[Ocaml-lib-devel] Exceptions

[skaller <sk...@us...>]

On Tue, 2004-08-31 at 05:26, Bardur Arantsson wrote:

> It seems there is no function to read exactly n characters
> into a string (ie. IO.nread just without automatically
> shortening the string if EOF is hit while reading). Since
> at least one person needs it (me :)) I thought I would add
> this:
> 
>    let really_nread i n =
>         if n < 0 then raise (Invalid_argument "IO.really_nread");
>         if n = 0 then


Seeing the exception being raised here suggests to
me Ocaml needs a better mechanism for errors.

The exception being raised conforms to the "Same way as 
Ocaml std lib" policy.

It exhibits these problems:

(1) It doesn't say which argument
(2) It doesn't say what the problem was
(3) There's no reference to the file/line position of the raise

>This will cause an infinite loop on non-blocking IO (r = 0).
>You might want to raise Sys_blocked_io in this case.

Weird. You raise Sys_blocked_io when in fact the problem
is that it *isn't* blocked??


-- 
John Skaller, mailto:sk...@us...
voice: 061-2-9660-0850, 
snail: PO BOX 401 Glebe NSW 2037 Australia
Checkout the Felix programming language http://felix.sf.net