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Re: [Boost-users] [boost] [Review.Coroutine] Some comments
by Oliver Kowalke 05 Sep '12

05 Sep '12

> * I don't know if showing the signature in the documentation will be > more informative. OK > * Could you add the following noexcept specifier? OK > * As the template class Allocator is not used to allocate internal > memory of the coroutine class. Could the Allocator parameter be renamed > StackAllocator? OK > * Could you add an standard Allocator parameter as e.g. the one of > packaged_task? > > C++ International Standard > > * I understand that the Boost.Context Allocator parameter is part od the > class, as context is a low-level class, but coroutine is more high > level. Is there a possibility to type erase the StackAllocator (and > preceding Allocator) template parameter, as packaged_task do? This will > allow to store coroutines (and generators) with the same signature in a > container even if they don't share the Allocator. You mean coroutine would have two allocators - one for allocating internal memory and one for allocating the stack? Removing the StackAllocator from the template arguments of coroutine should not that problem (would require an internal pointer to an internal interface - maybe detail::context_exec is a candidate). I've some concerns about having two allocator objects in coroutine's ctor . > * Parameters and move semantics. Could the signature parameters be > rvalue references? > > R operator()(A0 a0, ..., A9 a9); Hmmm - this would require a second version of opertor() and all arguments are moveable?! R operator()(BOOST_RV_REF( A0) a0, ..., BOOST_RV_REF( A)) a9); > I'm asking this because I think that Boost.Tuple has not implemented yet > move semantics. don't know - would that be an issue > * What about moving some of the coroutine/generator optional parameters > to a coro::attributes class > > std::size_t size = ctx::default_stacksize(), > flag_unwind_t do_unwind = stack_unwind, > bool preserve_fpu = true, instead of passing those threee params as args to coroutine ctor? good point > * Usually (at least in the C++ standard) a function doesn't throws > because of its preconditions are not satisfied. then assert? pre-conditions should be checked but how should I react if I get garbage from the user? > This should be coherent with > > > |Result operator()()| > > Preconditions: > > |*this| is not a /not-a-generator/, |! is_complete()|. > > which doesn't throws any specific exception if the preconditions are not > satisfied. does an assert - OK the I'll replace throwing excpetions be assertions > Documentation > ========= > > coroutine.html > > s/it can migrated between threads/it can migrate between threads/ OK > s/yield_return/yield_break/ > > * documentation for the following constructor is missing in the reference > > template< typename Fn > > coroutine( Fn && fn, > std::size_t size = ctx::default_stacksize(), > flag_unwind_t do_unwind = stack_unwind, > bool preserve_fpu = true, > Allocator alloc = Allocator() ); OK I think it will be easy to incorporate your suggestions - but during the boost.context review I was told not to modify the reviewd library (if the review is still on-going). regards, Oliver

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can different versions of boost coexist in an executable?
by Nathan Ridge 05 Sep '12

05 Sep '12

Hello, I am developing a C++ library, which I distribute in binary form as a static library. The implementation of my library uses Boost, but the interface does not, so I completely shield my users from the Boost dependency by linking the Boost object files that my implementation requires into the static library. Suppose a client of my library uses Boost in their own code. When they link their executable, the linker now sees two copies of some Boost libraries: the copy in my static library, and their own copy that they are linking. It seems that the linker only keeps one of the two and discards the other. If the Boost version that I linked into my static library is different from the Boost version my client uses, then one of my code and their code will be linked to a different version of Boost that the one it was compiled against, leading to a crash. I suppose one way to rectify this problem would be for me to document what version of Boost libraries I compiled and linked against, and require that if my clients use Boost themselves, they use the same version. However, I dislike this solution for two reasons: 1) It exposes my library's dependence on Boost, which was meant to be an implementation detail. 2) It limits my clients to using a particular version of Boost. They may have good reasons for using an older (or newer!) version instead. I would much prefer if the linker kept both copies of the Boost libraries in the executable, and each piece of code (mine and my client's) used whichever version of the libraries it was compiled against. Can this be accomplished? Thanks, Nate

