July 2013 - Boost - lists.preview.boost.org

Is there any interest in a library for actor programming?
by Charousset, Dominik 28 May '14

28 May '14

Hi, is there any interest in a library for actor programming? The library we've developed is a C++11 open source library named "libcppa". It is currently released under LGPL2, but re-releasing the library under the boost license is not an issue. You'll find all important links and ressources either under http://libcppa.org or on the GitHub project page: https://github.com/Neverlord/libcppa, including a user manual as HTML or PDF. We've also submitted a paper to the C++Now conference. What is actor programming? For those of you who aren't yet familiar with the actor model: actors basically represent tasks or services that communicate via message passing. In libcppa, actors are very lightweight (you can spawn literally millions of them) and scheduled cooperatively using a thread pool (although actors are allowed to opt-out of the cooperative scheduling). Some of the main strengths of this programming paradigm are: (1) network transparency, (2) race conditions are avoided by design, (3) a strong failure model that enables developers to build reliable distributed systems, and (4) the actor model addresses both concurrency (multiple actors on one host) and distribution (any number of actors on any number of hosts). Here's the classical hello world example: ---------------------------------------------------------------------------------- #include <string> #include <iostream> #include "cppa/cppa.hpp" using namespace std; using namespace cppa; void mirror() { // wait for messages become ( // invoke this lambda expression if we receive a string on_arg_match >> [](const string& what) { // prints "Hello World!" via aout (thread-safe cout wrapper) aout << what << endl; // replies "!dlroW olleH" reply(string(what.rbegin(), what.rend())); // terminates this actor ('become' otherwise loops forever) self->quit(); } ); } void hello_world(const actor_ptr& buddy) { // send "Hello World!" to our buddy ... sync_send(buddy, "Hello World!").then( // ... and wait for a response on_arg_match >> [](const string& what) { // prints "!dlroW olleH" aout << what << endl; } ); } int main() { // create a new actor that calls 'mirror()' auto mirror_actor = spawn(mirror); // create another actor that calls 'hello_world(mirror_actor)' spawn(hello_world, mirror_actor); // wait until all other actors we have spawned are done await_all_others_done(); // run cleanup code before exiting main shutdown(); } ---------------------------------------------------------------------------------- A message is simply a tuple of values that is pattern matched at the receiver. For example, " on_arg_match >> [](const string& what) {...}" defines a message handler that is called whenever a tuple with one single string element arrives. "on_arg_match" simply defines a pattern that matches the signature of the given lambda. Please have a look at the examples folder on GitHub (https://github.com/Neverlord/libcppa/tree/master/examples) or at the user manual (http://neverlord.github.io/libcppa/manual/) if you want to see more examples. Best regards, Dominik Charousset

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required toolsets
by Steven Watanabe 15 May '14

15 May '14

AMDG The list of required toolsets in explicit-failures-markup.xml is out-dated. Therefore, if no one objects, I propose setting it to the following: msvc-10.0, msvc-11.0, gcc-4.6, gcc-4.7, clang-darwin-11, clang-darwin-4.2.1, clang-linux-3.1, clang-linux-3.2, gcc-mingw-4.7, gcc-mingw-4.6 (two releases of each major compiler that appears in both the trunk and release regression tests) The sole effect of this is to determine which toolsets appear in the issues list: http://www.boost.org/development/tests/trunk/developer/issues.html In Christ, Steven Watanabe

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C++03 and C++11 ABI compatibility for compiled libraries
by Andrey Semashev 24 Jan '14

24 Jan '14

Hi, I would like to raise the issue of binary compatibility of compiled Boost libraries between C++03 and C++11. I faced this problem with gcc on Linux, but other compilers and platforms may be affected as well. To summarize the problem: * Most, if not all Linux distributions build packages in C++03 mode. This is also the default in gcc. * Some Boost libraries conditionally use C++11 features in their binary interfaces (see [1] as an example). This makes C++03 and C++11 versions of the library binary incompatible. * Given that, users are unable to use C++11 in their code that uses Boost because of linker failures. I don't have the complete list of the offending C++11 features that break ABI, but it would seem that at least scoped enums and rvalue references are among them. Are there any more? I would like to hear opinions on the possible course of action to tackle this problem. Currently, I see 2 choices: 1. Avoid using C++11 features in binary interfaces. This may also mean avoiding STL types in binary interfaces, if they differ between C++03 and C++11 (I didn't verify that). This is my suggested hotfix solution for Boost.Filesystem [1] and the approach I took in Boost.Log. Obviously, this cripples code and error prone, but it keeps a single binary that can be used from any flavor of C++ on the user's side. 2. Compile different versions of Boost libraries, for each supported C++ version. The C++ version should be encoded into the library file names, so that different versions can coexist. This would require changes in Boost.Build and autolinking support code, but I think this would be a better long-term solution. Opinions? [1] https://svn.boost.org/trac/boost/ticket/6779

