I'm NOT really pushing for this as a boost library -- View this message in context: http://boost.2283326.n4.nabble.com/safe-numerics-questioning-the-basic-idea-... Sent from the Boost - Dev mailing list archive at Nabble.com.

On Tue, Nov 18, 2014 at 7:57 PM, David Stone wrote:

This is an issue that is especially important to me, as I have written a library that also has the goal of making integer arithmetic safe: the bounded::integer library: http://doublewise.net/c++/bounded/ . I presented this library at C++Now 2014 this year. It has a different philosophy from the checked integer type that you described. It instead has compile-time min and max bounds on each integer type, and the goal is to replace all uses of built-in integer types. The result of the arithmetic operators is a new type that is able to hold any result of the operation (so bounded::integer<1, 10> + bounded::integer<4, 7> == bounded::integer<5, 17>).

Your implementation appears to also disable implicit conversions if the destination type is smaller. I abhore the C++ implicit conversion of integers, and I started to write an implementation that did only this (obviously I did not know about either of these libraries). Does anyone else find a library that only does a compile-time implicit conversion check useful? I know gcc and clang both have warnings that would do just this, but I also like the idea of having it consistent across any compiler. Might add too much overhead in compilation time for such a small feature. Also, what if one (or both) of these libraries added named ("add", "subtract", etc.) NOEXCEPT functions that returned bool? Overflow could be checked and handled without a try catch block. Lee

2014-11-18 19:45 GMT+01:00 Robert Ramey :

I'm NOT really pushing for this as a boost library

I am not sure I got your message right. Are you saying SafeNumerics library is there in the Incubator only to test the Incubator? I am still in the process of reviewing it. Does it mean it will be done for nothing? Regards, Andrzej

Andrzej Krzemienski wrote

2014-11-18 19:45 GMT+01:00 Robert Ramey <

ramey@

>:> I'm NOT really pushing for this as a boost library>I am not sure I got your message right.Are you saying SafeNumerics library is there in the Incubator only to testthe Incubator?

Hmmm - I didn't think about this aspect of it. I don't remember now why I originally wrote it. But when I needed an example for the incubator I used it because it's non-trivial in the issues it raises - there has already been lots of discussions on this topic. but usually not in terms of a real implementation. non-trivial in it's implementation - but not impossibly hard either. small enough to serve as an example that everyone can understand something that might have a wide enough interest to raise these kinds of questions. As far as submitting it to boost I've got my hands full just maintaining the serialization library and flogging the incubator. safe numerics opens up a huge amount of new territory to conquer: floating point modular arithmetic alternative type promotion policies to automatically promote types of results of avoid overflows entirely using safe_range to strict types so that they can never overflow - requires implementation of range arithmetic at compile time implementation of safe(type) where type is any numeric type as defined by (limits) So submission to boost would lead to this turning into a huge project for me if I were to do it. I actually did spend some time exploring the above extensions but failed to produce what I wanted. I would hope that one or more of the following might happen Someone might take responsibility for the library and submit it to boost - (note someone already suggested it as a candidate for the standard library!). Someone might decide to sponsor the library (in a monetary sense) which would justify the spending of more time on it. (How many billions of $ might this have shaved off the F-35 fighter jet program which is currently 7 years behind schedule?). It might just sit there garnering reviews and accumulating users. That is, once it's in the incubator, does it really need to be the official boost distribution (or the standard one) at all? Any one can git-clone or downloaded into their boost directory structure and start using it in exactly the same way that they use boost now. That is, for this person it IS a boost library. Could this be the future of boost - modular deployment like the incubator has. The incubator isn't there yet - but its headed in that direction. Maybe boost get's out of the deployment and distribution business and concentrates it's efforts on certification of library quality. In any/all of the above, you're review will be really useful. In fact more useful than a normal boost library review. Normally boost reviews are "lost" in the developer's list after the review ends. Reviews in the incubator be seen by anyone who looks at the safe numerics library page and is considering the library now or in the future. Robert Ramey -- View this message in context: http://boost.2283326.n4.nabble.com/safe-numerics-questioning-the-basic-idea-... Sent from the Boost - Dev mailing list archive at Nabble.com.

Andrzej Krzemienski wrote

One remark as to BLIncubator I have already is that I was really missing a preview button when formatting my comment. I never know in this WordPress whether safe <int> will be treated as a HTML tag, and other problems like this.

Good point - I'll look into this -- View this message in context: http://boost.2283326.n4.nabble.com/safe-numerics-questioning-the-basic-idea-... Sent from the Boost - Dev mailing list archive at Nabble.com.