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Invitation to connect on LinkedIn
by Gautam Sewani via LinkedIn 04 Aug '11

04 Aug '11

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Re: [boost] [log] how to set attributes under multi-threaded application
by Sean Chittenden 04 Aug '11

04 Aug '11

>> In boost::log documentation, there's some code as following: >> >> * typedef attrs::mutable_constant< int> int_constant_t; >> boost::shared_ptr< int_constant_t> attr(new int_constant_t(-5)); >> lg.add_attribute("MyInteger", attr); >> BOOST_LOG(lg)<< "This record has MyInteger == -5"; >> >> **// Change the attribute value >> attr->set_value(100); >> BOOST_LOG(lg)<< "This record has MyInteger == 100"; >> * >> Now I have a situation in my multi-threading app: >> the 'attr->set_value()' could be called in different threads, so the >> following 'BOOST_LOG(lg)...' could access wrong attributes that is set by >> another thread. If I use a mutex to protect this, it would be stupid, >> because the log line might be filtered out, that means the 'locking mutex' >> is not neccessary. > > If thread synchronizaion is what bothers you, mutable constant has > internal locking ability, you can specify mutex and lock types in the > mutable_constant template parameters. You can find an example in the docs: > > <http://boost-log.sourceforge.net/libs/log/doc/html/log/detailed/attributes.…> > > So, when internal locking is used, you don't have to externally > synchronize access to this attribute, neither when you update its value > nor when you write log records involving it. > > > On the other hand, if you simply try to tag a specific log record with > an attribute (e.g. you want to make sure that a particular record has > MyInteger value -5 attached) then thread-specific attributes would be a > better option. You can add a scoped thread-specific attribute for this > record, this will not affect log records generated by other threads and > will not require any synchronization either. You can read more about > scoped attributes here: > > <http://boost-log.sourceforge.net/libs/log/doc/html/log/detailed/utilities.h…> This is a general comment about the documentation across the boost project and isn't entirely specific to the boost-log project, but wisdom such as this "the application of XYZ feature is ideally suited for the situation ABC" doesn't exist frequently in much of the boost documentation. I don't know if it's in some style guideline someplace, but having been a boost user for ~5yrs now and having forced boost on other developers for a few years now, this is one of the things that I acutely notice/get push back on regarding the boost project (especially when referencing its documentation). I actually just made this comment to Boris, the author of the "Boost Libraries" that one of the things that I like about his book is it actually distills practical examples because the boost docs are more geared toward other Boost developers vs consumers of the libraries. The biggest piece of feedback I get is summed up as, "Boost is high quality, but it requires a high degree of skill to apply. A lot of this is because the docs are frequently very dense and assume equivalent levels of STL competency to decipher what's written. Nine times out of ten, I don't need to customize boost or extend it, I just need to use it and there isn't something that I can easily reference and get what I'm looking for within 15-30min." And I'll admit, it took a good year of hammering away at examples and stubbing out little bits of code here and there before I became familiar and comfortable with implementing boost. Call it a byproduct of the PHP-ization of developers, I dunno, but I think there's a nugget of truth to be had in there (maybe add a quickbook type called "Implementors" with tips/hints? *shrug*). Anyway, Andrey, it'd be keen if you could include a note along these lines in the docs. Maybe a quickbook type for "Implementors." Cheers. -sc -- Sean Chittenden sean(a)chittenden.org

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[trac] trac/boost/browser/ no longer available?
by joaquin＠tid.es 04 Aug '11

04 Aug '11

Say I'm having a look at some changeset such as: https://svn.boost.org/trac/boost/changeset/73525 The names of modified files are displayed with a link to a full-code browsing page, for instance: https://svn.boost.org/trac/boost/browser/sandbox/variadic_macro_data/boost/… yet this page fails with No handler matched request to /browser/sandbox/variadic_macro_data/boost/variadic_macro_data/vmd.hpp I think this trac/boost/browser has been missing for some months now. I seem to remeber there was a link to it also from the trac home page, now also missing. Any clue about this? Thank you, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo Este mensaje se dirige exclusivamente a su destinatario. Puede consultar nuestra política de envío y recepción de correo electrónico en el enlace situado más abajo. This message is intended exclusively for its addressee. We only send and receive email on the basis of the terms set out at. http://www.tid.es/ES/PAGINAS/disclaimer.aspx

