# Removing LineNumberNodes when displaying expressions with macros
**URL:** https://discourse.julialang.org/t/removing-linenumbernodes-when-displaying-expressions-with-macros/20222
**Category:** General Usage
**Created:** [January 29, 2019, 9:23am UTC](https://discourse.julialang.org/t/removing-linenumbernodes-when-displaying-expressions-with-macros/20222 "2019-01-29T09:23:23Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@ffevotte](https://discourse.julialang.org/u/ffevotte)
#### Post date: [January 29, 2019, 9:23am UTC](https://discourse.julialang.org/t/removing-linenumbernodes-when-displaying-expressions-with-macros/20222/1 "2019-01-29T09:23:24Z")
I’m trying to define a function to filter `LineNumberNodes` from an expression to pretty-print it without annotations:
```julia
filterLNN(x) = deepcopy(x)
function filterLNN(e::Expr)
Expr(e.head, filterLNN.(filter(x->!isa(x, LineNumberNode), e.args))...)
end
```
```julia
julia> quote
let acc = 1
for i in 1:3
acc += i
end
acc
end
end |> filterLNN
quote
let acc = 1
for i = 1:3
acc += i
end
acc
end
end
```
So far, so good, but my problem is that macro calls in the expression aren’t displayed anymore:
```julia
julia> quote
let acc = 1
@simd for i in 1:3
acc += i
end
acc
end
end |> filterLNN
quote
let acc = 1
@simd
acc
end
end
```
I can display macro calls again if I leave at least their “accompanying” `LineNumberNode` in the expression:
```julia
function filterLNN(e::Expr)
if e.head == :macrocall
Expr(e.head, e.args[1:2]..., filterLNN.(filter(x->!isa(x, LineNumberNode), e.args[3:end]))...)
else
Expr(e.head, filterLNN.(filter(x->!isa(x, LineNumberNode), e.args))...)
end
end
```
```julia
julia> quote
let acc = 1
@simd for i in 1:3
acc += i
end
acc
end
end |> filterLNN
quote
let acc = 1
#= REPL[26]:3 =# @simd for i = 1:3
acc += i
end
acc
end
end
```
Is this expected behavior? Or should I look for a bug in the implementation of `display` for macro calls?
---
### Author:  [@mcabbott](https://discourse.julialang.org/u/mcabbott)
#### Post date: [January 29, 2019, 11:05am UTC](https://discourse.julialang.org/t/removing-linenumbernodes-when-displaying-expressions-with-macros/20222/2 "2019-01-29T11:05:46Z")
There is [MacroTools.rmlines](https://github.com/MikeInnes/MacroTools.jl/blob/master/src/utils.jl) which doesn’t actually seem to work on your quote. My hack was [here](https://github.com/mcabbott/TensorCast.jl/blob/master/src/pretty.jl) simply to regex the string version… but surely there is a nicer way.
---
### Author:  [@chakravala](https://discourse.julialang.org/u/chakravala)
#### Post date: [January 29, 2019, 11:32am UTC](https://discourse.julialang.org/t/removing-linenumbernodes-when-displaying-expressions-with-macros/20222/3 "2019-01-29T11:32:53Z")
You can also use my tool `SyntaxTree.linefilter!` from [SyntaxTree.jl](https://github.com/chakravala/SyntaxTree.jl) for that
```nohighlight
julia> using SyntaxTree
julia> quote
x = 1
y = x+2
end
quote
#= REPL[2]:2 =#
x = 1
#= REPL[2]:3 =#
y = x + 2
end
julia> linefilter!(ans)
quote
x = 1
y = x + 2
end
```
The `linefilter!` method is faster than MacroTools because it is recursively mutating
---
### Author:  [@ffevotte](https://discourse.julialang.org/u/ffevotte)
#### Post date: [January 29, 2019, 12:19pm UTC](https://discourse.julialang.org/t/removing-linenumbernodes-when-displaying-expressions-with-macros/20222/4 "2019-01-29T12:19:52Z")
> [@mcabbott](#):
>
> There is [MacroTools.rmlines](https://github.com/MikeInnes/MacroTools.jl/blob/master/src/utils.jl) which doesn’t actually seem to work on your quote
Thanks! It looks like `rmlines` removes only one level of `LineNumberNode`s; [`striplines`](https://github.com/MikeInnes/MacroTools.jl/blob/master/src/utils.jl#L72) is recursive. Both these seem to handle macro calls like in my implementation, but at least it’s an improvement to use an already written implementation instead of having to write mine.