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[fusion] Wrapping a Fusion sequence
by Agustín K-ballo Bergé 04 Sep '12

04 Sep '12

I'm looking for a way to create a Fusion sequence wrapper that is itself a Fusion sequence and forwards all 'calls' to its wrapped sequence. Something in the lines of template< typename Sequence > struct sequence_wrapper { explicit sequence_wrapper( Sequence const& s ) : seq( s ){} Sequence seq; }; where sequence_wrapper< Sequence > is a Fusion sequence as well, and works just as Sequence would. The reason I need this is that I have several functions that operate on Fusion sequences (where all elements satisfy some special requirements), and I would like to add some syntax sugar for which I need a custom type to add overloaded operators to. I do not need the result of operations on a sequence_wrapper to return a sequence_wrapper as well, only the syntax sugar related calls would return a (manually) wrapped sequence. For instance, appending elements to a sequence using the comma operator (somewhat of a Boost.Assign for Fusion sequences): template< typename Sequence, typename T > sequence_wrapper< typename boost::fusion::result_of::push_back< Sequence const& , T >::type > operator,( Sequence const& seq, T const& v ) { return sequence_wrapper< typename boost::fusion::result_of::push_back< Sequence const& , T >::type >( boost::fusion::push_back( seq, v ) ) ; } What would be the best way to achieve this (if it is indeed supported by the library)? I'm particularly trying to avoid creating a Fusion sequence from scratch, as I would like to use whatever sequence is returned by Fusion operations. Would inheritance + specialization of `tag_of` to return the tag of the wrapped sequence just work? Or will I need to define a tag of my own and implement all required functions to just forward the call? Thank you in advance. Agustín K-ballo Bergé.- http://fusionfenix.com

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Trying to compile and use boost on proprietary complier similar to MPICH2 CXX
by Chris 04 Sep '12

04 Sep '12

Hi all, hope this is the right list for my question. So here it goes: When it try to use boost using a proprietary MPIC++ compiler I have no control over, I get the following errors: In file included from ../boost_1_43_0/boost/thread/detail/platform.hpp:17, from ../boost_1_43_0/boost/thread/thread.hpp:12, from ../boost_1_43_0/boost/thread.hpp:13, from test.cpp:37: ../boost_1_43_0/boost/config/requires_threads.hpp:47:5: error: #error "Compiler threading support is not turned on. Please set the correct command line options for threading: -pthread (Linux), -pthreads (Solaris) or -mthreads (Mingw32)" In file included from ../boost_1_43_0/boost/thread/thread.hpp:12, from ../boost_1_43_0/boost/thread.hpp:13, from test.cpp:37: ../boost_1_43_0/boost/thread/detail/platform.hpp:67:9: error: #error "Sorry, no boost threads are available for this platform." In file included from ../boost_1_43_0/boost/thread.hpp:13, from test.cpp:37: ../boost_1_43_0/boost/thread/thread.hpp:19:2: error: #error "Boost threads unavailable on this platform" The thing is, when I use the standard mpicxx from MPICH2, things work out fine. I'm now trying to find out if the problem lies in the complier, or if I simply did not compile and bootstrap boost properly. What I did when building boost is the following: ./bootstrap.sh --with-libraries=date_time,filesystem,serialization,iostreams,system,thread,mpi ./bjam cxxflags="-O2" release threading=multi link=static After bootstrap, I tried to manually edit the user-config.jam to add "using mpi ;" and explicitly added the path to the compiler, but this all did not change the above mentioned error when I try to compile my code that uses boost. Is this enough information for you to judge if I might have overlooked something when building boost? Many thanks, Chris

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filesystem directory_iterator run-time error during construction after upgrading to OSX Lion
by Martin Searancke 04 Sep '12

