Thanks everyone for the comments.

2010/9/9 Yusuke ENDOH <mame / tsg.ne.jp>

> Hi,
>
> 2010/9/9 Nikolai Weibull <now / bitwi.se>:
> > On Thu, Sep 9, 2010 at 07:00, Yukihiro Matsumoto <matz / ruby-lang.org>
> wrote:
> >> Hi,
> >>
> >> In message "Re: [ruby-core:32200] Ruby 2.0 Wish-list?"
> >>    on Thu, 9 Sep 2010 11:49:06 +0900, Rocky Bernstein <
> rockyb / rubyforge.org> writes:
> >>
> >> |Any plans for error messages in languages other than English?
> >>
> >> For application internationalization, you can use gettext, etc.
> >> But for Ruby itself, we have no plan, because:
> >>
> >>  * for most of Ruby code use English words, so that we can expect
> >>    programmers to recognize English messages.
> >>  * allowing message switch make the interpreter more complex, and
> >>    bloat.
> >
> >  * Localized error messages are a lot more difficult to Google
>
>  * it requires translation whenever new exception is introduced,
>   which may block release management.
>
>  * you can do it yourself if you really need it :-)
>
>
> $ cat japanese-error-message.rb
> # coding: UTF-8
>
> at_exit do
>  trace = $!.backtrace
>  msg = $!.to_s
>  msg = case msg
>  when /\Aundefined local variable or method `(.*?)' for (.*?)\z/
>    "#$2 には #$1 というローカル変数もメソッドも定義されていません"
>  # ...
>  else
>    msg
>  end
>  puts "#{ trace.shift }: #{ msg } (#{ $!.class })"
>  trace.each {|t| puts "        from " + t }
>  exit!
> end
>
>
> $ ./ruby -r./japanese-error-message -e 'def foo; bar; end; foo'
> -e:1:in `foo': main:Object には bar というローカル変数もメソッドも定義されていません (NameError)
>        from -e:1:in `<main>'
>
> --
> Yusuke Endoh <mame / tsg.ne.jp>
>
>