Hi Everyone, Below is my review of the proposed Boost.Exception library. * What is your evaluation of the design? I personally like that the exception library is implemented in just a couple of header files, without having to drag in a lot of other libraries. It is succinctly implemented, though I have some reservations about some design decisions: get_error_info(T const &) returns a pointer instead of a const copy of the actual error_info it gets. This can be a potential headache to deal with especially in examining the error_info associated with the thrown exception. A proposed change would be to have get_error_info(T const &) return a const copy of the data, while get_error_info_ptr(T const &) would return a pointer as in the current version. Although it might also take quite some effort to remove the runtime polymorphic behavior which relies on shared_ptr<>'s and virtual tables with info_base, perhaps an expression templates-based approach to building exceptions that derive from a common base could mitigate these (theoretical) inefficiencies introduced with runtime polymorphic behavior? A linear inheritance encapsulating the different information using something like Boost.Fusion's or Boost.MPL's `fold` concept to create an exception type using expression templates might work. Then I haven't tried this myself, so it might be worth considering in the future. My concern with the use of shared_ptr<>'s is that in cases where an exception pertaining to "out of memory" conditions would arise, throwing a boost::exception and then having to allocate more memory just to encapsulate additional information would lead to undesirable termination. So keeping exception data statically allocated on the stack instead of being in the heap might be a good alternative. This is just my thinking though I don't have enough data to back this up. * What is your evaluation of the implementation? It's very cleanly implemented, and very much readable. * What is your evaluation of the documentation? The documentation is very well written although an alternative example aside from the case with file IO would be greatly appreciated. That said, the example given is sufficient enough to make a case for the utility of the library. * What is your evaluation of the potential usefulness of the library? In cases where minimal memory footprints are required, the current implementation introduces a lot of unnecessary allocations on the heap when additional information is being encapsulated into the exception. An expression templates-based approach as described above (though untested) should be able to mitigate this consequence. In all other cases where efficiency and performance are not critical, I can see this exception library to be very useful. * Did you try to use the library? With what compiler? Did you have any problems? Not yet, though I see myself using this in a project really soon. * How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? I went into the implementation details, and the conceptual design based on the source code. I did a quick read of the documentation, which didn't seem to change since the first time this library has been introduced. * Are you knowledgeable about the problem domain? I have been writing ad-hoc exception hierarchies based on std::exception for quite a while already, and I can say that this implementation of exceptions is a welcome development. * Do you think the library should be accepted as a Boost library? Be sure to say this explicitly so that your other comments don't obscure your overall opinion. I think yes, it should be accepted as a Boost library. I can see it getting a lot of improvements in terms of implementation though, but being in the Boost C++ Library will allow more people to be able to propose changes and eventually extend this library in many different ways. -- Dean Michael C. Berris Software Engineer, Friendster, Inc. [http://cplusplus-soup.blogspot.com/] [mikhailberis@gmail.com] [+63 928 7291459] [+1 408 4049523]