Jeffrey, Thanks, but my question was about how to have line and column in the error message. So I would like to have an error message like this:
ERROR: Failed to parse "error" as type Int64 in column 2, line 3. My best idea so far: catch the error at each level, and add i and line number. But this requires two try-catch-end blocks with rethrow. Extremely convoluted mess with rethrow here: https://gist.github.com/tpapp/6f67ff36a228f47a1792e011d9b0fc13 It does what I want, but it is ugly. A simpler solution would be appreciated. I am sure I am missing something. Best, Tamas On Thu, Nov 03 2016, Jeffrey Sarnoff wrote: > Tamas, > > running this > > > > typealias AkoString Union{String, SubString{String}} > > function parsefield{T <: Real, S <: AkoString}(::Type{T}, str::S) > result = T(0) > try > result = parse(T, str) > catch ArgumentError > errormsg = string("Failed to parse \"",str,"\" as type ", T) > throw(ErrorException(errormsg)) > end > return result > end > > function parserow(schema, strings) > # keep i for reporting column, currently not used > [parsefield(T, string) for (i, (T, string)) in enumerate(zip(schema, > strings))] > end > > function parsefile(io, schema) > line = 1 > while !eof(io) > strings = split(chomp(readline(io)), ';') > parserow(schema, strings) > line += 1 # currently not used, use for error reporting > end > end > > test_file = """ > 1;2;3 > 4;5;6 > 7;8;error > """ > > parsefile(IOBuffer(test_file), fill(Int, 3)) > > > > > by evaluating parsefile(...), results in > > > > julia> parsefile(IOBuffer(test_file), fill(Int, 3)) > ERROR: Failed to parse "error" as type Int64 > in parsefield(::Type{Int64}, ::SubString{String}) at ./REPL[2]:7 > in (::##1#2)(::Tuple{Int64,Tuple{DataType,SubString{String}}}) at > ./<missing>:0 > in collect_to!(::Array{Int64,1}, > ::Base.Generator{Enumerate{Base.Zip2{Array{DataType,1},Array{SubString{String},1}}},##1#2}, > ::Int64, ::Tuple{Int64,Tuple{Int64,Int64}}) at ./array.jl:340 > in > collect(::Base.Generator{Enumerate{Base.Zip2{Array{DataType,1},Array{SubString{String},1}}},##1#2}) > at ./array.jl:308 > in parsefile(::Base.AbstractIOBuffer{Array{UInt8,1}}, ::Array{DataType,1}) > at ./REPL[4]:5 > > > > > > On Wednesday, November 2, 2016 at 1:01:30 PM UTC-4, Tamas Papp wrote: >> >> This is a conceptual question. Consider the following (extremely >> stylized, but self-contained) code >> >> parsefield{T <: Real}(::Type{T}, string) = parse(T, string) >> >> function parserow(schema, strings) >> # keep i for reporting column, currently not used >> [parsefield(T, string) for (i, (T, string)) in enumerate(zip(schema, >> strings))] >> end >> >> function parsefile(io, schema) >> line = 1 >> while !eof(io) >> strings = split(chomp(readline(io)), ';') >> parserow(schema, strings) >> line += 1 # currently not used, use for error reporting >> end >> end >> >> test_file = """ >> 1;2;3 >> 4;5;6 >> 7;8;error >> """ >> >> parsefile(IOBuffer(test_file), fill(Int, 3)) >> >> This will fail with an error message >> >> ERROR: ArgumentError: invalid base 10 digit 'e' in "error" >> in tryparse_internal(::Type{Int64}, ::SubString{String}, ::Int64, >> ::Int64, ::Int64 >> , ::Bool) at ./parse.jl:88 >> in parse(::Type{Int64}, ::SubString{String}) at ./parse.jl:152 >> in parsefield(::Type{Int64}, ::SubString{String}) at ./REPL[152]:1 >> in (::##5#6)(::Tuple{Int64,Tuple{DataType,SubString{String}}}) at >> ./<missing>:0 >> in collect_to!(::Array{Int64,1}, >> ::Base.Generator{Enumerate{Base.Zip2{Array{DataTy >> pe,1},Array{SubString{String},1}}},##5#6}, ::Int64, >> ::Tuple{Int64,Tuple{Int64,Int64 >> }}) at ./array.jl:340 >> in >> collect(::Base.Generator{Enumerate{Base.Zip2{Array{DataType,1},Array{SubString{ >> >> String},1}}},##5#6}) at ./array.jl:308 >> in parsefile(::Base.AbstractIOBuffer{Array{UInt8,1}}, >> ::Array{DataType,1}) at ./RE >> PL[154]:5 >> >> Instead, I would like to report something like this: >> >> ERROR: Failed to parse "error" as Int on line 3, column 3. >> >> What's the idiomatic way of doing this in Julia? My problem is that >> parsefield fails without knowing line or column (i in parserow). I could >> catch and rethrow, constructing an error object gradually. Or I could >> pass line and column numbers to parserow and parsefield for error >> reporting, but that seems somehow inelegant (I have seen it in code >> though). >> >> Best, >> >> Tamas >>
