR: MethodError: no method matching myfunction(::Main.mymodule.mystruct)
Closest candidates are:
  myfunction(::Main.mymodule.mystruct) at /media/james/Data/Box Sync/Code/QP_synth/moduletest.jl:11
Stacktrace:
 [1] top-level scope at none:0

```

To the best of my knowledge, the error is arising because it thinks that `thisstruct` has the wrong type. When I check the type of `thisstruct` however, I see the following:

```julia
julia> typeof(thisstruct)
Main.mymodule.mystruct

```

The type looks exactly the same as the type listed in the “Closest candidates” error message. This can be really confusing. If I redefine `thisstruct` _after_ the second `include` statement then the function works perfectly. However, I tend to make a lot of incremental edits to modules and reinclude them frequently to test if the changes work. I’d prefer not have to reinstantiate all of my struct instances every time I reinclude a module (if possible). I’d also rather not restart the REPL if possible since it takes a while to reimport all the other packages I’m using. So my questions are:

1. What’s the best way to reinclude modules in a REPL without running into this issue?
2. Would it be possible to change the error message for this situation to be more clear about what the problem is?

* * *

(Other details if they’re helpful:

- I’m fairly new to Julia, so I apologize if I’m not understanding something basic here.
- I tried the minimum example with the [Revise.jl](https://github.com/timholy/Revise.jl) package (v2.1.0) and had the same problem occur.)

---

<div class="post-metadata">

**Author:** ![Tamas\_Papp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tamas_papp/32/25949_2.png) [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Post date:** [October 26, 2019, 11:43am UTC](https://discourse.julialang.org/t/errors-when-re-including-modules-in-repl/30323/2 "2019-10-26T11:43:56Z")

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The type of `thisstruct` is technically not the same type when you redefine the module:

```julia

julia> include("/tmp/moduletest.jl")
Main.mymodule

julia> thisstruct = mymodule.mystruct(1)
Main.mymodule.mystruct(1)

julia> include("/tmp/moduletest.jl")
WARNING: replacing module mymodule.
Main.mymodule

julia> typeof(thisstruct) ≡ mymodule.mystruct
false

```

even though it does not show when printed. It is the type from the previous incarnation of that module.

The solution is not to reload modules, but use Revise.jl. Then you get a smoother experience.

Incidentally, I would recommend following the common Julia style conventions, eg [capitalizing types](https://docs.julialang.org/en/v1/manual/style-guide/#Use-naming-conventions-consistent-with-Julia-base/-1).

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<div class="post-metadata">

**Author:** ![jbu](https://avatars.discourse-cdn.com/v4/letter/j/a8b319/32.png) [@jbu](https://discourse.julialang.org/u/jbu)\
**Post date:** [October 26, 2019, 9:26pm UTC](https://discourse.julialang.org/t/errors-when-re-including-modules-in-repl/30323/3 "2019-10-26T21:26:01Z")

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Perfect–I’ll use Revise.jl instead then. Thanks also for the link on Julia styling conventions!