gistfile1

def expression_backtrace(backtrace)
  new_trace = []
  backtrace.each do |line|
    match = /(.*):([0-9]+):in/.match line
    file, linenum = match[1], match[2].to_i

    new_trace << line

    if File.exist?(file)
      expr = File.readlines(file)[linenum - 1]
      expr.strip!

      new_trace << "\tat expression: \"#{expr}\""
    end
  end

  new_trace
end

def foo
  raise # raise an error
end

def bar
  foo # call foo in bar
end

def baz
  bar # call bar in baz
end

begin
  baz
rescue => e
  puts expression_backtrace(e.backtrace)
end