Ada

Accurate Ada News

Number 41 - April 1, 2018

The ARG, the keepers of the Ada Standard, have approved several new features for the Ada language. Among other features, there is a new assertion policy and a new pragma intended to improve the safety of Ada code.
While we find pragma Assure and procedure Unchecked_Reallocation interesting (and we have an interview with their primary author, Steve Baird, lined up for a future issue), we're most intrigued by the new assertion policy.
Building on the ideas pioneered in the Vigil programming language (https://github.com/munificent/vigil), the Blackhole assertion policy ensures that code that doesn't meet its specification is sent somewhere it cannot cause harm to the users of the program.
Randy Brukardt, Editor for the ARG, notes that new policy builds on the advantages of the existing policies. “Existing policies just signal an error when a subprogram or other contract is violated. This potentially could mean that the contract violation itself causes a safety violation. With Ada's emphasis on safe code, that's not good enough. The new policy avoids the safety violation by eliminating the problematic code from the program, so that it cannot cause future problems.”
We couldn't help but wonder why the new policy has the name it does. Mr. Brukardt explained that “we tried various names for this policy: 'Tar_Pit', 'Dumpster', and 'Congress' were some of the suggestions – we thought that 'Blackhole' best represented a place where something goes and never comes back.”
Technical details on the new policy can be found here on the ARG website.
The lead engineer for one major Ada vendor, speaking off the record, reports that they have implemented the new policy in their Ada compiler and is now beginning to use it in the implementation of their compiler technology. “The hardest part of our implementation was creating a singularity as needed. Having solved that, we expect that the Blackhole policy will cut the number of bugs delivered to customers by 90%, and reduce the technology support costs of our compiler to virtually nothing.”
At presstime, Accurate Ada News was unable to reach any of the beta testers of that that vendor for comment on the new assertion policy.
In other news from the same Ada vendor, their latest version has been delayed because of problems in testing. A source, not authorized to speak for the company, tells Accurate Ada News that the problem is related to communication with the testing team. “It's like they vanished from the face of earth!” according the source. We think this is just a yarn spun to cover for a product that isn't ready for the public.
More on this developing story in the next issue of Accurate Ada News.
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