> [@mcabbott](#):
>
> My hack was [here](https://github.com/mcabbott/TensorCast.jl/blob/master/src/pretty.jl) simply to regex the string version… but surely there is a nicer way.
Thanks. I’ll consider doing that too if I don’t find a nicer way.
---
### Author:  [@ffevotte](https://discourse.julialang.org/u/ffevotte)
#### Post date: [January 29, 2019, 12:24pm UTC](https://discourse.julialang.org/t/removing-linenumbernodes-when-displaying-expressions-with-macros/20222/5 "2019-01-29T12:24:48Z")
> [@chakravala](#):
>
> You can also use my tool `SyntaxTree.linefilter!` from [SyntaxTree.jl](https://github.com/chakravala/SyntaxTree.jl) for that.
Thanks, but this function does not seem to handle macro calls in any special way, and therefore produces the same output as my first attempt above:
```julia
julia> quote
let acc = 1
@simd for i in 1:3
acc += i
end
acc
end
end |> SyntaxTree.linefilter
quote
let acc = 1
@simd
acc
end
end
```
---
### Author:  [@chakravala](https://discourse.julialang.org/u/chakravala)
#### Post date: [January 29, 2019, 1:13pm UTC](https://discourse.julialang.org/t/removing-linenumbernodes-when-displaying-expressions-with-macros/20222/6 "2019-01-29T13:13:55Z")
Okay, I didnt test that, I will fix it later today since that’s a bug for me.
---
### Author:  [@chakravala](https://discourse.julialang.org/u/chakravala)
#### Post date: [January 29, 2019, 1:43pm UTC](https://discourse.julialang.org/t/removing-linenumbernodes-when-displaying-expressions-with-macros/20222/7 "2019-01-29T13:43:29Z")
> [@ffevotte](#):
>
> Thanks, but this function does not seem to handle macro calls in any special way, and therefore produces the same output as my first attempt above:
It is fixed in the `master` branch now, it can handle it correctly
```Julia
julia> quote
let acc = 1
@simd for i in 1:3
acc += i
end
acc
end
end |> SyntaxTree.linefilter!
quote
let acc = 1
@simd for i = 1:3
acc += i
end
acc
end
end
```
The problem is that `:macrocall` expressions now require a `LineNumberNode` or something to fill its place, so the solution is to simply put `nothing` in its place
>
This bug fix will be tagged as an updated release today
---
### Author:  [@Clemapfel](https://discourse.julialang.org/u/Clemapfel)
#### Post date: [January 8, 2022, 4:58pm UTC](https://discourse.julialang.org/t/removing-linenumbernodes-when-displaying-expressions-with-macros/20222/8 "2022-01-08T16:58:46Z")
I realize this is solved but for sport I figured I’ll write my own solution of `linefilter!` also using recursion, only tested in 1.7.1, maybe someone stumbling across this thread years later will find it useful:
Code:
```julia
macro unquote(expr::Expr)
function aux!(args::Vector{Any}) ::Nothing
to_delete = Vector{Integer}()
for (i, x) in enumerate(args)
if x isa LineNumberNode
push!(to_delete, i)
elseif x isa Expr
aux!(x.args)
end
end
n_deleted = 0;
for i in to_delete
deleteat!(args, i - n_deleted)
n_deleted += 1
end
end
aux!(expr.args)
return Expr(expr.head, :($(expr.args...)))
end
```
Usage:
```julia
julia> quoted = quote module m end; struct s end; i = 1; end
```
```julia
quote
#= REPL[15]:1 =#
module m
#= REPL[15]:1 =#
#= REPL[15]:1 =#
end
#= REPL[15]:1 =#
struct s
#= REPL[15]:1 =#
end
#= REPL[15]:1 =#
i = 1
end
```
```julia
julia> unquoted = @unquote quote module m end; struct s end; i = 1; end
```
```julia
quote
module m
end
struct s
end
i = 1
end
```
It is part of [jluna](https://github.com/Clemapfel/jluna) and can be used freely