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Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!iuvax!cica!tut.cis.ohio-state.edu!att!cbnewsl!arny
From: arny@cbnewsl.ATT.COM (arny.b.engelson)
Newsgroups: comp.lang.ada
Subject: Re: Questions on Ada...
Message-ID: <1067@cbnewsl.ATT.COM>
Date: 11 Jul 89 19:41:26 GMT
References: <3034@wpi.wpi.edu> <979@cbnewsl.ATT.COM> <4611@omepd.UUCP>
Reply-To: arny@cbnewsl.ATT.COM (arny.b.engelson)
Distribution: usa
Organization: AT&T Bell Laboratories
List-Id: <comp.lang.ada>

In article <4611@omepd.UUCP> vladimir@inteloc.UUCP (Vladimir G. Ivanovic) writes:
>In article <979@cbnewsl.ATT.COM> arny@cbnewsl.ATT.COM (arny.b.engelson) writes:
>>There is more than one way to do this.  One alternative is to use overlays.
>>Simply declare an integer array of the proper length, use an address clause
>>to overlay it at the location occupied by the structure you are copying
>>from, and copy it to an integer array overlaid at the destination address.
>>Another alternative is to use unchecked conversion from one type to another.
>>Again, the Ada purists will be up in arms (overlays are officially erroneous),
>>but the concept is very useful in some situations.

>I agree about the utility, but disagree about the "officially erroneous"
>comment attributed to Ada purists.  In fact, I'd say there are entire classes
>of problems that cannot be solved without using Unchecked_Conversion. 

Read my original posting more carefully.  I did not say that Unchecked_
Conversion was erroneous.  I said overlays are erroneous, and they do
not use U_C.  Read LRM 13.5:8.

  - Arny Engelson   att!wayback!arny