[Bug] Loading BSON variable with unit

[briochemc]

Here is a MWE Pluto notebook

### A Pluto.jl notebook ###
# v0.11.6

using Markdown
using InteractiveUtils

# ╔═╡ 665ea77a-e065-11ea-00f6-4bd4c96dd01e
using Unitful, BSON

# ╔═╡ 343a3f00-e067-11ea-0087-578bfebddeb2
ufoo = 3.0u"m/s"

# ╔═╡ 4725579e-e067-11ea-0fee-dbf660902683
BSON.@save "test.bson" ufoo

# ╔═╡ 4f79588c-e067-11ea-13eb-3bf5069dbf64
function get_ufoo()
	BSON.@load "test.bson" ufoo
	return ufoo
end

# ╔═╡ 5a2ccdea-e067-11ea-0169-712307d8649d
ubaz = get_ufoo() # This throws with "Unitful not defined"

# ╔═╡ Cell order:
# ╠═665ea77a-e065-11ea-00f6-4bd4c96dd01e
# ╠═343a3f00-e067-11ea-0087-578bfebddeb2
# ╠═4725579e-e067-11ea-0fee-dbf660902683
# ╠═4f79588c-e067-11ea-13eb-3bf5069dbf64
# ╠═5a2ccdea-e067-11ea-0169-712307d8649d

that throws

UndefVarError: Unitful not defined

    (::BSON.var"#29#30")(::Module, ::String)@extensions.jl:20
    BottomRF@reduce.jl:81[inlined]
    _foldl_impl(::Base.BottomRF{BSON.var"#29#30"}, ::Module, ::Array{Any,1})@reduce.jl:58
    foldl_impl@reduce.jl:48[inlined]
    mapfoldl_impl(::typeof(identity), ::BSON.var"#29#30", ::NamedTuple{(:init,),Tuple{Module}}, ::Array{Any,1})@reduce.jl:44
    #mapfoldl#204(::Base.Iterators.Pairs{Symbol,Module,Tuple{Symbol},NamedTuple{(:init,),Tuple{Module}}}, ::typeof(mapfoldl), ::Function, ::Function, ::Array{Any,1})@reduce.jl:160
    _mapreduce_dim@reducedim.jl:315[inlined]
    #mapreduce#[email protected]:310[inlined]
    #reduce#[email protected]:359[inlined]
    resolve(::Array{Any,1})@extensions.jl:20
    (::BSON.var"#33#34")(::Dict{Symbol,Any})@extensions.jl:53
    _raise_recursive(::Dict{Symbol,Any}, ::IdDict{Any,Any})@read.jl:79
    raise_recursive(::Dict{Symbol,Any}, ::IdDict{Any,Any})@read.jl:89
    (::BSON.var"#21#22"{IdDict{Any,Any}})(::Dict{Symbol,Any})@read.jl:94
    applychildren!(::BSON.var"#21#22"{IdDict{Any,Any}}, ::Array{Any,1})@BSON.jl:28
    raise_recursive@read.jl:94[inlined]
    (::BSON.var"#17#19"{IdDict{Any,Any}})(::Array{Any,1})@read.jl:79
    applychildren!(::BSON.var"#17#19"{IdDict{Any,Any}}, ::Dict{Symbol,Any})@BSON.jl:21
    _raise_recursive(::Dict{Symbol,Any}, ::IdDict{Any,Any})@read.jl:79
    raise_recursive(::Dict{Symbol,Any}, ::IdDict{Any,Any})@read.jl:89
    (::BSON.var"#17#19"{IdDict{Any,Any}})(::Dict{Symbol,Any})@read.jl:79
    applychildren!(::BSON.var"#17#19"{IdDict{Any,Any}}, ::Dict{Symbol,Any})@BSON.jl:21
    _raise_recursive(::Dict{Symbol,Any}, ::IdDict{Any,Any})@read.jl:79
    raise_recursive(::Dict{Symbol,Any}, ::IdDict{Any,Any})@read.jl:89
    (::BSON.var"#17#19"{IdDict{Any,Any}})(::Dict{Symbol,Any})@read.jl:79
    applychildren!(::BSON.var"#17#19"{IdDict{Any,Any}}, ::Dict{Symbol,Any})@BSON.jl:21
    _raise_recursive(::Dict{Symbol,Any}, ::IdDict{Any,Any})@read.jl:79
    raise_recursive(::Dict{Symbol,Any}, ::IdDict{Any,Any})@read.jl:89
    (::BSON.var"#43#44")(::Dict{Symbol,Any}, ::IdDict{Any,Any})@extensions.jl:138
    raise_recursive(::Dict{Symbol,Any}, ::IdDict{Any,Any})@read.jl:88
    (::BSON.var"#21#22"{IdDict{Any,Any}})(::Dict{Symbol,Any})@read.jl:94
    applychildren!(::BSON.var"#21#22"{IdDict{Any,Any}}, ::Array{Any,1})@BSON.jl:28
    raise_recursive@read.jl:94[inlined]
    (::BSON.var"#17#19"{IdDict{Any,Any}})(::Array{Any,1})@read.jl:79
    applychildren!(::BSON.var"#17#19"{IdDict{Any,Any}}, ::Dict{Symbol,Any})@BSON.jl:21
    _raise_recursive(::Dict{Symbol,Any}, ::IdDict{Any,Any})@read.jl:79
    raise_recursive(::Dict{Symbol,Any}, ::IdDict{Any,Any})@read.jl:89
    (::BSON.var"#43#44")(::Dict{Symbol,Any}, ::IdDict{Any,Any})@extensions.jl:138
    raise_recursive(::Dict{Symbol,Any}, ::IdDict{Any,Any})@read.jl:88
    (::BSON.var"#18#20"{IdDict{Any,Any}})(::Dict{Symbol,Any})@read.jl:82
    applychildren!(::BSON.var"#18#20"{IdDict{Any,Any}}, ::Dict{Symbol,Any})@BSON.jl:21
    _raise_recursive(::Dict{Symbol,Any}, ::IdDict{Any,Any})@read.jl:82
    raise_recursive(::Dict{Symbol,Any}, ::IdDict{Any,Any})@read.jl:89
    raise_recursive@read.jl:99[inlined]
    load@read.jl:104[inlined]
    macro expansion@BSON.jl:52[inlined]
    get_ufoo()@Other: 2
    top-level scope@Local: 1

