Re: Exception types?

[Mats Weber <Mats.Weber@elca-matrix.ch>]

Brian Rogoff wrote:

> It isn't really a workaround, as you haven't really parameterized the
> package by an exception, and you can't pass that package as a generic
> formal package parameter. Mats workaround involved passing a success/failure
> function (an exception "wrapper"), which is a little better in the
> particular case I'm interested in.

This is not true, or at least inaccurate (I don't know what you mean by "a
success/failure function" or an exception "wrapper").

My proposal is to add parameters to exceptions, as in Modula-3 (and in Ada 95,
with the IMO ridiculous limitation to strings of 200 characters).

In one of the 9X Mapping documents, there was an extension to Ada's exceptions
that essentially made them part of the type system and you could derive them
much as you can derive types, thus creating a hierarchy of exceptions.

> [...] but I was wondering what the thinking was
> behind not having typed exceptions to begin with in Ada 83. I imagine the
> reason for not having them in Ada 95 could be upward compatibility.

The proposal was in the mapping, but was removed. Maybe someone who
participated actively in the language design can tell us why ?