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Visitor Pattern Implementation
by Rodrigo Madera 07 Nov '08

07 Nov '08

Dear community, Is there any implementation/helper/inspiration/or-alike in Boost for the Visitor Pattern? I know of Boost Signals, which is awesome, but (as stated in the FAQ) it's not Thread-safe (yikes!). Thank you for your kind input, Rodrigo

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[Regex] 1.37.0: Truncation warning under Windows
by Peter Klotz 07 Nov '08

07 Nov '08

MSCV8 gives this warning when compiling Boost.Regex 1.37.0 under Windows x86 (32 Bit): libs\regex\src\..\src\cregex.cpp(563) : warning C4309: 'static_cast' : truncation of constant value The code that produces the warning: #ifdef BOOST_HAS_LONG_LONG const std::size_t RegEx::npos = static_cast<std::size_t>(~0ULL); #else const std::size_t RegEx::npos = static_cast<std::size_t>(~0UL); #endif In Windows x86 sizeof(unsigned long long int) is 8, sizeof(std::size_t) is 4 and BOOST_HAS_LONG_LONG is defined. Therefore "~0ULL" is truncated from 8 to 4 bytes. Maybe a better trigger would be the architecture (32 Bit or 64 Bit) since in all environments I know sizeof(std::size_t) equals the architecture. Regards, Peter.

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[bjam] Generated path approaches 255 character OS limit
by Peter Klotz 07 Nov '08

07 Nov '08

When compiling Boost 1.37.0 using this bjam command line under Windows I obtained the error message below: bjam -q -sNO_COMPRESSION=1 --build-type=complete --without-graph --without-math --without-mpi --without-python --without-serialization --without-signals --without-wave --toolset=msvc-8.0 architecture=x86 address-model=64 failed to write output file 'bin.v2\libs\test\build\msvc-8.0\debug\address-model-64\architecture-x86\asynch-exceptions-on\link-static\runtime-link-static\threading-multi\libboost_prg_exec_monitor-vc80-mt-sgd-1_37.lib.rsp'! Obviously the path I started from (70 characters) combined with the bjam generated path (192 characters) exceeds the OS limit of 255 characters per filename. Does the bjam generated path really have to be this long? Can I shorten it somehow? If future versions of bjam encode even more information into the generated path it may not be possible to build Boost even when building in directory C:\Boost. Regards, Peter.

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Re: [Boost-users] Boost-users] question about threading library
by Tan, Tom (Shanghai) 07 Nov '08

07 Nov '08

Please read this link by the author of boost.thread: http://www.devx.com/SpecialReports/Article/38883/1954?pf=true, He also has a personal blog worth reading: http://www.justsoftwaresolutions.co.uk/ concerning your specific questions: 1. boost::mutex::scoped_lock is just a typedef of unique_lock<mutex> inside mutex. With this kind of typedef, you'll be able to use the same type scoped_lock for other kind of mutex( For example Timed_mutex ) by changing the mutex type only. There IS the definition on this page: http://www.boost.org/doc/libs/1_37_0/doc/html/thread/synchronization.htm l#thread.synchronization.mutex_types 2. " std::lock_guard is deliberately basic and can only be used as shown. On the other hand, std::unique_lock allows for deferred locking, trying to lock, trying to lock with a timeout, and unlocking before the object is destroyed. "(copied from the first link above) HTH. >From: "Robert Ramey" <ramey(a)rrsd.com> >Subject: [Boost-users] question about threading library > >I want to use the boost threading library in an application. > >Looking through the documentation, I have a questions. >a) in the examples I find "boost::mutex::scoped_lock" but >I don't find this in the documentation. It looks like this >is called "lock_guard". What should I be doing here. >b) Its not clear to me how unique_lock(Lockable l) >is different than using lock_gard(..) or scoped_lock. >Robert Ramey **************************************

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[random] streamable state of normal_distribution to ostream not accurate
by Oei, YC 07 Nov '08

07 Nov '08

Dear list members, I'm using the Boost Random Number Library, and am now trying to store the state of an instance of normal_distribution by means of its << operator. It doesn't however seem to work: three of its data members are definitely not outputting properly on my system. I can reproduce the problem with this test file: ----- #include <boost/random/mersenne_twister.hpp> #include <boost/random/variate_generator.hpp> #include <boost/random/normal_distribution.hpp> #include <iomanip> #include <iostream> #include <limits> using namespace boost; using namespace std; int main() { mt19937 rng; normal_distribution<> gauss; variate_generator<mt19937&, normal_distribution<> > var(rng, gauss); cerr << setprecision(numeric_limits<double>::digits10 * 2); for (size_t i = 0; i != 5; ++i) { cerr << var() << endl; //prints a random number cerr << gauss << endl; //dumps object internal state } //for } //main ----- which, on Ubuntu 8.04 amd64 (gcc 4.2.4, boost 1.34.1) produces this output: 0.21343601372288967255030911474 0 1 0 6.95335189373114898041666608493e-310 6.9533518937319394854500120794e-310 -0.495580282118778303601658308253 0 1 0 6.95335189373114898041666608493e-310 6.9533518937319394854500120794e-310 1.57537639010992913668474102451 0 1 0 6.95335189373114898041666608493e-310 6.9533518937319394854500120794e-310 -1.05920392793252360341682560829 0 1 0 6.95335189373114898041666608493e-310 6.9533518937319394854500120794e-310 1.83926543714107570970384131215 0 1 0 6.95335189373114898041666608493e-310 6.9533518937319394854500120794e-310 ...and I get similar output on an OpenSuse 10.2 x86_64 system (gcc 4.1.2, boost 1.33.1). If I understand the code in boost/random/normal_distribution.hpp correctly, the third member in the stream represents _valid and should alternate between 0 and 1, and the last two values should definitely not stay the same for five iterations. Can you tell me if I'm doing anything wrong? (And, slightly offtopic, what should I set the stream-precision at to ensure exact reloading of the floating point data?) Many thanks for reading and thinking about this, Yung-Chin Oei

