no method +(Int64, Nothing) when writing strings that have been split

[swadey]

When writing out to a file, I get:

ERROR: no method +(Int64, Nothing)
 in write at io.jl:61
 in write at io.jl:391
 in include at boot.jl:244
 in include_from_node1 at loading.jl:128
while loading /Users/swade/projects/julia/test.jl, in expression starting on line 10

Here's a minimized code example:

names = (String)[]

inf = open("test.jl")
for i in eachline(inf)
  push!(names, split(i, r"\s+")[1]) # NOTE: split call, doesn't raise error without it
end
close(inf)

f = open("test.bin", "w")
write(f, names)
close(f)

[swadey]

Seems to be related to writing of SubString

[ihnorton]

How so? We've seen some other SubString weirdness recently so if you have an example/test case it might be helpful.

[Keno]

Well, it seems quite clear that one of the write methods is not returning the number of bytes written as it should.

[swadey]

OK, here's a simpler example:

julia> a = ["1", "2", "3"]
3-element Array{ASCIIString,1}:
 "1"
 "2"
 "3"

julia> open("test.out", "w") do f write(f, a) end
3

julia> a = split(strip("1 2 3"), r"\s+")
3-element Array{SubString{ASCIIString},1}:
 "1"
 "2"
 "3"

julia> open("test.out", "w") do f write(f, a) end
ERROR: no method +(Int64, Nothing)
 in write at io.jl:61
 in write at io.jl:391
 in anonymous at none:1
 in open at io.jl:373

julia> open("test.out", "w") do f x = write(f, a[1]::SubString{ASCIIString}); println(x) end
nothing

I'm guessing that this is an invariance problem, i.e. SubString{ASCIIString} isn't the same as SubString{ByteString}?

[kmsquire]

Good call, @loladiro: https://github.com/JuliaLang/julia/blob/master/base/string.jl#L68