Re: [Ocaml-lib-devel] A proposal for Unicode character and UTF-8 modules.

[Nicolas C. <war...@fr...>]

> > I think that one of the thing that could be done is to merge the two
modules
> > into one
>
> I made UChar and UTF-8 two different modules because,
>
>   * Char and String are different modules, and I want to make unicode
>   modules similar to the string API of stdlib as far as possible, and
>
>   * Users, or eventually we, may provide other Unicode string (UTF-16,
>     UCS-4, BOCU, or whatever).  Making UTF-8 an independent module
>     would make changing Unicode string implementation easier.
>
> If nested modules are acceptable, we can pack them into one module, of
> course.

No it's ok this way :-)

> > work a little on function/type naming and better exception
> > handling.
>
> Is it better to define its own exception than to use invalid_arg?
> Currently, UTF-8 module don't do bound checking itself for the
> performance reason.  Is it better to do bound checking in UTF-8, and
> raise its own exception other than Invalid_arg?

Depends.
ExtLib exception policy is the following :
- if exception should be catched , then use a module-specific exception
- if exception is a programmer failure, then you can use invalid_arg or
failwith
Theses statement come from the fact that invalid_arg and failwith are
type-unsafe since you need to catch them with the good string in order to
have a correct catching behavior. Using module-specific exceptions, even
with a string parameter, reduce the number of bad-catchs.

In the case of parsing (xml , unicode, etc.) the data often comes from an
external source, and the programmer will most of the time want to handle
parsing failures , theses should then not be considered as "exceptions worth
catching" and declared as module-specific exceptions.

Nicolas Cannasse