# What is the best way to use a module inside a function

**URL:** <https://discourse.julialang.org/t/what-is-the-best-way-to-use-a-module-inside-a-function/33285>\
**Category:** General Usage\
**Tags:** question\
**Created:** [January 13, 2020, 1:46am UTC](https://discourse.julialang.org/t/what-is-the-best-way-to-use-a-module-inside-a-function/33285 "2020-01-13T01:46:34Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![asavasci](https://avatars.discourse-cdn.com/v4/letter/a/eb8c5e/32.png) [@asavasci](https://discourse.julialang.org/u/asavasci)\
**Post date:** [January 13, 2020, 1:46am UTC](https://discourse.julialang.org/t/what-is-the-best-way-to-use-a-module-inside-a-function/33285/1 "2020-01-13T01:46:34Z")

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I am not able to use the function syntax below

```julia
function f()
        using DataFrames
        return Dataframe(x=[1,2],y=[3,4])
end

```

gives `syntax: "using" expression not at top level` error message, I searched the error message, but wasn’t able to implement the solution because it is related to writing module. To work around this limitation temporarily I wrote the function as

```julia
function f()   
    return Dict(x=>[1,2],y=>[3,4])    
end

```

However, the former function structure is more efficient to my work, how can I use it?

---

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**Author:** ![PetrKryslUCSD](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/petrkryslucsd/32/215825_2.png) [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Post date:** [January 13, 2020, 2:42am UTC](https://discourse.julialang.org/t/what-is-the-best-way-to-use-a-module-inside-a-function/33285/2 "2020-01-13T02:42:23Z")

</div>

Module cannot be defined inside a function. The keyword `using` cannot be used inside of function. What I usually do is something like this:

```julia
module mmmmPoiss_energy
using FinEtools
using FinEtoolsHeatDiff
using Test
import LinearAlgebra: cholesky
function test()
  A = 1.0 # dimension of the domain (length of the side of the square)
  thermal_conductivity = [i==j ? one(FFlt) : zero(FFlt) for i=1:2, j=1:2]; # conductivity matrix
  Q = -6.0; # internal heat generation rate
  function getsource!(forceout::FFltVec, XYZ::FFltMat, tangents::FFltMat, fe_label::FInt)
    forceout[1] = Q; #heat source
  end
  N = 2;# number of subdivisions along the sides of the square domain
...
  true
end
end
using .mmmmPoiss_energy
mmmmPoiss_energy.test()

```

That is I define a module with functions and such in order to protect the global environment from anything that I wish to define, and conversely to protect the things I wish to define from inadvertently using variables in the global environment. So your use case might be handled as:

```julia
module m1
using DataFrames
function f()
        return DataFrame(x=[1,2],y=[3,4])
end
end
using .m1
m1.f()

```

---

<div class="post-metadata">

**Author:** ![asavasci](https://avatars.discourse-cdn.com/v4/letter/a/eb8c5e/32.png) [@asavasci](https://discourse.julialang.org/u/asavasci)\
**Post date:** [January 13, 2020, 4:19am UTC](https://discourse.julialang.org/t/what-is-the-best-way-to-use-a-module-inside-a-function/33285/3 "2020-01-13T04:19:17Z")

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Thanks for the reply. Now, I want to keep the module file separately, and import to the main code block. I did this by the following piece of code

```julia
include("m1_module_file")
using .m1

```

Is there a way to use module file just by writing `using .m1` without adding line `include(...)` ?

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<div class="post-metadata">

**Author:** ![StefanKarpinski](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stefankarpinski/32/24_2.png) [@StefanKarpinski](https://discourse.julialang.org/u/StefanKarpinski)\
**Post date:** [January 13, 2020, 5:19am UTC](https://discourse.julialang.org/t/what-is-the-best-way-to-use-a-module-inside-a-function/33285/4 "2020-01-13T05:19:31Z")

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Not yet: [https://GitHub.com/JuliaLang/Julia/issues/4600](https://GitHub.com/JuliaLang/Julia/issues/4600)