I'm not wure why, since this works perfectly outside of Pluto, and it also works when using BSON but not Unitful... What's happening here? (FWIW, 'm trying to use Pluto with some data I have stored in BSON files with units.)

[fonsp]

Could you try this and see if the error is still there?

### A Pluto.jl notebook ###
# v0.11.6

using Markdown
using InteractiveUtils

# ╔═╡ 665ea77a-e065-11ea-00f6-4bd4c96dd01e
begin
	using Unitful, BSON
	Core.eval(Main, :(using Unitful))
end

# ╔═╡ 343a3f00-e067-11ea-0087-578bfebddeb2
ufoo = 3.0u"m/s"

# ╔═╡ 4725579e-e067-11ea-0fee-dbf660902683
BSON.@save "test.bson" ufoo

# ╔═╡ 4f79588c-e067-11ea-13eb-3bf5069dbf64
function get_ufoo()
	BSON.@load "test.bson" ufoo
	return ufoo
end

# ╔═╡ 5a2ccdea-e067-11ea-0169-712307d8649d
ubaz = get_ufoo() # This throws with "Unitful not defined"

# ╔═╡ Cell order:
# ╠═665ea77a-e065-11ea-00f6-4bd4c96dd01e
# ╠═343a3f00-e067-11ea-0087-578bfebddeb2
# ╠═4725579e-e067-11ea-0fee-dbf660902683
# ╠═4f79588c-e067-11ea-13eb-3bf5069dbf64
# ╠═5a2ccdea-e067-11ea-0169-712307d8649d

[fonsp]

It looks like BSON.jl has the limitation that it needs packages to be defined in the Main scope - it does not work inside modules when using external packages:

https://gist.github.com/fonsp/caef46b11c417014d0d1698b6b70607f#file-bsonunitful-jl

https://gist.github.com/fonsp/caef46b11c417014d0d1698b6b70607f#file-bsonunitful2-jl

🐟 fonsv/Desktop » julia bsonunitful.jl
ubaz = 3.0 m s^-1
🐟 fonsv/Desktop » julia bsonunitful2.jl
ERROR: LoadError: UndefVarError: Unitful not defined
Stacktrace:
 ...

Pluto runs your code inside 'workspace modules' so the line using Unitful, BSON is never executed in Main (only in Main.workspace42, Main.workspace43, etc).

[fonsp]

I don't know how BSON works, but maybe it can be fixed by running the extracting code at the place where BSON.@load is called, instead of running it inside Main.

[fonsp]

So this needs JuliaIO/BSON.jl#52 to be fixed

[briochemc]

Thanks @fonsp! Maybe it's worth mentioning that this can happen in the FAQ? (And include the Core.eval(Main, :(using MyPackage)) workaround?)

[fonsp]

No I think that this issue is a good enough resource on its own.

But maybe I should start making a big list of packages and their workarounds...

[fonsp]

Another option is to detect that a goofy package is being used, and show the link to the workaround inside the editor

[Tobias-Thomas]

I also encountered this problem recently, and yes the workaround with Core.eval(...) works, yet feels bad, especially when you need more than one package in there.
I think the "official workaround" is a bit easier, using the normal load function instead of the macro. It accepts a namespace as second argument, which defaults to Main. But when just using @__MODULE__ everything works as intended.
So, for the example above one would use: ufoo = BSON.load("test.bson", @__MODULE__)[:ufoo]

Just writing this here, because this issue was the first link when searching for this BSON related problem in conjunction with Pluto.