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[Macro]Test Case grouping using Traits
by Hemanth Choudary M V (RBEI/ETA1) 13 Jan '14

13 Jan '14

Hello, I have observed that in native unit test framework(c++), there is an option to group test cases using attributes which are reflected as traits in the Test Explorer window in MS VS2012. Following is a an example of the same: BEGIN_TEST_METHOD_ATTRIBUTE(TestMethod3) TEST_OWNER(L"SuperMan") TEST_PRIORITY(2) TEST_METHOD_ATTRIBUTE(L"Category",L"Slow") END_TEST_METHOD_ATTRIBUTE() TEST_METHOD(TestMethod3) { Assert::AreEqual(2,6); } How can this be achieved via Boost Unit Test Library? Are there macros to achieve the same? Mit freundlichen Grüßen / Best Regards, Hemanth Choudary MV RBEI/ETA1

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[filesystem] fix recur_dir_itr_imp::increment(system::error_code* ec) in 1.54.0
by claudio.bley＠gmail.com 19 Dec '13

19 Dec '13

Hi. What's happening to the filesystem library? It seems there's no progress on any tickets in the bug tracker? Referring to https://svn.boost.org/trac/boost/ticket/6821#comment:5 Could we get this fix into 1.54.0, please? BTW, sorry for any confusion - I "managed" to comment on the wrong ticket... https://svn.boost.org/trac/boost/ticket/5403 would've been more appropriate, I guess. Claudio -- Claudio

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RFC: edit_distance / edit_alignment library
by Erik Erlandson 18 Dec '13

18 Dec '13

Boost Community, I cooked up a library that provides a pair of functions: edit_distance() and edit_alignment(). The library currently lives here: https://github.com/erikerlandson/edit_distance Some short example programs are here: https://github.com/erikerlandson/edit_distance/tree/master/examples A few example expressions: // the edit distance (aka levenshtein distance) unsigned dist = edit_distance("abc", "bcd"); // using a custom cost function for insertion, deletion, substitution unsigned dist = edit_distance("abc", "bcd", custom_cost_function()); // accepts arbitrary sequences, ranges, range adaptors unsigned dist = edit_distance(as_vector("abc"), as_list("bcd") | boost::adaptors::reversed); // obtain the edit distance and the list of the edit operation codes (in output iterator) unsigned dist = edit_alignment("abc", "bcd", std::ostream_iterator<edit_opcode>(std::cout, "")).second; // adaptors to add edit operation costs and sequence elements to the edit operation output unsigned dist = acquire<elements>(acquire<costs>(edit_alignment))("abc", "bcd", std::ostream_iterator<boost::tuple<edit_opcode, unsigned, char, char> >(std::cout, "")).second; I'm interested in community feedback on whether these would be a useful addition to boost::algorithms. I envision these as the first additions to an eventually-larger library of other kinds of string distances, dynamic programming, and other algorithms for sequence alignment.

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How to center an element in Boost QuickBook?
by Niall Douglas 10 Oct '13

10 Oct '13

As the documentation for proposed Boost.AFIO comes together for this week's GSoC Milestone 1 (feel free to check it out at https://ci.nedprod.com/job/Boost.AFIO%20Build%20Documentation/Boost.AFIO_Doc umentation/?), a problem has emerged. We'd like a matrix table containing ticks and crosses, and building such a thing in QuickBook is easy. However, we'd also like to center the ticks and crosses in each table cell, otherwise it looks poor. Is there some way I haven't realized of aligning content in Boost QuickBook, or even BoostBook itself? The DocBook documentation suggests one can do a '''<entry align="center">'''__tick__'''</entry>''' (the triple single ticks escape from QuickBook into BoostBook). However unfortunately BoostBook defines CSS which overrides the per-cell alignment :( Thanks in advance for the help. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

