# Setting default arguments for a function passed to another function
**URL:** https://discourse.julialang.org/t/setting-default-arguments-for-a-function-passed-to-another-function/100712
**Category:** General Usage
**Created:** [June 22, 2023, 7:57pm UTC](https://discourse.julialang.org/t/setting-default-arguments-for-a-function-passed-to-another-function/100712 "2023-06-22T19:57:02Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@dlcole3](https://discourse.julialang.org/u/dlcole3)
#### Post date: [June 22, 2023, 7:57pm UTC](https://discourse.julialang.org/t/setting-default-arguments-for-a-function-passed-to-another-function/100712/1 "2023-06-22T19:57:02Z")
I am defining a function that takes a keyword argument. I am setting a default function for this keyword argument, but I would like to also pass a default keyword to that second function. I am not sure how to do this.
For example, I would like to have something like:
```julia
function foo(X; fn = Statistics.mean)
fn(X)
end
```
However, I would like to also set as a default the keyword argument `dims = 1` for `Statistics.mean`. In other words, if the user calls `foo(X)`, I want it to return `Statistics.mean(x; dims = 1)`. As a user may pass a function that does not take a keyword argument `dims = 1`, I cannot add that directly to the line where `fn` is called. Is there a way to set a default argument of a default function on a keyword argument?
---
### Author:  [@frylock](https://discourse.julialang.org/u/frylock)
#### Post date: [June 22, 2023, 8:13pm UTC](https://discourse.julialang.org/t/setting-default-arguments-for-a-function-passed-to-another-function/100712/2 "2023-06-22T20:13:44Z")
First, welcome!
You can just pass keyword arguments to the alias(?) name. You could also just trap the error if it is thrown if the user passes in a function that doesn’t have the needed keyword. Not necessarily a great way to do it, but if it absolutely needs to be designed this way …
```julia
function bar(X; baz)
println("barring $X with $baz")
end
function zap(X)
println("zapping $X")
end
function foo(X; fn=bar)
try
fn(X, baz="hi")
catch e
if isa(e, MethodError)
@warn "you probably need to pass in a `fn` that has a `baz` keyword?"
end
end
end
foo(3)
foo(3, fn=zap)
```
prints:
```julia
barring 3 with hi
┌ Warning: you probably need to pass in a `fn` that has a `baz` keyword?
└ @ Main ~/Projects/Julia_C/C/stuff.jl:14
```
---
### Author:  [@bertschi](https://discourse.julialang.org/u/bertschi)
#### Post date: [June 22, 2023, 8:35pm UTC](https://discourse.julialang.org/t/setting-default-arguments-for-a-function-passed-to-another-function/100712/3 "2023-06-22T20:35:03Z")
If the default keyword argument only applies to the default function, just define that function accordingly, i.e.,
```julia
default_mean(x) = Statistics.mean(x; dims = 1)
function foo(X; fn = default_mean) fn(X) end
```
or simply
```julia
foo(X; fn = arg -> Statistics.mean(arg; dims = 1)) = fn(X)
```
---
### Author:  [@dlcole3](https://discourse.julialang.org/u/dlcole3)
#### Post date: [June 22, 2023, 8:43pm UTC](https://discourse.julialang.org/t/setting-default-arguments-for-a-function-passed-to-another-function/100712/4 "2023-06-22T20:43:55Z")
Thank you. That works great