# Include mystery
**URL:** https://discourse.julialang.org/t/include-mystery/22360
**Category:** General Usage
**Created:** [March 26, 2019, 4:20pm UTC](https://discourse.julialang.org/t/include-mystery/22360 "2019-03-26T16:20:11Z")
**Posts on this page:** 12
**Page:** 1
### Author:  [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)
#### Post date: [March 26, 2019, 4:20pm UTC](https://discourse.julialang.org/t/include-mystery/22360/1 "2019-03-26T16:20:11Z")
I have two files. The first includes the second. The compiler complains about the variable `var` not being defined in the second file. Why?
First file:
```julia
function a()
var = 1;
include("b.jl")
end
a()
```
Second file:
```julia
@show var
```
When I run `include("a.jl")` I get:
```julia
ERROR: LoadError: LoadError: UndefVarError: var not defined
Stacktrace:
...
```
---
### Author:  [@kristoffer.carlsson](https://discourse.julialang.org/u/kristoffer.carlsson)
#### Post date: [March 26, 2019, 4:23pm UTC](https://discourse.julialang.org/t/include-mystery/22360/2 "2019-03-26T16:23:22Z")
Because things are evaluated into global scope (where there is no `var`).
---
### Author:  [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)
#### Post date: [March 26, 2019, 4:28pm UTC](https://discourse.julialang.org/t/include-mystery/22360/3 "2019-03-26T16:28:11Z")
I’m not sure I follow. I thought that the compiler would simply slurp the contents of the included file.
Evaluation of `include("a.jl")` goes through without a hitch. But then when I run, there is the error.
I find that confusing. I thought the embedded file `b.jl` would simply become part of the code that defines the function `a`?
EDIT: Actually I meant evaluation of
```julia
function a()
var = 1;
include("b.jl")
end
```
This works with no problems.
---
### Author:  [@mbauman](https://discourse.julialang.org/u/mbauman)
#### Post date: [March 26, 2019, 4:31pm UTC](https://discourse.julialang.org/t/include-mystery/22360/4 "2019-03-26T16:31:07Z")
[https://docs.julialang.org/en/v1/base/base/#Base.include](https://docs.julialang.org/en/v1/base/base/#Base.include)
> Evaluate the contents of the input source file in the global scope
Include is just another function. You’re not running it by defining the function.
---
### Author:  [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)
#### Post date: [March 26, 2019, 4:31pm UTC](https://discourse.julialang.org/t/include-mystery/22360/5 "2019-03-26T16:31:36Z")
I think I’m beginning to see the light. The compiler doesn’t actually copy the contents
of the included file into the function, but does this:
```julia
julia> @code_lowered a()
CodeInfo(
1 ─ var = 1
│ (Main.include)("b.jl")
│ %3 = Main.hey
│ value = %3
│ %5 = (Base.repr)(%3)
│ (Base.println)("hey = ", %5)
└── return value
)
```
In other words, the inclusion of the file is in the code of `a`.
---
### Author:  [@kristoffer.carlsson](https://discourse.julialang.org/u/kristoffer.carlsson)
#### Post date: [March 26, 2019, 4:31pm UTC](https://discourse.julialang.org/t/include-mystery/22360/6 "2019-03-26T16:31:58Z")
> [@PetrKryslUCSD](#):
>
> I thought that the compiler would simply slurp the contents of the included file.
What can I say, that was a wrong assumption. It parses it and evaluates the expression (and evals go into the current global scope unless given another module).
---
### Author:  [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)
#### Post date: [March 26, 2019, 4:33pm UTC](https://discourse.julialang.org/t/include-mystery/22360/7 "2019-03-26T16:33:17Z")
So is there any way I could get that behavior: I am motivated by having a piece of code that I would like to incorporate into multiple pieces “by inclusion” instead of by defining a function and calling that function?
I suppose I am looking for a macro?
---
### Author:  [@kristoffer.carlsson](https://discourse.julialang.org/u/kristoffer.carlsson)
#### Post date: [March 26, 2019, 4:33pm UTC](https://discourse.julialang.org/t/include-mystery/22360/8 "2019-03-26T16:33:51Z")
> [@Is "include" safe to use inside a function?](https://discourse.julialang.org/t/is-include-safe-to-use-inside-a-function/10867):
>
> Is the following safe to do? #testinclude.jl a = 2 julia\> function f() include("testinclude.jl") return a end f (generic function with 1 method) julia\> f() 2
It has a macro for this.
---
### Author:  [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)
#### Post date: [March 26, 2019, 4:36pm UTC](https://discourse.julialang.org/t/include-mystery/22360/9 "2019-03-26T16:36:07Z")
Good find. No mystery after all 🙂 Thanks.
---
### Author:  [@mbauman](https://discourse.julialang.org/u/mbauman)
#### Post date: [March 26, 2019, 4:37pm UTC](https://discourse.julialang.org/t/include-mystery/22360/10 "2019-03-26T16:37:31Z")
This misconception probably isn’t entirely your doing. Folks (maybe including myself?) have often talked about `include` as a “copy-pasting” of code when discouraging others from trying to use it as a pseudo-packaging mechanism. It may be worth trying to steer away from that mental model.
---
### Author:  [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)
#### Post date: [March 26, 2019, 4:39pm UTC](https://discourse.julialang.org/t/include-mystery/22360/11 "2019-03-26T16:39:03Z")
Indeed, you’re right. That’s the soundbite I remembered.
---
### Author:  [@greg\_plowman](https://discourse.julialang.org/u/greg_plowman)
#### Post date: [March 27, 2019, 4:41am UTC](https://discourse.julialang.org/t/include-mystery/22360/12 "2019-03-27T04:41:58Z")
I must confess to being tripped up by misunderstanding exactly what `include` does. Indeed, I think it is a common misconception.
I can’t help but feel that it is partly due to the name `include` which might be associated with pre-processor directives in other languages. And it is commonly used for the same or similar functionality.
For me the name `eval_file` would help remind me that it is a normal function executed at run time and which `eval`s the contents of the file (in global scope since it is a normal function). Similarly, `include_string` could be named `eval_string`.