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lots of warning with gcc-4.8.1 + boost-1.54.0
by Neal Becker 04 Oct '13

04 Oct '13

Lots of warnings like this: ./boost/bind/arg.hpp:37:22: warning: typedef ‘T_must_be_placeholder’ locally defined but not used [-Wunused-local-typedefs] when building 1.54.0 with gcc-4.8.1 (fedora f19)

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[accumulators] Help understanding implementation of weighted accumulators
by Gabriel Redner 02 Oct '13

02 Oct '13

Hi folks, I am trying to implement a weighted accumulator, but I'm having trouble understanding a few things about the existing ones. Looking at the implementation of weighted_sum, I see (weighted_sum.hpp:37): template<typename Args> weighted_sum_impl(Args const &args) : weighted_sum_( args[parameter::keyword<Tag>::get() | Sample()] * numeric::one<Weight>::value ) { } My questions are: - It's taking the first sample from the args and multiplying it by a weight of 1. Isn't this wrong - ignoring the real weight of this sample? Shouldn't this produce incorrect results? - I've never understood anyways how there can be an initial argument during construction of the accumulator. I haven't found any explanation in the docs beyond "Maybe there is an initial value in the argument pack". Maybe? How? Probably more questions later. Thanks, -Gabe

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[thread] semaphore
by Tim Blechmann 02 Oct '13

02 Oct '13

hi all, i've submitted an implementation of semaphores for boost.thread to trac [1]. they provide an interface similar to boost.interprocess semaphores, with the exception of having chrono-style try_wait_for and try_wait_until members for timed_wait. the patch provides the following implementations: * win32 semaphores (tested with windows 8) * posix semaphores (tested with linux) * dispatch semaphores (tested with osx 10.8) * mutex/condition_variable/counter emulation the native implementations are much faster than the fallback, in microbenchmarks with high contention, i've seen a speedup of 30 to 80. would be great if they can be incorporated into boost.thread. comments/suggestions on the API are highly appreciated. cheers, tim [1] https://svn.boost.org/trac/boost/ticket/8797

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Re: [boost] [thread] synchronized_value: value and move semantics
by Andrey Semashev 24 Sep '13

24 Sep '13

On Wed, Feb 20, 2013 at 10:02 PM, Vicente J. Botet Escriba < vicente.botet(a)wanadoo.fr> wrote: > > Hi, > > boost::synchronized_value (not released yet [1][2][3]) is based on [4]. > See below part of this paper adapted to the Boost.Thread interface. > > Currently boost::synchronized_value is in addition Copyable and Swappable. > I was wondering if it is worth adding value and move semantics to > synchronized_value. Making it EqualityComparable, LessThanComparable and > Movable if the underlying type satisfy these requirements will allow to > store them on a Boost.Container/C++11 container. > > Do you see something completely wrong with this addition? > Has some of you had a need for this? Could you share the context? > Sorry, I missed this discussion somehow. I've taken a quick look at the interface and have a few questions: 1. Why are there strict_lock_ptr and unique_lock_ptr? What are the differences and why we can't have one such ptr (presumably, unique_lock_ptr)? 2. I find value() and get() a bit confusing, since it is not apparent what is the difference between them. Maybe value() could be renamed to get_ref() or unsafe_get()? 3. Am I correct that having strict_lock_ptr/unique_lock_ptr acquired by calling synchronize() will not deadlock with operator-> when a non-recursive mutex is used?

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[Operators] empty_base should be untemplated?
by Andrew Ho 21 Sep '13

21 Sep '13

I've noticed about the empty_base class is that it's templated with type T, and I don't think it should be. Fyi, the empty_base class is there to turn multiple inheritance into a single inheritance chain (due to compiler deficiencies/object size bloat on at least Visual Studio). I don't see why this empty_base should be templated, and it would be better suited if it wasn't since all I can think it does is make the compiler work harder. Does anyone know why it was templated to begin with? Additionally, are we safe to change empty_base to be not use templates?

