julia> x = Vector{Real}(undef, 2)
2-element Vector{Real}:
#undef
#undef
julia> @set! x[1] = 1.0
ERROR: UndefRefError: access to undefined reference
Stacktrace:
[1] getindex
@ ./array.jl:801 [inlined]
[2] copy!(dst::Vector{Real}, src::Vector{Real})
@ Base ./abstractarray.jl:827
[3] setindex
@ ~/.julia/packages/Setfield/XM37G/src/setindex.jl:9 [inlined]
[4] set(obj::Vector{Real}, l::Setfield.IndexLens{Tuple{Int64}}, val::Float64)
@ Setfield ~/.julia/packages/Setfield/XM37G/src/lens.jl:181
[5] top-level scope
@ ~/.julia/packages/Setfield/XM37G/src/sugar.jl:182It correctly works when eltype isbitstype since then you don't end up with undef but instead an "unitialized" value, for example
julia> x = Vector{Float32}(undef, 2)
2-element Vector{Float32}:
1.0f-45
1.7f-44
julia> @set! x[1] = 1.0
2-element Vector{Float64}:
1.0
1.6815581571897805e-44Maybe the way to go is:
Base.@propagate_inbounds function setindex(xs::AbstractArray, v, I...)
T = promote_type(eltype(xs), typeof(v))
ys = similar(xs, T)
if isbitstype(T)
copy!(ys, xs)
elseif eltype(xs) !== Union{}
for index in CartesianIndices(xs)
if isassigned(xs, Tuple(index)...)
ys[index] = xs[index]
end
end
end
ys[I...] = v
return ys
end? Seems sub-optimal though.
This is not an urgent issue to resolve for our sake, but figured I'd at least raise it here for now. In the meantime (and this is what we'll do anyways as it aligns better with the behavior we want) one can use BangBang.@set!! which uses BangBang.prefermutation instead of identity in setmacro.
It correctly works when
eltypeisbitstypesince then you don't end up withundefbut instead an "unitialized" value, for exampleMaybe the way to go is:
? Seems sub-optimal though.
This is not an urgent issue to resolve for our sake, but figured I'd at least raise it here for now. In the meantime (and this is what we'll do anyways as it aligns better with the behavior we want) one can use
BangBang.@set!!which usesBangBang.prefermutationinstead ofidentityinsetmacro.