Re: [boost] Infinite precision integer draft
Gerhard Wesp Sent:
On Thu, May 25, 2006 at 04:41:32PM +0200, Maarten Kronenburg wrote:
Users can implement an unsigned_integer by deriving from integer, but this will not give any performance gain.
This would violate Item 32 in Effective C++, 3rd ed. by Scott Meyers: Make sure public inheritance models "is-a".
I agree it's not a good idea.
I suggest deriving from integer be disallowed in the TR2 proposal.
... however I don't think that is. If C++ had "final", then it could be compile time checked. As it is, I don't think TR2 could do more than make it undefined behaviour. We really don't want more undefined behaviour in C++ if we can avoid it. What is more, deriving from integer would actually work on all implementations (as far as public inheritance which doesn't model "is-a" works). -- Martin Bonner Martin.Bonner@Pitechnology.com Pi Technology, Milton Hall, Ely Road, Milton, Cambridge, CB4 6WZ, ENGLAND Tel: +44 (0)1223 203894
Martin, See my reply to Gerhard. Regards, Maarten. "Martin Bonner" <martin.bonner@pitechnology.com> wrote in message news:D997BF79D1E92C4793B7FCC04B4F90A555D1A0@pigeon.pi.local...
Gerhard Wesp Sent:
On Thu, May 25, 2006 at 04:41:32PM +0200, Maarten Kronenburg wrote:
Users can implement an unsigned_integer by deriving from integer, but this will not give any performance gain.
This would violate Item 32 in Effective C++, 3rd ed. by Scott Meyers: Make sure public inheritance models "is-a".
I agree it's not a good idea.
I suggest deriving from integer be disallowed in the TR2 proposal.
... however I don't think that is. If C++ had "final", then it could be compile time checked. As it is, I don't think TR2 could do more than make it undefined behaviour. We really don't want more undefined behaviour in C++ if we can avoid it. What is more, deriving from integer would actually work on all implementations (as far as public inheritance which doesn't model "is-a" works).
-- Martin Bonner Martin.Bonner@Pitechnology.com Pi Technology, Milton Hall, Ely Road, Milton, Cambridge, CB4 6WZ, ENGLAND Tel: +44 (0)1223 203894 _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
participants (2)
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Maarten Kronenburg -
Martin Bonner