例外を整形する

すでに別の関数が用意されていそうな気もする。

def format_exception(e)
  backtrace = e.backtrace
  head = "#{backtrace.first}: #{e.message} (#{e.class})"
  rest = backtrace.slice(1..-1).map {|i| "\tfrom #{i}" }
  ([head] + rest).join($/)
end

def foo
  raise 'xxxxx'
end

def bar
  foo
end

begin
  foo
rescue => e
  puts format_exception(e)
  raise e
end

C:/eclipse/workspace/rails_async_callback_runner/vendor/plugins/foo.rb:9:in `foo': xxxxx (RuntimeError)

	from C:/eclipse/workspace/rails_async_callback_runner/vendor/plugins/foo.rb:17

C:/eclipse/workspace/rails_async_callback_runner/vendor/plugins/foo.rb:9:in `foo': xxxxx (RuntimeError)

	from C:/eclipse/workspace/rails_async_callback_runner/vendor/plugins/foo.rb:17