]> Gaurav Chanda wrote: > class point = > object > value mutable x = 0; > method addunit v = v+1 ; > end; > > class type point = > object > value mutable x : int; > method addunit : int -> int ; > end; Are you sure this class does what you expect it to? Member variable x gets initialized to 0, cannot be set to anything else, nor can its value be fetched. Furthermore, method addunit could be redefined as a simple function: # let addunit x = x + 1;; BTW, please try to post correct code. You should have written class type point : object val mutable x : int method addunit : int -> int end class point = object val mutable x = 0 method addunit v = v + 1 end You have misunderstood the use of class interfaces. The point class which you define in point.ml *is not* the implementation of the interface point in point.mli. Also, module point, whose interface is defined in point.mli, does not export a class point, only *class interface* point. Here is how to separate class interfaces from class implementations. Copy the following in point.mli: > class type point_sig = > object > val mutable x : int > method addunit : int -> int > end > class point : point_sig Copy the following in point.ml: > class type point_sig = > object > val mutable x : int > method addunit : int -> int > end > class point : point_sig = > object > val mutable x = 0 > method addunit v = v+1 > end Alex ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners