Re: Calling inherited primitive operations in Ada

[Emmanuel Briot <briot.emmanuel@gmail.com>]

> As presented, this seems very over complicated. Elements and Definite_Elements 
> add no value, and this is just a complex way of writing 

I did point you to the full repository if you prefer an extensive, real-life code sample. This was just an extract showing the gist of the issue.

> One hopes that the actual library makes better use of these pkgs than this small 
> example.

One can check the full code and extensive documentation on the design in the github repository.
This is called code reuse, was invented quite a while ago.
These packages are mostly implementation details. They are used to build high-level packages similar to the Ada containers, except with much better code reuse, more efficient, and SPARK-provable.

> Ada has excellent features for hiding, but these are not among them. Assuming 

And that's exactly our point in this discussion. Ada on the whole is very good (we would not be using it otherwise), but it does have a number of limitations which are sometimes a pain, this being one of them. Not acknowledging the limitations when they exist is naive, all languages have them.

> that pkg Keys serves some actual role in the spec of Maps, then someone wanting 
> to use pkg Maps will need to understand that role, which involves understanding 
> Definite_Elements, which involves understanding pkg Traits, which involves 
> understanding Elements. 

which involves understanding Ada, which involves understanding the compiler, which involves understanding the kernel sources, ...
How many times have you checked the whole sources of the GNAT runtime to understand how they implemented the Ada containers ?

Emmanuel