04 Sep '12

I have just upgraded my Mac to Lion and code that worked fine under snow leopard is giving me a run-time exception when constructing a directory_iterator. The error I am getting is "malloc: pointer being freed was not allocated" The line in question that raises this error is: for ( directory_iterator itr( my_path ); itr != end_itr; ++itr ) taken directly from the example and working fine under windows. This is version 1.49 installed with MacPorts. Is this a known problem? I found some vague references to a similar problem in an earlier version of boost but no solution. I have confirmed that I only have 1 copy of the headers and libs on the system and in the correct path. The date stamp on the files matches the last time I did a macports update so this should be the matching library for the header. Please note that I am a real novice to Mac development and have only just started porting code from windows for less than a month. Thanks in advance, Martin

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Re: [Boost-users] compilation problems with thread/chrono & boost 1.51 & HPUX
by Avi Bahra 04 Sep '12

04 Sep '12

>>On 3.9.2012. 10:26, Avi Bahra wrote: >>> Can any one suggest *any* hacks/workarounds that gets me pass these errors. >>> Is it possible to use gcc on HPUX with boost 1.51 ? >> >>The docs for boost thread 1.51 say this: >> >>Boost.Thread uses by default Boost.Chrono for the time related >>functions. For backward compatibility and also for compilers that don't >>work well with Boost.Chrono the user can define >>BOOST_THREAD_DONT_USE_CHRONO. If BOOST_THREAD_DONT_USE_SYSTEM is defined >>then BOOST_THREAD_DONT_USE_CHRONO is defined implicitly. >> >>BOOST_THREAD_USES_CHRONO is defined when Boost.Thread uses Boost.Chrono. I have already tried BOOST_THREAD_DONT_USE_CHRONO and it has no effect. It appears that some of headers files are not guarded with this. In my case $BOOST_ROOT/boost/chrono/system_clocks.hpp $BOOST_ROOT/boost/ratio/detail/overflow_helpers.hpp $BOOST_ROOT/boost/thread/future.hpp do not compile, Also Is it possible to make a request to change: $BOOST_ROOT/boost/thread/future.hpp line:603 for(count_type i=0;i<count;++i) { #if defined __DECCXX || defined __SUNPRO_CC locks[i]=boost::unique_lock<boost::mutex>(futures[i].future_->mutex).move(); #else locks[i]=boost::unique_lock<boost::mutex>(futures[i].future_->mutex); #endif } T0: for(count_type i=0;i<count;++i) { #if defined __DECCXX || defined __SUNPRO_CC || defined __hpux locks[i]=boost::unique_lock<boost::mutex>(futures[i].future_->mutex).move(); #else locks[i]=boost::unique_lock<boost::mutex>(futures[i].future_->mutex); #endif } Best regards, Ta, Avi

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[traits, fusion, mpl] Basic question about is_base_of and template ancestors
by Rindeberg Magnus 04 Sep '12

04 Sep '12

Hello List! I have an issue understanding how to combine CRTP with the "is_base_of" trait when iterating over a fusion vector. I have tried to illustrate my problem in the test program below. The idea is to first "do stuff" to all instances of types derived from A and then "do stuff" to the ones derived from B. I just don't know what to write instead of "WHAT_GOES_HERE?" below. I have tried to use "::boost::mpl::_" in different ways to get the "type" type of B but failed miserably every time. I'm also curious about how to negate the "is_base_of" predicate. I tried using "not_<>" but that didn't work at all... Very thankful for any and all help! // Magnus P.S. Sorry if this question has been answered already! I have looked at the documentation, searched archives and the web but couldn't find the solution. Maybe I searched using the wrong keywords... #include <boost/type_traits.hpp> #include <boost/mpl/vector.hpp> #include <boost/fusion/include/mpl.hpp> #include <boost/fusion/container.hpp> #include <boost/fusion/include/at_key.hpp> #include <boost/fusion/include/for_each.hpp> #include <boost/fusion/include/filter_if.hpp> struct dostuff { template<typename T> void operator()(T const & x) const { // Do stuff here! } }; template<class D> struct A { }; template<class D, typename T> struct B { typedef T type; }; struct derived_from_A : public A<derived_from_A> { }; struct derived_from_B : public B<derived_from_B, int> { }; typedef ::boost::mpl::vector<derived_from_A, derived_from_B>::type typelist_type; ::boost::fusion::result_of::as_set<typelist_type>::type typeset_; int main(int argc, char ** argv) { dostuff ds; // This seems to be working! ::boost::fusion::for_each( ::boost::fusion::filter_if < ::boost::is_base_of<A< ::boost::mpl::_>, ::boost::mpl::_> > (typeset_), ds); #if(0) // Don't know how to do this! Preferably I'd like to check for inheritance from B. // If that isn't possible I'll settle for "not inheriting from A". ::boost::fusion::for_each( ::boost::fusion::filter_if < ::boost::is_base_of<B< ::boost::mpl::_, WHAT_GOES_HERE? >, ::boost::mpl::_> > (typeset_), ds); #endif }

