From: Bob Duff <bobduff@theworld.com>
Subject: Re: Declaring constants for a abstract tagged type and concrete sub classes
Date: Mon, 06 Jul 2015 13:02:06 -0400
Date: 2015-07-06T13:02:06-04:00 [thread overview]
Message-ID: <87lhetb4oh.fsf@theworld.com> (raw)
In-Reply-To: 66fa1189-9c51-4290-be53-6f3c40545ce7@googlegroups.com
Serge Robyns <serge.robyns@gmail.com> writes:
> type T_Root ...
> No_Root_Element : T_Root := (a, b, c);
>
> type T_Sub is new T_Root ....
> No_Sub_Element : T_Sub := ( ??? No_Root_Element ???, x, y z);
One possibility is to declare T_Root with default values for the
components, such that those defaults are what you want for a "No_...".
Then you can do:
No_Sub_Element : T_Sub := (T_Root with X => X, Y => Y, Z => Z);
Or if T_Sub also has meaningful defaults, then:
No_Sub_Element : T_Sub := (T_Root with others => <>);
I don't much like using default values, but in this kind of case
it might be the best choice.
- Bob
next prev parent reply other threads:[~2015-07-06 17:02 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-06 10:10 Declaring constants for a abstract tagged type and concrete sub classes Serge Robyns
2015-07-06 11:55 ` G.B.
2015-07-06 13:49 ` Serge Robyns
2015-07-06 17:36 ` G.B.
2015-07-07 16:27 ` Serge Robyns
2015-07-07 17:21 ` G.B.
2015-07-07 19:51 ` Serge Robyns
2015-07-07 20:14 ` Simon Wright
2015-07-07 20:18 ` Jeffrey R. Carter
2015-07-06 15:42 ` Simon Wright
2015-07-06 16:35 ` Serge Robyns
2015-07-06 17:02 ` Bob Duff [this message]
2015-07-06 21:16 ` Serge Robyns
2015-07-06 17:30 ` gautier_niouzes
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