Re: [Caml-list] Module/functor question

[ronniec95@lineone.net]

Thanks for that. It's all kind of starting to make sense now!!

I'll experiment a little more and hopefully should be able to get some buyin
at work for using Ocaml for our trading applications. Now the messaging
is working, along with XML transforms (thanks to all who helped). Just the
DB to do.....

Ronnie

>-- Original Message --
>Date: Mon, 15 Mar 2004 13:34:14 +0100
>From: Andreas Rossberg <rossberg@ps.uni-sb.de>
>To: ronniec95@lineone.net
>CC: caml-list@inria.fr
>Subject: Re: [Caml-list] Module/functor question
>
>
>ronniec95@lineone.net wrote:
>>
>> I've copied the exact code below since it's not that long. I wonder
>> about header.mli which has 'type t=u' in it which was the only way of
>> getting it all to fit together. Why do I have to do that?
>
>You don't have to, if you declare the types at the right places, i.e.
>inside the modules. Actually, you don't need the local modules at all,

>since compilation units are already modules. Here is the sketch of a
>simplified version (not tested).
>
>   (* header.mli *)
>   type t
>   val as_xml : t -> Xml.xml
>   val create : Xml.xml -> t
>   val make : ?version:int -> ?msgtypeid:int ->
>              string -> string -> string -> t
>
>   (* header.ml *)
>   type t = { version : int;
>              created : Calendar.t;
>              environment : string;
>              msgtypeid : int;
>              msgtype : string;
>              originatorid : string;
>              machineid: string; }
>   let as_xml d = ...
>   let create (root:Xml.xml) : t = ...
>   let make ?(version = 1) ?(msgtypeid=1) msgtype originator env = ...
>
>   (* main.ml *)
>   module type CONSTRUCTOR =
>   sig
>       type t
>       val as_xml : t -> Xml.xml
>       val create : Xml.xml -> t
>   end
>
>   module MessageSender (C : CONSTRUCTOR) =
>   struct
>       let send msg = print_string (Xml.to_string (C.as_xml msg))
>   end
>
>   let _ =
>       let module M = MessageSender(Header) in
>       M.send (Header.make "Header" "TestMessage" "DEV")
>
>--
>Andreas Rossberg, rossberg@ps.uni-sb.de
>
>Let's get rid of those possible thingies!  -- TB
>


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