* What is your evaluation of the design?
I'm not keen on the use of operator<< to add the data to the exceptions. << has two existing meanings, left-shift and formatted output. Note that the standard library does not use << for operations like push_back() and insert(). Adding another meaning here is not helpful. For example, it's common for exceptions to have human-readable formatted content. A user seeing code that uses operator<< on an exception might easily imagine that this is doing formatted output, and think "cool! I can do formatted output to this exception!", and write: catch (some_exception& E) { E << " while frobinacting at warp level " << warp_level; throw; } Of course this isn't going to work. If your code used a more conventional syntax, e.g. E.add_info<errno_tag>(errno); then this confusion would be avoided. (And I think it could be more concise too.) Is "exception" the best choice of name for this library? The name boost::exception might give the impression that it's the base class for all Boost exceptions, which is not the case; I might accidentlally write catch (boost::exception& E) { cerr << "got an exception from Boost: ....."; Also, there's the possibility that someone might propose some other exception-related library, orthogonal to this one, in the future. How about "tagged_exception"?
* What is your evaluation of the implementation?
I haven't looked at the code.
* What is your evaluation of the documentation?
Good. You might like to say something about the overhead that is added, i.e. that there is a std::list<something> in each exception (or whatever). (Remember that there are still plenty of people who dislike exceptions because of the perceived overhead that they involve.) I think you do say something about the exception guarantee, but it might be useful to add a more explicit section near the start describing the exception guarantee and also whether any dynamic memory allocation is involved; what happens if the exception that was thrown was "out of memory"?
* Did you try to use the library? With what compiler?
No.
* How much effort did you put into your evaluation?
About an hour reading the docs and preparing this message.
* Are you knowledgeable about the problem domain?
I have previously considered the problem of storing errno and a filename in an exception and have my own non-generic solution.
* Do you think the library should be accepted as a Boost library?
Only if operator<< is replaced. Regards, Phil.