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Boost.Thread: timed_join, interruption/cancellation and c++0x
by Daniel Neuberger 01 Mar '11

01 Mar '11

Am I understanding correctly that there's no plan to support timed_join and interruption/cancellation in c++0x. If so, will Boost.Thread continue to support them? Also, will Boost.Thread be adding support for variadic templates sometime soon? In short we want to use threads with variadic templates, but need support for timed_join and interruption points. Thanks, - Daniel

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boost::ptime on the wire....
by david.weber＠l-3com.com 01 Mar '11

01 Mar '11

I've got a case, where I need to transmit a timestamp across the wire, in a cross-platform manner. My first choice was boost::ptime, but I cannot seem to find a way to serialize a timestamp in a nice compact manner (i.e.: Two UINT64's, or four, or whatever). This is actually pretty important, as I need to define the ICD between the sender and recipient. Am I just overlooking something slick? Thanks --dw

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[python] intercepting uncaught exceptions
by Gennadiy Rozental 01 Mar '11

01 Mar '11

Hi, I am using Boost.Python quite extensively (even stretching it to the limit in some cases). Now I cave this problem: Is there any way to intercept uncaught exception in embedded Python code? I need to add some information to an exception/traceback in this case. I have full control over environment before embedded code is executed. I thought I'll be able to use sys.excepthook, but it does not seem to be invoked. Alternatively I'd can live if I can somehow retrieve the context of failed call (global/local dict?) in boost::python::error_already_set handler. Please advise, Gennadiy

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[MSM] test if state machine is in a given state / const get_state
by Jan Vogelgesang 01 Mar '11

01 Mar '11

Hello all, i am working with the Boost 1.45 Meta State Machine, using both orthogonal regions and submachines. Overall, i am very happy with this library. But i am looking for a nice way to check if a state machine (e.g. instance mAvail of class AvailFSM) is in a given state, for example i would like to write something like this: assert(isInState(mAvail, AvailFSM::UpstreamAvailable())); I didn't find something like "isInState" provided by the MSM library, so i came up with the following implementation: template <class FSM, class StateType> bool isInState(const FSM& p, const StateType& s) { int stateId = boost::msm::back::get_state_id<typename FSM::stt,StateType>::value; for (int i=0; i < FSM::nr_regions::value; ++i) { if(p.current_state()[i] == stateId) { return true; } } return false; } This works well for simple state machines and orthogonal regions, but not for submachines. Does any one knows a way to extend the above code to work with submachines? Lets say the state "AvailFSM::UpstreamAvailable" from above is in fact a submachine, having the state "Primary" amongst others. It would be nice to have the following working: assert(isInState(mAvail, AvailFSM::UpstreamAvailable::Primary())); Currently i am using the following workaround: assert(isInState(mAvail, AvailFSM::UpstreamAvailable())); assert(isInState(mAvail.get_state<AvailFSM::UpstreamAvailable&>(), AvailFSM::UpstreamAvailable::Primary())); I consider this solution ugly not only because of its lengthiness, but also because "get_state" isn't a const function. Unfortunately i'am not deep enough into the template magic to tell if a const implementation of "get_state" is possible. Can anyone help me out ? So, to sum up, i have two questions: 1) How to implement something like "isInState" that even works on submachines, if possible ? 2) Is a const version of "get_state" possible ? And how? best regards, jan

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boost::asio from C++ Forms App in VS 2010
by Alan Vella 01 Mar '11

