Re: Press Release - Ada 2012 Language Standard Approved by ISO

[Shark8 <onewingedshark@gmail.com>]

On Sunday, December 23, 2012 2:08:53 AM UTC-6, Dmitry A. Kazakov wrote:
> 
>  Contracted exceptions is an urgent need.

There are contracted exceptions, of a sort -- the LRM guarantees that the predefined relational operator will not raise an exception and the predefined operators on integers will only raise NUMERIC_ERROR ( http://archive.adaic.com/standards/83lrm/html/lrm-04-05.html ) -- of course that's an external contract.

The ability to have such guarantees applied to the programer's Ada text would indeed be a boon; perhaps using an aspect of the following form:
   Exceptions => [ NOT NULL | NULL | "EXCEPTION_NAME"[, OR "EXCEPTION_NAME"]]

Where EXCEPTION_NAME would map to either predefined exceptions or visible user-defined exceptions, NULL would assert that the procedure raises no exceptions, and NOT NULL would be what we have now (subprogram can raise any exception).

The problem with the above is that there's some exceptions which are dependent on the [executing] environment at Run-time (STORAGE_ERROR springs to mind).