- Boost-users - lists.boost.org

boost::read_write_mutex simple usage question.
by Gordon Smith 30 Mar '05

30 Mar '05

The following code seems to deadlock on the second (read) scoped lock (not what I would expect): boost::read_write_mutex mutex(boost::read_write_scheduling_policy::alternating_single_read); { boost::read_write_mutex::scoped_write_lock writeLock(mutex); } { boost::read_write_mutex::scoped_read_lock readLock(mutex); }

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Re: Loki vs. Boost
by Valery Aronov 29 Mar '05

29 Mar '05

Is there anything new to this old posting's question (2002) which was never answered? Is Loki going to be part of boost one day? Never? To what extent can they co-exist in one project? Thanks, Valery Hamlet wrote: > Hi, > I'm (desperately) looking for a serious comparative review of Loki vs. > Boost libraries. Although the differences are quite clear, > still it would be nice to see a serious comparison, > especially in the features that exists in both places, i.e. smart pointers, > small obj. allocator, type traits and template meta-programming. > Does anybody knows if there exists such a paper somewhere, or alternatively > have his own insights about the libraries? > > Thanks, > > Ariel

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boost::thread::join causes assertion (pthreads)
by Thorsten Froehlich 29 Mar '05

29 Mar '05

Hi, I noticed that when using thread::join and the thread has already completed, at least on Mac OS X using pthreads, pthread_join returns EINVAL, thus triggering the assertion res == 0. Is this intentional or a bug? Thorsten

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lexical_cast and infinity
by Patrick Mézard 29 Mar '05

29 Mar '05

The last line of the following program throws a bad_lexical_cast exception. The code is compiled with VC7.1. //********************************************************** #include <limits> #include <iostream> #include <boost/lexical_cast.hpp> int main(int argc, char* argv[]) { double d = std::numeric_limits<double>::infinity(); std::string s = boost::lexical_cast<std::string>(d); std::cout<<d<<", "<<s<<std::endl; //Throws bad_lexical_cast boost::lexical_cast<double>(s); } //********************************************************** The output is: "1.#INF, 1.#INF" Am I doing something wrong ? Patrick Mézard

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Boost.Jam
by Eyal Inbar 29 Mar '05

29 Mar '05

When I run bjam i get /lib/i686/libc.so.6: version 'GLIBS_2.3' not found (required by bjam) What i need to do? eyal

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RE: [Boost-users] compile error
by Eyal Inbar 29 Mar '05

29 Mar '05

Thank It's in CPPFLAGS. but i found it after i look into the Makefile and try some arguments. Now i found that in /root/.bash_profile i set CXX to be my compiler command export CXX="g++ -ftemplate-depth-31" and it works with all the projects Eyal -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org]On Behalf Of Malte Starostik Sent: Monday, March 28, 2005 4:30 PM To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] compile error Eyal Inbar schrieb: [how to add -ftemplate-depth-NN] > Thanks > But how and where can i changed the flag in g++ ? I don't know exactly where it is in KDevelop, but usually in IDEs, somewhere in the project options you can add/change compilation flags. Look around in the options, check the manual. For often used flags there may be predefined options to check, for things like the template depth you probably have to enter -ftemplate-depth-NN where NN is the desired value manually in some "extended options" or similar field. HTH, Malte _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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delete shared_ptr object???
by Dan Bikel 29 Mar '05

29 Mar '05

Rather disturbingly, the following code compiles (at least, with g++-3.3.2): #include "boost/shared_ptr.hpp" using namespace boost; class X {}; int main() { const shared_ptr<X> y; delete y; } Normally, when you compile code with delete applied to a non-pointer type, you get a compile-time error. What's going on here? TIA, Dan.

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regex expressions in boost::regex vs python, how to get the answer from boost
by Alexis H. Rivera-Rios 29 Mar '05

29 Mar '05

Hi, I'm playing around with the boost::regex library and I want to match two tokens from a filename. For example files with the following format: myname_123.dat I want to be able to determine the string and number separated by the underscore. So the result of my match should be "myname", and 123. In python, I can do it like this: import re >>> x = 'myclass_123.dat' >>> result = re.match(r'(\w+)_(\d+)\.dat$', x) >>> result.group(1) 'myclass' >>> result.group(2) '123' I'm having problems getting the same result in C++. This is the sample program: int main(int argc, const char** argv) { boost::regex expression("(\\w+)_(\\d+)\\.dat$"); std::string filename(argv[1]); boost::cmatch what; if(boost::regex_search(filename.c_str(), what, expression)) { for (int i=0;i<what.size();++i) { std::cout << what[i].first << " " << what[i].second << std::endl; } } return 0; } The output of this program is: > openmp3 alexis_1023.dat alexis_1023.dat alexis_1023.dat _1023.dat 1023.dat .dat How do I get my groups "alexis", 123 as in Python? Thanks, Alexis Programming Tutorial: In Python: To do this, do this In Perl: To do this, do this or this or this or this... In C: To do this, do this, but be careful In C++: To do this, do this, but don't do this, be careful of this, watch out for this, and whatever you do, don't do this __________________________________ Do you Yahoo!? Yahoo! Small Business - Try our new resources site! http://smallbusiness.yahoo.com/resources/

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Any interest in postconstruction/predestruction facility?
by Malte Starostik 29 Mar '05

29 Mar '05

Hi, I'm using a wrapper class to automate postconstruction and predestruction. A preliminarily boostified version (added licence header, changed namespace to boost) is available at http://malte.homeip.net/~malte/prepost/ prepost.hpp[.html] contains the library The file example.cpp[.html] shows an example usage: The class thread_base starts a new thread in it's post_construction() member function which runs the virtual run() member function in the new thread. Since run() is to be overridden by a derived class, this cannot be done by the ctor. Similarly, the thread is joined in the pre_destruction() member function, as the dtor would be too late since the derived class's instance must not have been destructed before the thread finished. The basic usage is to derive a class X from post_constructed and/or pre_destructed according to which facilities are needed. Then, instead of instantiating X directly, user code instantiates prepost_wrapper< X >. Direct instantiation of X is prevented by the presence of pure virtuals in the classes post_constructed and pre_destructed. As in most if not all cases, X will be polymorphic anyway, I considered the benefit of prevented circumvention of the mechanism worth the two additional entries in the vtable. Is there any interest in having this facility? BTW, the name prepost_wrapper is definately the result of my lacking imagination. Any suggestions appreciated ;-) Outstanding issues: * maybe prepost_wrapper should prevent being used as an intermediate class * the forwarding ctors of prepost_wrapper are problematic if one or more of the base class's ctors are explicit * the hardcoded maximum number of ctor args should be configurable * anything else I didn't think of? BTW, I tried to have the default ctor generated by the BOOST_PP_REPEAT macro as well, but failed miserably to find a way to omit template<> if n is 0. Some help in this area is appreciated as well. Cheers, Malte

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BGL: subgraph and bundled properties
by Wintermantel, Marc 28 Mar '05

28 Mar '05

Hello, I would like to create a graph-tree structure (subgraph concept) with bundled properties. The creation of the graphs works fine. However the interface for bundled graphs seems not to be implanted in subgraph. Is this right? Is it just forgotten in subgraphs or does the concept of bundled properties and subgraph not work together. Cheers, Marc

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