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#include <boost/asio.hpp> makes installshield's "Extract COM Interface" get bad winsock2 registry settings
by Kevin McMahon 07 Nov '08

07 Nov '08

All I have to do is #include <boost/asio.hpp>. I tried boost 1.35 and boost 1.37 with Visual Studio 2008. If it is included, InstallShield's RegSpyUI (or it's "Extract COM Interface" step) gets bad Winsock2 registry settings. When InstallShield applies those settings, it screws up the machine. Most notably, DNS is disabled. The registry settings that appear are: HKEY_LOCAL_MACHINE\ System\ CurrentControlSet\ Services\ WinSock2\ Parameters\ WinSock_Registry_version==>2.0 NameSpace_Catalog5\ Num_Catalog_Entries==>0 Serial_Access_Num==>1 Catalog_Entries\ Protocol_Catalog9\ Num_Catalog_Entries==>0 Next_Catalog_Entry_ID==>-23 Serial_Access_Num==>1 Catalog_Entries\ I don't know where they come from. I'm still trying to figure it out. If anyone has any advice, I'd be grateful. Thanks, Kevin McMahon kevin(a)pando.com Kevin McMahon kevinmcm(a)alum.mit.edu

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compiler support question
by Brian Nantz 06 Nov '08

06 Nov '08

I have seen the list of compilers that boost officially supports (http://www.boost.org/boost-build2/doc/html/bbv2/reference/tools.html) But I am wondering if anyone has tried boost on CAD-UL? I need to support this compiler on Linux for an embedded device. Brian

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Multiple compiler & platform support.
by Brian Nantz 06 Nov '08

06 Nov '08

One of the things that drew me to use boost is that is supports so many compilers and platforms that can be mixed and matched. I am creating a library on top of boost and Arabica. I want this library I am creating to support all the compilers and platforms that boost does. What is the easiest way to do this? Do I have to duplicate much of the config and decl stuff? Has anyone done this and have some advice? brian

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Re: [Boost-users] [Multi-index] hash_unique memory consumption vs std::map
by JOAQUIN M. LOPEZ MUÑOZ 06 Nov '08

06 Nov '08

________________________________________ De: boost-users-bounces(a)lists.boost.org [boost-users-bounces(a)lists.boost.org] En nombre de Michael Fawcett [michael.fawcett(a)gmail.com] Enviado el: jueves, 06 de noviembre de 2008 22:34 Para: boost-users(a)lists.boost.org Asunto: Re: [Boost-users] [Multi-index] hash_unique memory consumption vsstd::map > Do you know of a better way to track memory usage in Windows? Task > Manager is obviously not up to the task, VTune reports it on a > system-wide basis, not per process, and _Crt* functions require > modifying your code. Use an instrumented allocator, like count_allocator in http://tinyurl.com/66xhv7 . It is an intrusive, but very precise method. Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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[Multi-index] hash_unique memory consumption vs std::map
by Michael Fawcett 06 Nov '08

06 Nov '08

In my application I need to load millions of vertices into a graph. I'm using BGL for this. Each edge has around 20-30 attributes associated with it and each attribute has a unique ID (not necessarily sequential or 0-based). I'm currently using this multi_index_container for the attributes: typedef detail::mutable_pair<long, _variant_t> id_attribute_pair_type; typedef boost::multi_index_container < id_attribute_pair_type, boost::multi_index::indexed_by < boost::multi_index::hashed_unique<boost::multi_index::member<id_attribute_pair_type, long, &id_attribute_pair_type::first> > > > map_type; which emulates: typedef std::map<long, _variant_t> map_type; If I check memory consumption after loading the graph using multi_index I'm at 190MB. Using std::map it's at 124MB. I realize this is because std::map is perfectly sized and a hashmap will grow in chunks, but is there a way I can reserve a size ahead of time since I know exactly how many attributes there will be? My graph loading performance does not seem to change between multi_index and map, however subsequent search operations (shortest_path, etc) seem to favor multi_index. Thanks for such a great library. I've used it in many projects. --Michael Fawcett

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