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[asio] boost::asio::async_connect reports success on failure
by Ben Pope 13 Sep '13

13 Sep '13

Hi all, I've found a regression between 1.53 to 1.54; if you compile boost/libs/asio/example/cpp11/chat/chat_client.cpp and point it at a host and port that doesn't exist or refuses the connection, instead of coming back with an error, such as host not found or connection refused, it reports success (on the conversion to bool). (you might want to embellish the example with a std::cout << error_code.message() << std::endl;) This appears to be the case across Linux, Darwin, iOS and Android :( synchronous connect seems to work correctly (i.e., echo/blocking_tcp_echo_client.cpp) Ben

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Removing old config macro and increasing compiler requirements.
by Stephen Kelly 12 Sep '13

12 Sep '13

Hi there, I've been working on the modularization effort from a CMake point of view, and from an 'actual modularization' point of view, looking at interdependencies: http://thread.gmane.org/gmane.comp.programming.tools.ryppl.devel/9/focus=26 I'd like to start on reducing interdependencies, and I'd like to start reasonably small, as no-one in the boost community knows me and see how it goes from there. I'm very active in CMake, Qt and KDE. Currently, in the modularized boost repos, boost::config and boost::core depend on each other. I listed 3 ways of fixing this on the ryppl list: http://thread.gmane.org/gmane.comp.programming.tools.ryppl.devel/201 My preference is the removal of BOOST_NO_EXPLICIT_FUNCTION_TEMPLATE_ARGUMENTS, and requiring compilers to have the feature. That way boost/config/suffix.hpp will no longer need to include boost/{non_,}type.hpp. My preference is increasing the compiler requirement, because that may open up more similar opportunities for reducing dependencies and interdependencies throughout boost. Grepping indicates that that means increasing the compiler requirements to something like __DMC__ > 0x840, GCC > 3.2, BOOST_INTEL_CXX_VERSION > 500, VC++ > 7.0. Comments? Thanks, Steve.

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[thread] Can boost::this_thread::sleep_for() totally stop the thread?
by Klaim - Joël Lamotte 03 Sep '13

03 Sep '13

I'm having, sometime, trouble with a rare heisenbug (rare but appearing several times a week). I described it there: http://stackoverflow.com/questions/17918548/can-windows-totally-stop-a-thre… There I ask if it's possible for windows to totally stop a thread that is sleeping too often. As I'm using boost::thread for sleeping this specific thread that, for unknown reason, sometime totally stop working, I'm also wondering if the boost::this_thread() implementation could not be doing something that the OS might not like? ----- I'll report the content of the page here: Can Windows totally stop a thread if it's sleeping too often? I have a rare heisenbug in a multi-threaded application where the main thread, and only this thread, will just do nothing. As it's an heisenbug it's really hard to understand why this is happening. The main thread is basically just looping. In the loop, it check several concurrent priority queues which contain tasks ordered by time to be executed. It pop a task, see if it's time to execute it. If it's time, it will just schedule it into TBB's task scheduler (using a root task which is the parent of all other tasks). If it's not time, the task is pushed again in the priority queue. That's for one cycle. At the end of the cycle, the main thread is put to sleep for a very short time that I expect will be longer in practice but it's not really a problem, I just don't want it to use too much resources when not necessary. Litterally: static const auto TIME_SCHEDULED_TASKS_SPAWN_FREQUENCY = microseconds(250); while( !m_task_scheduler.is_exiting() ) // check if the application should exit { m_clock_scheduler.spawn_realtime_tasks(); // here we spawn tasks if it's time this_thread::sleep_for( TIME_SCHEDULED_TASKS_SPAWN_FREQUENCY ); } m_clock_scheduler.clear_tasks(); m_root_task.wait_for_all(); I have a special task that just log a "TICK" message each second. It is automatically rescheduling until the end of the program. However, when the heisenbug appear, I can see the "TICK" disappearing and the application not doing anything else than the work that occurs in non-main threads. So it appear that only the main thread is touched. The problem can come from different places, maybe in the scheduling logic, but then it's also the only thread that have a sleep call. That sleep is a boost::this_thread::sleep_for(). My question is: **Is it possible that Windows (7 64bit) consider the main thread to be sleeping often and decide that it should sleep for a longer period of time than asked or be definitely ended?** I expect that it is not possible but I would like to be sure. I didn't find any precision on this in online documentation so far. ----- I really suspect that the problem can't come from the sleeping function but I need to eliminate each potential source of problem to isolate it. Thanks for your time. Joel Lamotte

