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Subject: Re: Performance of records with variant parts
From: John Perry <john.perry@usm.edu>
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Xref: reader02.eternal-september.org comp.lang.ada:61729
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On Thursday, April 1, 2021 at 8:38:49 AM UTC-5, Niklas Holsti wrote:
> I assume by "X is variant" you mean that X has a variant_part (RM 3.8.1(2=
)).=20
>=20
> If the discriminant of Thing_Type has a default value, Intersection_Type=
=20
> can have a Thing_Type component without supplying it with a discriminant=
=20
> value, and Intersection_Type need not have discriminants nor a variant pa=
rt.

You're right. Originally Thing_Type didn't have a default value. Later I ad=
ded one, but I didn't think to change Intersection_Type.

Either way, the discriminant on Intersection_Type was the problem. Once I m=
odify Intersection_Type so that it is no longer variant, Intersections can =
return an Intersection_Type that contains a Thing_Type without the performa=
nce hit it had when Intersection_Type was variant.