Re: Syntax for tagged record types (was Re: Not intended for use in medical,)

[jsa@alexandria (Jon S Anthony)]

In article <mheaney-ya023680002005972314260001@news.ni.net> mheaney@ni.net (Matthew Heaney) writes:

> What would be really cool is to have the compiler treat a selector
> "invokation" that same as if it were a reference to a record component. 
> That way I could say
> 
> The_Stack.Top := 5;

This is similar to the issue of allowing function results to be
L-values.  I'm not entirely sure why this was considered a "bad" thing
(there's been many occasions I've seen where this would be nice).  At
the moment it is prevented for at least the reason that function
results are considered to be _constant_ objects.


> While we're at it, maybe we can throw in real constructors, too.  We can
> solve the "problem" with limited types,  by allowing a constructor to be
> called in the declarative region.  That way limited types wouldn't have to
> be definate, or go on the heap unnecessarily.

That's more or less what Limited_Controlled gives you.  You can "pass
parameters" to Initialize via discriminants.  You can also play the
"rename the function result" game for limited types (which I think is
actually pretty nice) and that does what you want as well.

/Jon
-- 
Jon Anthony
Organon Motives, Inc.
Belmont, MA 02178
617.484.3383
jsa@organon.com