Re: Ada Distilled by Richard Riehle

["Dan'l Miller" <optikos@verizon.net>]

On Saturday, July 28, 2018 at 10:41:53 AM UTC-5, Dmitry A. Kazakov wrote:
> On 2018-07-28 17:01, Dan'l Miller wrote:
> > Btw, because T2 is an extended tagged T1 and because S2 is an extended tagged S1, I think an alternate syntax would be expressive and useful for this special case as well instead of the explicitly-itemized same-named variants above.  Note however that (just like in PL/I GENERIC) union can confederate any types, not merely tagged types and not merely tagged-type extensions in a 'Class tree.
> > 
> >      type UT is union (T1'Class);     -- a blend of Algol68 UNION and Ada95 'Class
> >      type US is union (S1'Class);     -- a blend of Algol68 UNION and Ada95 'Class
> 
> That does not make sense because T1'Class is a singular type. For the 
> set of types rooted in T1 there is no name in Ada, since it does not 
> have types of types.

Well, Dmitry, you had better get busy correcting all the factually-incorrect Ada reference material out there an planet Earth, letting them know the error of their ways.  Here are some places to start your correction campaign of lots of emails to write and lots of telephone calls to make:

https://en.wikibooks.org/wiki/Ada_Programming/Object_Orientation#Terminology
“Class (of types) [plural] : a tree [!] of classes, rooted by a base class and including all the (recursively-)derived classes of that base class”

http://adapower.com/index.php?Command=Class&ClassID=FAQ&CID=352
“class is a set [!] of types [plural!] with similar values and operations; in particular, ••a type and and all [!] of its derivatives [!], direct and indirect••, represents a (derivation) class.”