01 Mar '11

Hi all, I'm trying to port a C++ project from gcc (on MinGW) to Visual Studio 2010 inside a Visual C++ Windows Forms application. The code was originally written on a Windows XP 32-bit machine. Now it is being ported into a Windows 7 32-bit machine. This project uses quite a few boost libraries, including the boost::asio library. When I try to compile the code in VS2010 I get the following errors: 1> Please define _WIN32_WINNT or _WIN32_WINDOWS appropriately. For example: 1> - add -D_WIN32_WINNT=0x0501 to the compiler command line; or 1> - add _WIN32_WINNT=0x0501 to your project's Preprocessor Definitions. 1> Assuming _WIN32_WINNT=0x0501 (i.e. Windows XP target). 1>C:\Program Files\boost\boost_1_44\boost/asio/detail/impl/win_thread.ipp(52): error C2664: 'QueueUserAPC' : cannot convert parameter 1 from 'void (__stdcall *)(ULONG_PTR)' to 'PAPCFUNC' 1> Address of a function yields __clrcall calling convention in /clr:pure and /clr:safe; consider using __clrcall in target type 1>C:\Program Files\boost\boost_1_44\boost/asio/detail/impl/win_thread.ipp(82): error C2664: '_beginthreadex' : cannot convert parameter 3 from 'unsigned int (__stdcall *)(void *)' to 'unsigned int (__stdcall *)(void *)' 1> Address of a function yields __clrcall calling convention in /clr:pure and /clr:safe; consider using __clrcall in target type 1>C:\Program Files\boost\boost_1_44\boost/asio/detail/win_thread.hpp(31): error C3641: 'boost::asio::detail::win_thread_function' : invalid calling convention '__stdcall ' for function compiled with /clr:pure or /clr:safe 1>C:\Program Files\boost\boost_1_44\boost/asio/detail/win_thread.hpp(36): error C3641: 'boost::asio::detail::apc_function' : invalid calling convention '__stdcall ' for function compiled with /clr:pure or /clr:safe 1>C:\Program Files\boost\boost_1_44\boost/asio/detail/win_fenced_block.hpp(35): error C3862: 'boost::asio::detail::win_fenced_block::win_fenced_block': cannot compile an unmanaged function with /clr:pure or /clr:safe 1> Inline native assembly not supported in managed code 1>C:\Program Files\boost\boost_1_44\boost/asio/detail/win_fenced_block.hpp(35): error C3645: 'boost::asio::detail::win_fenced_block::win_fenced_block' : __clrcall cannot be used on functions compiled to native code 1>C:\Program Files\boost\boost_1_44\boost/asio/detail/win_fenced_block.hpp(54): error C3862: 'boost::asio::detail::win_fenced_block::~win_fenced_block': cannot compile an unmanaged function with /clr:pure or /clr:safe 1> Inline native assembly not supported in managed code 1>C:\Program Files\boost\boost_1_44\boost/asio/detail/win_fenced_block.hpp(54): error C3645: 'boost::asio::detail::win_fenced_block::~win_fenced_block' : __clrcall cannot be used on functions compiled to native code 1> 1>Build FAILED. Any help would be much appreciated. Cheers, Alan Vella. _______________________________________________________ Unlimited Disk, Data Transfer, PHP/MySQL Domain Hosting http://www.doteasy.com

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Boost.Unordered: custom hasher
by gast128 01 Mar '11

01 Mar '11

Hello all, for using the unordered_set with a user defined class one can define a custom hasher. There seems to be the following options: - overide boost::hash_value - write ur own custom hash functor Both options have then an external hash function. I was more thinking about using a member function as hasher (e.g. like GetHashCode). A supporting class would be then: template <typename T, typename RetType, RetType (T::*pmf)() const> struct unary_function_mf : std::unary_function<T, RetType> { RetType operator()(const T& r) const { return (r.*pmf)(); } }; which makes specifying an unordered_set easier: boost::unordered_set<Person, unary_function_mf<Person, size_t, &Person::GetHashCode> > uset2; My questions: 1) is this correct c++ 2) does something similar exist in Boost (Boost.Function and Bind doesn't seem to support his) 3) is there an advantage of using a free function over functor? The free function has at least one advantage, that it also works with the std::pair hasher.

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[phoenix] V2, V3 and the amount of memory needed by the compiler to just include them
by Mathieu Champlon 01 Mar '11

