Re: Allocation questions

["Randy Brukardt" <randy@rrsoftware.com>]

>"Adam Beneschan" <adam@irvine.com> wrote in message 
>news:336b285f-2245-4ede-8528-841a2c713e80@b7g2000pre.googlegroups.com...
>On May 28, 6:39 am, Martin <martin.do...@btopenworld.com> wrote:
>> > 2 more questions:
>>
>> > 1) In fact (due to my background!), I would like to use the dot 
>> > notation:
>> > object.method.
>> > So I have add "tagged":
>
>I'm not sure I'd recommend declaring a type "tagged" JUST to get the
>dot notation.  There's a small amount of overhead involved with making
>a type tagged; but more importantly, a fair number of language rules
>are different for tagged types than for untagged types.  (You ran into
>one different rule below; another one that comes to mind immediately
>is that there are differences in the semantics of "=".  There are
>others.  You might not run into any of them, though.)

That's strange advice, given that the mantra of the Ada 95 team was that 
"tagged types work right". Yes, there are minor differences in semantics, 
but in all cases that I know of, tagged types work more logically than 
untagged types (mainly because of compatibility issues). I'd be more likely 
to reverse the advice and suggest that you declare all of your records 
tagged. (Well, I'd go further and suggest that pretty much everything ought 
to be declared controlled, which of course subsumes tagged, but that isn't 
as clear cut.)

I can understand a concern about the overhead of a tag, but that only 
matters if there are going to be many of these objects and the objects are 
relatively small (given that tags are fairly small). Neither of those seems 
to be true in this case.

                                               Randy.