Re: private type discriminants ignored?

["Samuel T. Harris" <sam_harris@hso.link.com>]

Robert A Duff wrote:
> 
> In article <35468F93.C371940@hso.link.com>,
> Samuel T. Harris <sam_harris@hso.link.com> wrote:
> >To one-up the pedantic theme :) Bob's "... unconstrained variable"
> >appears several lines after "a default means that the discriminant
> >can change". Perhaps I should have said "Not entirely complete."
> 
> :-)
> 
> Actually, what I *should* have said was, "The mere presence of a
> defaulted discrim (in the type decl) means that it is possible to create
> unconstrained variables of the type; the discriminants of such variables
> can change (but only by whole-record assignment)."

<-snip lots of good stuff ->

> >The subtle differences are lost on many of our (my company's)
> >Ada initiates and I have spent some time explaining the nuances
> >of this construction, especially as applied to polymorphic variant
> >records.
> 
> I would blame that on non-intuitive language rules.  Not on the poor
> programmers, who reasonably, but incorrectly, think that default
> expressions are for giving default values to discriminants.

Just so. These initiates are simply new to Ada, not poor programmers.

> 
> - Bob
> 

-- 
Samuel T. Harris, Principal Engineer
Raytheon Training Incorporated
"If you can make it, We can fake it!"