excn_handle

# File lib/debug.rb, line 652
    def excn_handle(file, line, id, binding)
      if $!.class <= SystemExit
        set_trace_func nil
        exit
      end

      if @catch and ($!.class.ancestors.find { |e| e.to_s == @catch })
        stdout.printf "%s:%d: `%s' (%s)\n", file, line, $!, $!.class
        fs = @frames.size
        tb = caller(0)[-fs..-1]
        if tb
          for i in tb
            stdout.printf "\tfrom %s\n", i
          end
        end
        suspend_all
        debug_command(file, line, id, binding)
      end
    end