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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: How to get Ada to ?cross the chasm??
Date: Mon, 7 May 2018 15:40:04 -0500
Organization: JSA Research & Innovation
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Xref: reader02.eternal-september.org comp.lang.ada:52072
Date: 2018-05-07T15:40:04-05:00
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"Simon Wright" <simon@pushface.org> wrote in message 
news:lyfu36zh6w.fsf@pushface.org...
> "Randy Brukardt" <randy@rrsoftware.com> writes:
>
>> Yes. There's an issue with vector cursors, they can become invalid
>> because of "sliding" -- but vector cursors are rarely used (since the
>> entire point of the container is to allow indexing, it's usually
>> accessed that way).
>
> Thanks.
>
> I suppose one could include a 'generation' value in the vector,
> incremented every time an element is removed or added, copied to a
> cursor on creation of the cursor, and checked when the cursor is used. A
> lot of work, for a slight amount of gain.

Janus/Ada does (will do) something like that to detect almost all 
dangling/mispointed cursors, but it doesn't have to be quite that intensive.

                       Randy.