-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 03/30/2010 11:45 AM, Peter Dimov wrote:
Which is only a problem if you're doing something that produces a NaN. In XInt, that's rare, and all such cases are very carefully documented.
Right. What is the purpose of the NaN? Its function is to delay the exception until the first use of the result, making the point of the erroneous calculation harder to trace. In what scenario is this a good thing?
If you ignore NaN results from functions that return them, then yes, that is the result. If you use them properly, and check for NaN as soon as a function that can return it returns, you will know the exact line that it came from. In what scenario is this a bad thing?
(*) And by the way, out of memory is not overflow. It's possible to run out of memory while computing an integer that is smaller than another integer that already has been computed. This is not what overflow means.
If that was aimed at XInt, note its purpose: it's intended to allow calculation with numbers of arbitrary length, up to the memory size of the system. If the system can't provide enough memory for it at some point, that *is* an overflow -- the number is too large to represent.
No, it isn't an overflow. An overflow doesn't occur at random, depending on some external resource. Overflows are deterministic and depend on the fixed range of the number. A 32 bit signed integer always overflows at 2^31. If a calculation produces a number X without overflowing, that same calculation, when performed again, will still produce X without overflowing. This is not true for out of memory conditions. Arguing that making a copy of a number can overflow is stranger still.
I'm sorry you don't see the logic behind it. I do, and n1744 (the "standardese" for the large-integer library proposal) specifies it, on page two: "all integer operations which return an (temporary) integer and many member operators may fail due to insufficient memory. Such errors are reported as overflow_error exceptions (as available memory defines the range of the integer class)." As such, I'll need a much stronger reason than that to change it. - -- Chad Nelson Oak Circle Software, Inc. * * * -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkuyYKMACgkQp9x9jeZ9/wR1+gCePQwHET1YkVjsZ6O83WRnP4Ty 6TgAnA4kN0ghFxfzIBURGVCNR9KXF4xo =J5H+ -----END PGP SIGNATURE-----