Dear all,
    I have a question about val in class type, is it only useful in inheritance?
    for example
   
    class type text = object val mutable text : string end      
   
    let f (x : text ) = x#text;;                                                                                                                                                               
                      ^                                                                                                                                                                      
Error: This expression has type text                                                                                                                                                         
       It has no method text   
    Thanks -- Hongbo