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From: john@nospam.demon.co.uk (John McCabe)
Newsgroups: comp.lang.ada
Subject: Re: Variant Record Component
Date: Mon, 03 Mar 2003 09:24:54 GMT
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On Fri, 28 Feb 2003 16:15:52 GMT, John Harbaugh
<john.s.harbaugh2@boeing.com> wrote:

>Here's the situation:  I'm using a variant record to represent a Link 16
>(JTIDS) J7.6 message for memory-mapped I/O.  So a message comes in and,
>based on the message header, a particular structure is frozen.  Now I
>pass the message object to a decode function that is looking for
>particular message fields.  Well, surprise surprise, we occasionally
>raise Constraint_Error because the field in question is not present.

Areyou sure Constraint_Error is being raised because the field is not
present?

Are you checking the validity bits in the JTIDS message? Obviously if
the validity bits identify a field as being not supplied, trying to
process that field may result in a Constraint_Error if the data is out
of range. 

Best Regards
John McCabe

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