March 2005 - Boost-users - lists.boost.org

RE: [Boost-users] Boost.lambda
by Brian Braatz 30 Mar '05

30 Mar '05

Ah Kindred spirits. I asked a similar question awhile ago (like last year). I am sorry I was not able to find the original message. The answer I was given was that the & is the correct syntax per the CPP standard. What you are doing is taking the address of a memberfunction. What was confusing to me was that some compilers allow you to LEAVE OFF the & while others don't. The ones that do are trying to be helpful but are not conformant. ________________________________ From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Sean DeNigris Sent: Tuesday, March 29, 2005 7:31 PM To: boost-users(a)lists.boost.org Subject: [Boost-users] Boost.lambda Can anyone explain why the class member functions need their address taken when used in a boost::lambda::bind inside the class? e.g. vector<int> v; MyClass theClass; for_each(v.begin(), v.end(), bind(MyClass::DoSomething, &theClass, _1)); //The above compiles fine, but... class MyClass { public: void DoSomething(const int& i) { ... } void Go() { for_each(myInts.begin(), myInts.end(), /*--------------------->*/ bind(MyClass::DoSomething, this, _1)); } vector<int> myInts; }; The above code does not compile. The marked line needs to be: bind(&MyClass::DoSomething, this, _1)); Why? Thanks. - Sean

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Re: size of libboost_thread-gcc-mt.so
by Vladimir Prus 30 Mar '05

30 Mar '05

Amerio wrote: >>>> After compiling libboost_thread-gcc-mt.so on debian/gcc-2.95.4, >>>> this so weights 195kB > [...] >> Without read_write_mutex the size of gcc/release/shared build is 46K. >> With read_write_mutex the size is 136K. >> >> Wow, that's a difference! >> >> When I comment out explicit template instantiations in that source >> file, the library is becomes 76K. The comment says explicit >> instantination are needed to detect syntax errors in templates but >> those instantination bloat the library. > > Would there be any problem if I comment out the explicit instantations in > this file for production code ? > Are they in there *only* for syntax checking ??? I think that's the case. Adding #ifndef NDEBUG might be a reasonable solution. Note that if you use all of mutex types, you'll still get the code size penalty, but most likely you won't use all of them. > In this case, what about commiting a new rev in the cvs without this ? That's up to Boost.Thread maintainers. > Note : In my case, 100kB wasted is large enough to be an issue (running > low on free space, embedded system) I understand. - Volodya

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size of libboost_thread-gcc-mt.so
by Amerio 30 Mar '05

30 Mar '05

Hello, After compiling libboost_thread-gcc-mt.so on debian/gcc-2.95.4, this so weights 195kB, while libpthread weights only 100kB. Why such a huge difference ? Isn't boost::thread meant to be as lightweight as possible ? What about the raw inpact on runtime memory consumption compared to std pthreads ?

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Mailing list archive change and list downtime
by Beman Dawes 30 Mar '05

30 Mar '05

DongInn Kim, Jeff Squyres, and the other sysadmins at Indiana University are planning to switch all the Boost mailing list archives they host from MHonArc to Hypermail. They report "Hypermail seems to be much more stable, faster, and more efficient than MHonArc. We've been quite pleased with it, and have deployed it across most other lists on the listserver already (the boost lists were saved until last)." The old archives will still be available, and DongInn and Jeff have made various plans to minimize disruptions. All the listservers will be down during the transition, which is planned to start at 11 PM Saturday night (Eastern US time). Thanks to all the folks at IU for their help with Boost list hosting, --Beman

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Errors Compiling date_time Serialization Headers w/ Gcc on Linux
by Jalon, Arnon 30 Mar '05

30 Mar '05

Hi, I am new to the list. Appologies in advance if I'm posting something that's been already addressed, but I was unable to find anything related to it while searching the archives. I'm trying to use the date_time serialization headers in my application. I'm actually using the boost headers and libraries that came with the fedora core 3 linux distribution, and compiling with gcc 3.4.2. Including boost/date_time/time_serialize.hpp in my source gives me several compilation errors. I perused the time_serialize.hpp and greg_serialize.hpp headers and found places where the typename keyword was being used in front of class types that were simply qualified by namespace, as well functions where variables were used that weren't declared. I modified the headers to get it to compile, but would like to see if anyone else has been able to work around the problem in a less intrusive way? If need be I can post the patch files I created to a proper place. Below are the errors I was getting: g++ -g -I. -c parseAccessLog.cpp In file included from /usr/include/boost/date_time/posix_time/time_serialize.hpp :13, from logobject.hpp:11, from parseAccessLog.cpp:19: /usr/include/boost/date_time/gregorian/greg_serialize.hpp: In function `void boost::serialization::save(Archive&, const boost::gregorian::date_period&, unsigned int)': /usr/include/boost/date_time/gregorian/greg_serialize.hpp:150: error: no class template named `date' in `boost::gregorian' /usr/include/boost/date_time/gregorian/greg_serialize.hpp:150: error: invalid type in declaration before '=' token . . Repeated several times for similar condition through out greg_serialize.hpp . . /usr/include/boost/date_time/gregorian/greg_serialize.hpp: In function `void boost::serialization::load_construct_data(Archive&, boost::gregorian::nth_kday_of_month*, unsigned int)': /usr/include/boost/date_time/gregorian/greg_serialize.hpp:336: error: `pd' undeclared (first use this function) /usr/include/boost/date_time/gregorian/greg_serialize.hpp:336: error: (Each undeclared identifier is reported only once for each function it appears in.) . . Also repeated several times for similar condition . . In file included from logobject.hpp:11, from parseAccessLog.cpp:19: /usr/include/boost/date_time/posix_time/time_serialize.hpp: In function `void boost::serialization::save(Archive&, const boost::posix_time::time_period&, unsigned int)': /usr/include/boost/date_time/posix_time/time_serialize.hpp:131: error: no class template named `ptime' in `boost::posix_time' /usr/include/boost/date_time/posix_time/time_serialize.hpp:131: error: invalid type in declaration before '(' token . .

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Boost.lambda
by Sean DeNigris 30 Mar '05

30 Mar '05

Can anyone explain why the class member functions need their address taken when used in a boost::lambda::bind inside the class? e.g. vector<int> v; MyClass theClass; for_each(v.begin(), v.end(), bind(MyClass::DoSomething, &theClass, _1)); //The above compiles fine, but. class MyClass { public: void DoSomething(const int& i) { . } void Go() { for_each(myInts.begin(), myInts.end(), /*--------------------->*/ bind(MyClass::DoSomething, this, _1)); } vector<int> myInts; }; The above code does not compile. The marked line needs to be: bind(&MyClass::DoSomething, this, _1)); Why? Thanks. - Sean

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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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