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Newsgroups: comp.lang.ada
Date: Thu, 28 Jun 2018 05:08:37 -0700 (PDT)
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Subject: Re: Why are Ada compilers difficult to write ?
From: Vincent <vincent.diemunsch@gmail.com>
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Xref: reader02.eternal-september.org comp.lang.ada:53402
Date: 2018-06-28T05:08:37-07:00
List-Id: <comp.lang.ada>

Le lundi 25 juin 2018 22:07:16 UTC+2, Dirk Craeynest a =C3=A9crit=C2=A0:
>
> >> At Ada-Europe 2018, Maroua Maalej presented a paper with the title "Sa=
fe
> >> Dynamic Memory Management in Ada and SPARK".  It explains how you can
>
>=20
> Paper:
> https://link.springer.com/content/pdf/10.1007%2F978-3-319-92432-8_3.pdf

I am a little bit shocked by this proposal :

1. The "Owning Object Aspect" changes the semantics of Access types in Ada.=
=20
X :=3D Y; would now mean that=20
 - X'New =3D Y'Old
 - Y'New =3D null=20

2. Shouldn't we create a new category of Owning Types instead of a new spec=
ial case of access values ? And add a new operator like :
X <- Y;

3. In fact shouldn't this idea of owning object be instatiated in Ada as li=
mited types ? Wasn't the purpose of limited types to precisely forbid assig=
nement so as to avoid aliasing of dynamically allocated objects ? Like task=
s types for instance, or protected types...

Regards,

Vincent