properties fo objects

[r3d9u11]

Hi, I need a help with properties. Why setter isn't call? Also how to set 
property "title" to readonly state (disable setter)? 
    
    
    type
      Info* = ref object of RootObj
        level: int
        title: string
    
    proc `level=`*(info: var Info, level: int) {.inline.} =
      info.level = level
      info.title = "Level " & $(level)
    
    var info: Info
    new info
    
    info.level = 5
    
    echo info.title