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Boost source code ?
by Sajith Kariyawasam 04 Sep '12

04 Sep '12

Hi all, Could any one of you point me to Boost source repository ? Im planning to build from the source. I got nothing in this link http://www.boost.org/users/download/#repository -- Best Regards Sajith

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a client for echo server example
by Goran 04 Sep '12

04 Sep '12

Hi all, I took a look into asio and "boost_asio/example/echo/async_tcp_echo_server.cpp". This example is clear. But I'm looking for something like an "async tcp echo client". The client should send every second one status message. Maybe client is not the correct word. My desired architecture should be "slave server" <--> "master server" where "master server" sends an "ACK" to "slave server" for every "DATA" packet "master server" receives. Something similar to an echo / ping pong server. Can someone provide hints or even an example for a "slave server" similar to "boost_asio/example/echo/async_tcp_echo_server.cpp"? Thanks in advance! Goran

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problems in compiling application using IBM XL C/C++ V12.1 and boost1.50.0
by Pravar 04 Sep '12

04 Sep '12

Hi All, I am getting compilation errors when I try to build my application code which includes some boost headers using IBM XL C/C++ compiler V12.1. ------------------------------------------------------------------------------------------------ "/opt/boost/include/boost/date_time/time_resolution_traits.hpp", line 71.21: 1540-0063 (S) The text "->" is unexpected. "/opt/boost/include/boost/date_time/time_resolution_traits.hpp", line 135.33: 1540-0040 (S) The text "<" is unexpected. "time_resolution_traits" may be undeclared or ambiguous. "/opt/boost/include/boost/date_time/time_resolution_traits.hpp", line 136.33: 1540-0040 (S) The text "<" is unexpected. "time_resolution_traits" may be undeclared or ambiguous. "/opt/boost/include/boost/date_time/time_resolution_traits.hpp", line 137.33: 1540-0040 (S) The text "<" is unexpected. "time_resolution_traits" may be undeclared or ambiguous. "/opt/boost/include/boost/date_time/posix_time/posix_time_config.hpp", line 40.44: 1540-0040 (S) The text "<" is unexpected. "date_time::time_resolution_traits" may be undeclared or ambiguous. ------------------------------------------------------------------------------------------------- These errors seems come due to the fact that this version of compiler is claimed to have more standard conformance than its predecessors. I confirmed from boost release notes of boost 1.50.0 that V12. of XL C/C++ supports this boost version. But still I encountered above errors. Should I use an older version of XL C/C++ compiler so that such errors can be avoided ? Does anybody encountered similar issues ? I am completely stuck at this point and would greatly appreciate any ideas to understand and resolve this. Thanks, Pravar DISCLAIMER: ----------------------------------------------------------------------------------------------------------------------- The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only. It shall not attach any liability on the originator or NECHCL or its affiliates. Any views or opinions presented in this email are solely those of the author and may not necessarily reflect the opinions of NECHCL or its affiliates. Any form of reproduction, dissemination, copying, disclosure, modification, distribution and / or publication of this message without the prior written consent of the author of this e-mail is strictly prohibited. If you have received this email in error please delete it and notify the sender immediately. . -----------------------------------------------------------------------------------------------------------------------

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