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From: Robert A Duff <bobduff@shell01.TheWorld.com>
Newsgroups: comp.lang.ada
Subject: Re: a new language, designed for safety !
Date: Sun, 08 Jun 2014 09:56:56 -0400
Organization: The World Public Access UNIX, Brookline, MA
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Date: 2014-06-08T09:56:56-04:00
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Georg Bauhaus <rm-host.bauhaus@maps.futureapps.de> writes:

> - "I can view this Obj as of type TA and call Op"
>     (Ada, wrong view)
>
> - "I can send Op: to Obj of presumed type TA"
>    (Objective-C, no method)

The two errors seem rather different, to me.  To get the Ada error, you
have to do a downward type conversion, something that is well known to
be questionable -- you need to be careful to say "if X in T3'Class...".

The dangling dispatch error in Objective C can happen on any call,
and there's no practical way to protect against it.

- Bob