# Function definition throwing UndefVarError

**URL:** <https://discourse.julialang.org/t/function-definition-throwing-undefvarerror/56845>\
**Category:** New to Julia\
**Tags:** question, error-message\
**Created:** [March 10, 2021, 1:46am UTC](https://discourse.julialang.org/t/function-definition-throwing-undefvarerror/56845 "2021-03-10T01:46:51Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![MattWillFlood](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mattwillflood/32/20722_2.png) [@MattWillFlood](https://discourse.julialang.org/u/MattWillFlood)\
**Post date:** [March 10, 2021, 1:46am UTC](https://discourse.julialang.org/t/function-definition-throwing-undefvarerror/56845/1 "2021-03-10T01:46:51Z")

</div>

Hello,

I have a function which follows the condensed, simplified format shown below.

```julia
using Statistics: std, mean, median, var
function foo(a,b,c)
"""
Do some stuff 
"""

if a > 0
    if a == 1
        bar(x) = std(x, corrected=false)
    elseif a == 2
        bar(x) = var(x, corrected=false)
    elseif a == 3
        bar(x) = mean(abs.(x .- mean(x)))
    elseif a == 4
        bar(x) = median(abs.(x .- median(x)))    
    end
else
    """
    Do some other stuff instead
    """
end

return c*bar(b)
end

```

When I call the `foo` function for `a = 0` or `a = 1`, it runs fine.  
However, for `a > 2` an error message appears for an undefined variable:  
`ERROR: UndefVarError: bar not defined`

Each of these `bar` functions runs normally when called in the REPL…

Can anyone tell me why I might be getting this error for `a` values greater than 1? 🤷🏽‍♂️

Thanks for your help 👍🏼 😊

---

<div class="post-metadata">

**Author:** ![rdeits](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/rdeits/32/286_2.png) [@rdeits](https://discourse.julialang.org/u/rdeits)\
**Post date:** [March 10, 2021, 3:11am UTC](https://discourse.julialang.org/t/function-definition-throwing-undefvarerror/56845/2 "2021-03-10T03:11:50Z")

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Wow, that’s really weird. Even worse is that even if you didn’t get an `UndefVarError`, you’d still get the wrong answer due to the issue discussed here: [Conditional function definition](https://discourse.julialang.org/t/conditional-function-definition/27348)

The fix for both problems is to use an anonymous function:

```julia
using Statistics: std, mean, median, var
function foo(a,b,c)
    """
    Do some stuff 
    """

    if a > 0
        if a == 1
            bar = x -> std(x, corrected=false)
        elseif a == 2
            bar = x -> var(x, corrected=false)
        elseif a == 3
            bar = x -> mean(abs.(x .- mean(x)))
        elseif a == 4
            bar = x -> median(abs.(x .- median(x)))    
        end
    else
        """
        Do some other stuff instead
        """
    end

    return c*bar(b)
end

```

(this will still error unless `a` is 1, 2, 3, or 4, in which case `bar` really is undefined.)

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<div class="post-metadata">

**Author:** ![MattWillFlood](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mattwillflood/32/20722_2.png) [@MattWillFlood](https://discourse.julialang.org/u/MattWillFlood)\
**Post date:** [March 10, 2021, 3:34pm UTC](https://discourse.julialang.org/t/function-definition-throwing-undefvarerror/56845/3 "2021-03-10T15:34:20Z")

</div>

Brilliant, thanks a mil @rdeits 🙌🏼 👍🏼  
The anonymous functions work now.

I wonder why my original approach didn’t work though…