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From: "Randy Brukardt" <>
Subject: Re: renaming as classwide type
Date: Tue, 26 Sep 2023 00:46:07 -0500	[thread overview]
Message-ID: <uetr67$2c95g$> (raw)

It's not needless; there is an implicit conversion on an assignment, and it 
only needs to work one way. When you rename a variable, the conversion has 
to work both ways. But that's problematic, since conversions often involve 
checks and we don't want checks popping up in unexpected places (both for 
implementation reasons and for readability reasons).

Also, renaming does not change the nominal subtype of an object, regardless 
of what subtype is given in the renames. Ada 2022 allows you to omit the 
type name altogether since it provides little value.


"Simon Belmont" <> wrote in message
On Thursday, September 21, 2023 at 5:03:06?PM UTC-4, G.B. wrote:
> O does not denote an object of a class-wide type,
> I think. However, P'Class (o) does, so that renaming
> that would make r be of its declared type P'Class.

That seems needlessly pedantic, considering that assignment is fine (o2 : 
P'Class := o) as well as assigning it to an intermediate pointer (po : 
access P'Class := o'Access; r : P'Class renames po.all) 

  reply	other threads:[~2023-09-26  5:46 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-21 19:29 renaming as classwide type Simon Belmont
2023-09-21 21:03 ` G.B.
2023-09-21 23:19   ` Simon Belmont
2023-09-26  5:46     ` Randy Brukardt [this message]
2023-09-22  9:31 ` Simon Wright
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