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[network] Bagged, Tagged, New Release 0.9.1
by Dean Michael Berris 04 Aug '11

04 Aug '11

Good day everyone! If you're not interested in cpp-netlib's progress, please stop reading now. :) I'm happy to announce that cpp-netlib (the library that's hoping to be Boost.Network someday) is now available for general availability. You can get the latest from https://github.com/cpp-netlib/cpp-netlib/downloads and find out what's new at http://cpp-netlib.github.com/0.9.1/whats_new.html . This is an updated release that's inching closer to the "1.0" release that's going to be up for review. I've also written a more detail-filled announcement that you can read over at http://cplusplus-soup.com/2011/08/04/cpp-netlib-0-9-1-released/ -- please feel free to comment and share as you see fit. I'm looking to work with Michael Caisse who has agreed to be the review manager for Boost.Network to hopefully have a review at a convenient time for both of us. Right now I'm gunning for Q4 of 2011, but that's still fairly a ways away so things may still change. Cheers everyone, I do hope this helps! -- Dean Michael Berris http://about.me/deanberris

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numeric_cast
by Brandon Kohn 03 Aug '11

03 Aug '11

Hello, Recently I was creating a new numeric type which I wanted to use along with boost::numeric_cast. I read over the docs and examples and found that it seemed to support (at least partially) the notion of policy driven casting operations. I was unable to figure out how one might use a custom conversion or overflow policy along with the actual boost::numeric_cast<N>(x) function. In the end I created a workaround which seemed to work nicely: template <typename ConversionTraits, typename EnableIf = void> struct numeric_cast_traits { typedef def_overflow_handler overflow_handler; typedef UseInternalRangeChecker range_checker; typedef Trunc < typename ConversionTraits::source_type > rounding_policy; }; template <typename Target, typename Source> inline Target numeric_cast( Source arg ) { typedef boost::numeric::conversion_traits<Target, Source> conv_traits; typedef numeric_cast_traits< conv_traits > cast_traits; typedef boost::numeric::converter < Target , Source , conv_traits , typename cast_traits::overflow_handler , typename cast_traits::rounding_policy , boost::numeric::raw_converter< conv_traits > , typename cast_traits::range_checker > converter; return converter()(arg); } This change allowed me to easily customize the numeric_cast function for individual conversion types. Did I miss something in the official library? If not, would this change be something good to go in? Regards, Brandon Kohn

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[log] how to set attributes under multi-threaded application
by Jinqiang Zhang 03 Aug '11

03 Aug '11

In boost::log documentation, there's some code as following: * typedef attrs::mutable_constant< int > int_constant_t; boost::shared_ptr< int_constant_t > attr(new int_constant_t(-5)); lg.add_attribute("MyInteger", attr); BOOST_LOG(lg) << "This record has MyInteger == -5"; **// Change the attribute value attr->set_value(100); BOOST_LOG(lg) << "This record has MyInteger == 100"; * Now I have a situation in my multi-threading app: the 'attr->set_value()' could be called in different threads, so the following 'BOOST_LOG(lg)...' could access wrong attributes that is set by another thread. If I use a mutex to protect this, it would be stupid, because the log line might be filtered out, that means the 'locking mutex' is not neccessary. Who can help ? Jinqiang *btw, the boost::log documentation isn't too good, when I read it, I felt I lost in a juggle.*

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Move on Sandia intel
by Ion Gaztañaga 03 Aug '11

