behaviour of read_exdr/2 and write_exdr/2 with big (>32 bit) inte gers

From: josh singer <josh.singer_at_parc-technologies.com>
Date: Mon 21 May 2001 05:26:07 PM GMT
Message-ID: <0B9686DD2E83D411B67200508B9A9DA220A692@LON-SRV2>
The following happened on the Linux build of last Friday. I've had the
same problems with the Windows build.

[eclipse 1]: open(queue(""), update, q, []).

Yes (0.00s cpu)
[eclipse 2]:  read_exdr(q, R).

No (0.00s cpu)
[eclipse 3]:  flush(q). 

Yes (0.00s cpu)
[eclipse 4]: read_exdr(q, R).

No (0.00s cpu)
[eclipse 5]: write_exdr(q, 2147483648), flush(q).

No (0.00s cpu)
[eclipse 6]: read_exdr(q, R).

R = R
Yes (0.00s cpu)

The penultimate goal fails because the number is too big to represent in
32 bits. The inability to write a 64 bit integer in EXDR is documented
in the documentation of write_exdr/2. It is not clear from the
documentation that read_exdr/2 cannot read 64-bit integers. Presumably
the last goal should just fail. 

Incidentally, it seems anomalous that the representation of 64-bit
integers is documented in the EXDR format chapter of the
embedding+interfacing manual when Eclipse can't read or write them.
Perhaps either write_exdr and read_exdr should be updated to support
them, or this section of the documentation should be taken out.

josh

Developer, Parc Technologies Limited
josh.singer@parc-technologies.com
http://www.parc-technologies.com

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Received on Mon May 21 18:26:45 2001

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