class Byebug::TraceCommand

def execute
  if @match[1] =~ /on|off/
    onoff = 'on' == @match[1]
    #if @match[2]
      Byebug.tracing = onoff
      print "Tracing is #{onoff ? 'on' : 'off'}\n"
    #else
    #  Byebug.current_context.tracing = onoff
    #  print "Tracing #{onoff ? 'on' : 'off'} on current thread.\n"
    #end
  elsif @match[1] =~ /var(?:iable)?/
    varname=@match[2]
    if debug_eval("defined?(#{varname})")
      if @match[3] && @match[3] !~ /(:?no)?stop/
        errmsg "expecting \"stop\" or \"nostop\"; got \"#{@match[3]}\"\n"
      else
        dbg_cmd = (@match[3] && (@match[3] !~ /nostop/)) ? 'byebug' : ''
      end
      eval("trace_var(:#{varname}) do |val|
              print \"traced variable \#{varname} has value \#{val}\n\"
              #{dbg_cmd}
            end")
    else
      errmsg "#{varname} is not a global variable.\n"
    end
  else
    errmsg "expecting \"on\", \"off\", \"var\" or \"variable\"; got: " \
           "\"#{@match[1]}\"\n"
  end
end