03 Aug '11

Hi, A test is failing for Move in Sandia-darwin-intel-11.1 (and 12.0): http://www.boost.org/development/tests/release/developer/output/Sandia-darw… and I don't know why, since Intel 11.0 in windows seems to work fine. Anyone with access to that compiler can help me? Thanks! Ion

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Boost.Process progress
by Boris Schaeling 03 Aug '11

03 Aug '11

There haven't been much news on Boost.Process lately which doesn't mean though that nothing is happening. I've been working on a Boost.Asio extension which can be used to wait asynchronously for Windows processes - see https://github.com/BorisSchaeling/asio. This was already supported by Boost.Process 0.4 but the implementation was heavily criticized. The code has been moved now to Boost.Asio (or at least I hope it will - I'm in contact with Chris :) and provides a new Windows I/O object called object_handle. The implementation is now based on the Windows function RegisterWaitForSingleObject(). The new I/O object can not only be used to wait for processes. It can also be used to wait for events, mutexes, semaphores etc. As it's not process-related anymore, it makes sense to ship the code with Boost.Asio (where we have already similar Windows I/O objects called random_access_handle and stream_handle - object_handle fits in nicely). Once I'm done with this, a major critical point should have been resolved. I'll go back then to Boost.Process code and help Jeff to finish https://github.com/JeffFlinn/boost-process. I'm not sure how far we are there. But as I don't remember any major obstacles, I'm confident that there are none. :) Boris

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[TTI] Review Result
by Joel falcou 02 Aug '11

02 Aug '11

This is the result summary for the Type Traits Introspection library by Edward Diener. The review have been on going from July 1st to july 17th and had generated a large amount of very interesting design discussion. The library received 5 Positive reviews and a few positive comments next to that. **The verdict is that, the TTI Library is ACCEPTED into Boost.** However, a few comments and concerns have been raised but are rather simple changes to perform and I am sure Edward will take these comments into account before releasing the library. Such comments include: * The main comment is the fact that Boost.TTI force the definitions of its meta-functions into the boost::tti. Concerns have been raised and requests made that the macro don't specify any namespace and let users bring the generated meta-functions in the namespace of their own liking. * The number of macros handling various corner cases has been raised as potentially too high. Effort to streamline the macro based interface has been requested. * Support for more compiler is needed. Some issues on ICC has been raised but are currently being looked upon (or fixed). * Naming scheme of the macro and of the generated meta-functions have to be refined to be 1/ more clear 2/ avoid some non-standard name starting with __ * Some more detailed and entry-level examples may be beneficial to the library * Pre-made macro for classical typedef like value_type or other std components has been proposed Thanks to all the participants and to Edward for this review.

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[Boost] [GSoC] [Checks] Issue with the design
by Pierre Talbot 02 Aug '11

02 Aug '11

Hello everyone. We talked a few days ago about the design of the check library (about the compile or run-time weight parameter.) Reminder : the weights are the contribution to the running sum of a digit in a number. I used and followed your ideas and suggestions that bring me to the policies class. I tried to extract the characteristics of a "generic" check and the weight is one of these. So I tried to implement the weight policy class : #define _WEIGHT_factory(z,n,unused) \ template<BOOST_PP_ENUM_PARAMS(n, int weight)> \ struct weight_policy \ { typedef typename boost::mpl::vector_c<int BOOST_PP_COMMA_IF(n) BOOST_PP_ENUM_PARAMS(n, weight)> weight ; } ; \ BOOST_PP_REPEAT_FROM_TO(1,BOOST_CHECK_LIMIT_WEIGHTS,_WEIGHT_factory,~) #undef _WEIGHT_factory But the compiler doesn't like the "struct template parameter overloading". Is a limit of the language ? Or am I doing it in the wrong way ? If it's impossible, I though that we could passed the weights to a function that aimed to "build" the vector_c type. While we speak about the design, what do you think about the policies class ? There are useful because the core of the algorithm is the same for every checks. Every critics or suggestions are welcomed, thank you, Pierre Talbot.

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