On Fri, May 25, 2012 at 7:16 PM, David Rajchenbach-Teller < dtel...@mozilla.com> wrote:
> On Fri May 25 18:01:25 2012, Patrick Walton wrote: > > On 05/25/2012 08:43 AM, Kevin Cantu wrote: > >> This conversation reminds me of Alexandrescu's talk about D's scope > >> keyword: > >> > http://channel9.msdn.com/Events/Lang-NEXT/Lang-NEXT-2012/Three-Unlikely-Successful-Features-of-D > >> > >> > >> It looks like a graceful syntax for handling all sorts of nested error > >> and failure cleanup... > > > > I like the scope keyword, FWIW. It'd be even better if you didn't have > > to provide a variable name if all you want to do is execute some code > > at the end of the block. > > > > This would provide a facility like Go's "defer" keyword, but more > > general since it also admits C++ RAII patterns. > > > > Patrick > > What's the difference between |scope| and Rust's resources, exactly? > > Cheers, > David > > -- > David Rajchenbach-Teller, PhD > Performance Team, Mozilla > > > Regarding adding logs to the errors: - Boost.Exception has something similar: you can add class instances to the exception using the error info mechanism [1] - It also reminds me of what happens in case of failures using the "note" expressions, I believe the same notes could be reused in case of exceptions/errors to provide additional logs. Of course, there is a difference between the two schemes. Boost's is somewhat more powerful because it does not consist of adding simple strings but full-blown objects (which could be conditionned to be printable), and thus allow inspection of structured data at the error-handling site. It may be thought of as overkill too... Regarding D's scope keyword [2] There are several statements based on it: - scope(exit) xxxx where xxxx is executed on exit, no matter what - scope(failure) xxxx where xxxx is executed on exit if the previous statement failed - scope(success) xxxx where xxxx is executed on exit if the previous statement succeeded On the other hand, it kind of look like a hack, maybe it is an issue of getting used to it though. [1]: http://www.boost.org/doc/libs/1_49_0/libs/exception/doc/error_info.html [2]: http://dlang.org/exception-safe.html
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