01 Mar '11

Hello, Phoenix is an outstanding component, I have no doubt about that. However I have had some mixed results for my use case using V2 and now switching to V3. I'm writing a (header only/template) library which uses Boost.Phoenix internally. By nature this library (a mock object library) often ends up in precompiled headers because it's convenient to have it de facto included for whole (unit test) applications. By default Microsoft Visual Studio allocates a certain amount of memory for compiling a precompiled header, and if it actually needs more then it fails to compile. For instance with only : #include <boost/phoenix/phoenix.hpp> Here is the error message with vc80 : ...boost/fusion/container/vector/vector10.hpp(52) : error C3859: virtual memory range for PCH exceeded; please recompile with a command line option of '-Zm160' or greater ...boost/fusion/container/vector/vector10.hpp(52) : fatal error C1076: compiler limit : internal heap limit reached; use /Zm to specify a higher limit The location of the error is irrelevant, the value suggested by the compiler is what matters. Here it suggests to add /Zm160 to the command line. This is pretty huge, the default is actually /Zm100, and I'd say "big" Boost libraries are around 50. /Zm100 now means 75MB since vc90 instead of 50MB for vc80, which helps a bit, but still... Here is a quick survey I did with vc80, using a /Zm1 to trigger an error every time. The number on the right is the required /Zm value for including only the file on the left. boost/phoenix/phoenix.hpp 160 "equivalent of content of boost/phoenix/phoenix.hpp for Phoenix 2" 107 boost/phoenix/core/nothing.hpp 61 boost/spirit/home/phoenix/core/nothing.hpp 52 boost/phoenix/statement/throw.hpp 62 boost/spirit/home/phoenix/statement/throw.hpp 54 boost/phoenix/bind.hpp 43 boost/spirit/home/phoenix/bind.hpp 56 boost/bind.hpp 17 boost/lambda/bind.hpp 27 boost/lambda/lambda.hpp 30 boost/function.hpp 36 boost/function_types/function_type.hpp 31 boost/test/auto_unit_test.hpp 41 boost/concept_check.hpp 16 boost/type_traits/remove_reference.hpp 12 boost/proto/proto.hpp 55 boost/proto/domain.hpp 20 Note that an empty pch requires /Zm11 Now extracting only the includes from Phoenix to other Boost libraries using : grep -rh "include <b" . | sort -u And removing all boost/phoenix, the result is /Zm56 for V3 and /Zm65 for V2. So V3 reduces the code of Phoenix itself but now uses (a lot) more of other Boost libraries, which incidentally is consistent with the main target of V3 switching to Boost.Proto Of course the resulting amount of memory required for my library is not the sum of the memory required for each included library taken separately (mostly because they re-use each others). And furthermore I can mostly work around the issue by using only phoenix::bind and rewrite some of the missing bits (for instance phoenix::throw_ and phoenix::nothing) But even then and with carefully selecting the includes, it ends up pretty close to the default /Zm100. This means that if the users of my library add a couple more libraries to their pch (Boost.Test comes to mind), they will most certainly go over the limit. All right, after boggling a bit, they will add a bigger /Zm and forget about it for a while, until they upgrade either my library or Boost. Suddenly a lot of their test applications fail to compile because instead of some /Zm112 it now requires /Zm113, and they will need to go over all their projects and update them... For having this happening at my day job on a regular basis, I can attest first hand it is indeed annoying ! I started by saying I have had mixed results using Phoenix, this is because on one hand I resorted to rewriting what I needed using only phoenix::bind and I fear for the future usability of Phoenix, but on the other hand switching to V3 boost/phoenix/bind.hpp actually saves some memory compared to V2 boost/spirit/home/phoenix/bind.hpp ! Regards, MAT.

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[Units] Variant runtime analysis
by Samuel Debionne 01 Mar '11

01 Mar '11

Hello all, My use case is the following : I have a function that returns quantities of different units depending on its input parameters (different derivatives). I could split the function in two parts that returns one unit only, but that would move the problem to an other place in my code. Is there any way to handle this, without breaking the dimensional analysis ? I have been playing with things like : quantity<variant<force, length, energy> > but it doesn't seems to go anywhere... Samuel

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Is is possible to place multi_arrays in maps???
by Ramon F. Herrera 01 Mar '11

01 Mar '11

I need a set of multi_arrays, and so far it seems that I can only have one of them (with the same name) at a time. What I need is a loop where the original multi_array is resized, filled and the current copy saved in a map. Is that possible? TIA, -RFH

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boost::range : comparison operators
by er 01 Mar '11

01 Mar '11

Hello, I'm interested in make_iterator_range( container ); defined in http://svn.boost.org/svn/boost/trunk/boost/range/iterator_range_core.hpp in order to adapt container to have comparison operators. While, template< class IteratorT, class ForwardRange > inline bool operator<( const ForwardRange& l, const iterator_range<IteratorT>& r ) is defined, operator>, for example, isn't. Is there a functionality that provides all operators? Thanks.

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