[Ocaml-lib-devel] [ExtLib] Design of Enum.init ?

[David T. <Dav...@un...>]

   Hi,

 I'm currently reviewing my code before sending in a second contribution
(this time, a patch to Enum) and I'm a bit puzzled by Enum.init . With
current implementation, creating a clone of an enumeration created with
[Enum.init n f] is the same thing as calling [Enum.init n f] again. In
particular, if one is to iter through both enumerations, [f 0] will be
invoked both by the original and by the clone, [f 1] will be invoked
both by the original and by the clone, etc.

For instance
(*start of example*)
let print e = Enum.iter (Printf.printf "%i; ") e;;
let f x = Printf.printf "\n\t(Evaluating %i)\n" x; x;;
let test_1 = Enum.init 5 f;;
let test_2 = Enum.clone test_1;;

# print test_1;;
        (Evaluating 0)
0; 
        (Evaluating 1)
1; 
        (Evaluating 2)
2; 
        (Evaluating 3)
3; 
        (Evaluating 4)
4; 

# print test_2;;
        (Evaluating 0)
0; 
        (Evaluating 1)
1; 
        (Evaluating 2)
2; 
        (Evaluating 3)
3; 
        (Evaluating 4)
4; 
(*end of example*)

I find this strange and inconsistent with the cloning of enumerations
created with [from] or forced. Now, it's rather easy to fix this but I'm
wondering if this behaviour is a bug or by design.

Cheers,
 David

-- 
David Teller
 Security of Distributed Systems
  http://www.univ-orleans.fr/lifo/Members/David.Teller
 Angry researcher: French Universities need reforms, but the LRU act brings liquidations.