looking for simpler solution: how to report context for an error

demo.jl

type ParseErrorLoc
    T
    string
    column
    line
end

function Base.show(io::IO, pel::ParseErrorLoc)
    print("could not parse \"$(pel.string)\" as $(pel.T)")
    if pel.column > 0
        print(" in column $(pel.column)")
        if pel.line > 0
            print(" in line $(pel.line)")
        end
    end
    println()
end

function parsefield{T <: Real}(::Type{T}, string)
    try parse(T, string)
    catch e
        if isa(e, ArgumentError)
            throw(ParseErrorLoc(T, string, -1, -1))
        else
            rethrow(e)
        end
    end
end

function parserow(schema, strings)
    function parse_handling_error(T, string, column)
        try parsefield(T, string)
        catch e
            if isa(e, ParseErrorLoc)
                e.column = column
            end
            rethrow(e)
        end
    end
    [parse_handling_error(T, string, column)
     for (column, (T, string)) in enumerate(zip(schema, strings))]
end

function parsefile(io, schema)
    line = 1
    while !eof(io)
        strings = split(chomp(readline(io)), ';')
        try parserow(schema, strings)
        catch e
            if isa(e, ParseErrorLoc)
                e.line = line
            end
            rethrow(e)
        end
        line += 1
    end
end

test_file = """
1;2;3
4;5;6
7;error;9
"""

parsefile(IOBuffer(test_file), fill(Int, 3))