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[multimethods] Proposal: Open Multi-Methods
by Jean-Louis Leroy 01 Sep '13

01 Sep '13

Hi, I am working on library that pretty much implements what Pirkelbauer, Solodkyy and Stroustrup describe in their paper "Open Multi-Methods for C++" - although there are some divergences. I have posted it on GitHub: https://github.com/jll63/multimethods. Please examine the files in the "examples" directory to get an idea of how to use it. Salient features are: * syntax: is relatively uncluttered. There are no limitations on the number of virtual arguments. Virtual and non-virtual arguments can be arbitrarily mixed. Multiple inheritance is supported, with some limitations - see below. * speed: close to a virtual function call when the hierarchies involved in the virtual arguments collaborate with the library. Calling a method that does nothing, with a single virtual argument in a single inheritance hierarchy is 33% slower than the equivalent virtual function call. The difference becomes unnoticeable if the functions perform a few simple maths operations. See tests/benchmarks.cpp. * size: the dispatch table is constructed in terms of class groups. This results, most of the time, in a table devoid of redundancies. The size is bounded by the product of the number of specializers - not classes - in each dimension. * support for "foreign" class hierarchies: the library can be used without modifications to existing classes, at the cost of lower performance. Collaborating and foreign arguments can be freely mixed. Performance is still quite good, see the benchmarks. * next: a pointer to the next most specialized method is available inside method specializations - see examples/next.cpp. Alternatively, it is possible to call a specialization directly. Current limitations are: * restrictions on hierarchy: the classes involved in a method call must have a single root. Repeated inheritance is not supported. Multiple inheritance is supported, provided that the two conditions above are respected. * no overloading: multi-methods are implemented as constexpr function objects. This does not allow for overloading. This restriction can be easily side-stepped by wrapping multi-methods with different names in a set of overloaded functions. I know how to make multi-methods functions instead of objects, at the cost of a slightly less nice syntax for specializers. This is open to discussion. Besides, the library differs from Stroustrup et al's paper on the following points: * a specializer specializes only one multi-method: what would "next" mean otherwise? What would its static type be? * pure multi-methods are allowed: if called, an exception is thrown. This seems a better choice given that most of the time the declared virtual arguments will be abstract classes anyway. The library is essentially feature complete (if anything ever is). I am now going to work on the documentation, a build system, some clean up and compatibility (I tested it only with g++ 4.7.2 only so far). Is there interest in the Boost community for this stuff? If yes, I will adapt it to the guidelines and submit it for formal review. Of course, suggestions are welcome. Thank you for your time, Jean-Louis Leroy

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[type_triats] [move] is_copy_constructible<T> trait
by Antony Polukhin 26 Aug '13

26 Aug '13

Hi, I have an implementation of is_copy_constructible<T> trait. It works great with C++11, in C++03 it detects constructors assuming that if type is derived from boost::noncopyable or uses BOOST_MOVABLE_BUT_NOT_COPYABLE macro - it has no copy constructor. Questions are: * May I add that trait to trunk version of Boost.TypeTraits (with documentation and tests, as usual)? * May I or Boost.Move maintainer apply this patch to BOOST_MOVE_IMPL_NO_COPY_CTOR_OR_ASSIGN in boost/move/core.hpp : #ifdef BOOST_NO_CXX11_DELETED_FUNCTIONS #define BOOST_MOVE_IMPL_NO_COPY_CTOR_OR_ASSIGN(TYPE) \ private:\ TYPE(TYPE &);\ TYPE& operator=(TYPE &);\ + public: \ + typedef int boost_move_no_copy_constructor_or_assign; \ + private: \ // #else Why do I need this trait? Well, it allows to implement move_if_noexcept() that is required for circular_buffer and possibly for other containers. -- Best regards, Antony Polukhin

2 4

Pre-build MSVC Boost binaries
by Fredrik Orderud 13 Aug '13

13 Aug '13

Over the last year, I've set up a small SourceForge "WinBin" project [1] for distributing Microsoft Windows binaries for Boost (and some other projects). The repository is sorted by Boost version, compiler version and shared vs. static linking. Each file archive contains pre-build boost in debug/release for both 32/64-bit, following a include/lib[64]/bin[64] folder structure. There also seems to be some other sources for pre-built boost around (e.g. https://sourceforge.net/projects/boost/files/boost-binaries/ and http://boost.teeks99.com/bin/) However, these do not seem to provide boost built for both static and shared linking. Also, they do not appear to adhere to the "quasi standard" include/lib[64]/bin[64] folder naming convention used by many libraries. Finally, they seem to lack information on which version of python (and possibly other 3rd party SW) they are compiled against. Therefore, I decided to set up my own boost-binaries webpage. Please let me know if you might be interested in either improving the "WinBin" project, or somehow joining forces to merge the various sources of Boost binaries into a single, more "authoritative" repository. I would be more than happy to shut WinBin down if "similar enough" binaries can be downloaded elsewhere. Thanks in advance, Fredrik Orderud [1] https://sourceforge.net/projects/winbin/files/boost/

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Line endings fixes
by Vitaly Budovski 13 Aug '13

13 Aug '13

Hi, Please see the attached files. boost_endings1.patch just sets some of the cpp and other text files to have file endings consistent with the rest of the repository. boost_endings2.patch may be controversial as it does the same but for the svg files. Some of them are marked as text, others as binary. It's a real mess. Most of the svg files are generated from other sources so should probably be omitted from the repository and simply regenerated when docs are built. Came across these issues when checking out the modularised boost git repository. Regards, Vitaly

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[mixin] New library reminder
by Borislav Stanimirov 11 Aug '13

11 Aug '13

Hello, Some of you might remember the previous discussion on the subject (archived here: http://lists.boost.org/Archives/boost/2013/01/200598.php) Anyway, in short, I'm developing a library with the intention to formally submit it to Boost by the end of the year. You can find it here: https://github.com/iboB/boost.mixin The latest news about it is that I think that the library's features for the formal submission are done and all that's left are minor tweaks, bug fixes, tests, examples, and, most importantly, a complete documentation. In the meantime, I again invite you all to check it out. Any comments, suggestions, and questions will be greatly appreciated. Thanks, -- Borislav

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Boost 1.54 build problem: --without-context not honoured?
by Steve M. Robbins 11 Aug '13

11 Aug '13

Hi, I'm digging into a build problem and noticed that even though I specify "./bjam --without-context", Boost.Context is still built! The bjam configuration output states that Context is not to be built: Component configuration: - atomic : building - chrono : building - context : not building - coroutine : building - date_time : building - exception : building But it is built nonetheless. This causes a build failure for architectures which are not supported; see build log [1]. Compare that to the build for 1.53 [2] which works fine. I've diffed the libs/context directory between 1.53 and 1.54 and nothing jumps out at me as the cause. Has anyone noticed and fixed this already? Thanks, -Steve [1] https://buildd.debian.org/status/fetch.php?pkg=boost1.54&arch=ia64&ver=1.54… [2] https://buildd.debian.org/status/fetch.php?pkg=boost1.53&arch=ia64&ver=1.53…

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[boost/spirit] numeric policy
by Brian Schrom 07 Aug '13

07 Aug '13

I've had the case where I needed to retain formatting information for a number (general, fixed, scientific) and was nicely accomplished by extending the policy, but needed to have a begin_parse() and end_parse() for the policy to be complete. It seems that it makes some sense or is this accomplished another way? Maybe something to consider for policies in general? Index: qi/numeric/real_policies.hpp =================================================================== --- qi/numeric/real_policies.hpp (revision 85166) +++ qi/numeric/real_policies.hpp (working copy) @@ -28,6 +28,18 @@ static bool const allow_trailing_dot = true; static bool const expect_dot = false; + template <typename Attribute> + static void + begin_parse(Attribute& attr_) + { + } + + template <typename Attribute> + static void + end_parse(Attribute& attr_,bool /* result */) + { + } + template <typename Iterator> static bool parse_sign(Iterator& /*first*/, Iterator const& /*last*/) Index: qi/numeric/detail/real_impl.hpp =================================================================== --- qi/numeric/detail/real_impl.hpp (revision 85166) +++ qi/numeric/detail/real_impl.hpp (working copy) @@ -133,6 +133,7 @@ parse(Iterator& first, Iterator const& last, Attribute& attr, RealPolicies const& p) { + p.begin_parse(attr); if (first == last) return false; Iterator save = first; @@ -257,6 +258,7 @@ // If we got a negative sign, negate the number traits::assign_to(traits::negate(neg, n), attr); + p.end_parse(attr, true); // maybe this should return a bool and be the return value? // Success!!! return true; }

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[intrusive] Compilation problem with gcc 4.7
by Hartmut Kaiser 07 Aug '13

07 Aug '13

In code which compiled just fine I'm now seeing: In file included from /opt/boost/trunk-debug/boost/intrusive/slist_hook.hpp:24:0, from /opt/boost/trunk-debug/boost/intrusive/slist.hpp:21, from /opt/buildbot/slave/hpx_gcc47_x8664_boosttrunk_debug/build/hpx/lcos/local/mu tex.hpp:23, from /opt/buildbot/slave/hpx_gcc47_x8664_boosttrunk_debug/build/hpx/runtime/compo nents/server/wrapper_heap.hpp:20, from /opt/buildbot/slave/hpx_gcc47_x8664_boosttrunk_debug/build/hpx/runtime/compo nents/server/managed_component_base.hpp:13, from /opt/buildbot/slave/hpx_gcc47_x8664_boosttrunk_debug/build/hpx/lcos/base_lco .hpp:12, from /opt/buildbot/slave/hpx_gcc47_x8664_boosttrunk_debug/build/hpx/lcos/base_lco _with_value.hpp:11, from /opt/buildbot/slave/hpx_gcc47_x8664_boosttrunk_debug/build/hpx/performance_c ounters/counters.hpp:12, from /opt/buildbot/slave/hpx_gcc47_x8664_boosttrunk_debug/build/hpx/runtime/compo nents/server/runtime_support.hpp:32, from /opt/buildbot/slave/hpx_gcc47_x8664_boosttrunk_debug/build/hpx/runtime.hpp:1 2, from /opt/buildbot/slave/hpx_gcc47_x8664_boosttrunk_debug/build/src/hpx_main.cpp: 7: /opt/boost/trunk-debug/boost/intrusive/detail/generic_hook.hpp: At global scope: /opt/boost/trunk-debug/boost/intrusive/detail/generic_hook.hpp:134:55: error: declaration of typedef struct boost::intrusive::hooktags<typename GetNodeAlgorithms::type::node_traits, Tag, LinkMode, BaseHookType> boost::intrusive::generic_hook<GetNodeAlgorithms, Tag, LinkMode, BaseHookType>::hooktags [-fpermissive] /opt/boost/trunk-debug/boost/intrusive/detail/generic_hook.hpp:84:8: error: changes meaning of hooktags from struct boost::intrusive::hooktags<typename GetNodeAlgorithms::type::node_traits, Tag, LinkMode, BaseHookType> [-fpermissive] Ion, could you fix this, please? Regards Hartmut --------------- http://boost-spirit.com http://stellar.cct.lsu.edu

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[move] Documentation example typo.
by Jurko Gospodnetić 04 Aug '13

04 Aug '13

Hi. Just reporting a slight typo in boost::move library documentation's file_descriptor class example code for closing the OS file descriptor. It says: > if(!os_descr_) operating_system_close_file(os_descr_); in its destructor & assignment operator when it should in fact say: > if(os_descr_) operating_system_close_file(os_descr_); [notice the removed ! operator] Hope this helps. Best regards, Jurko Gospodnetić

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[asio] condition_variable for coroutine-powered ASIO
by TONGARI J 04 Aug '13

04 Aug '13

Hi, Since Boost 1.54, ASIO introduced yield_context, which is very helpful to alleviate the pain of writing async ops. Unlike multi-threading, with cooperative multi-tasking, generally we don't have to worry about synchronization, but we still need some sort of mechanism to sync the coroutines in cases like producer-consumer for waiting the data... While I haven't seen any sync tool for asio/coroutine, having a condition_variable or such may be very useful, what do you think? Attached is the poor-man's implementation...

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