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[Containers] Marshalling deques
by Brian Wood 26 Aug '11

26 Aug '11

There's a thread here -- http://groups.google.com/group/comp.lang.c++/browse_thread/thread/0a6a19f83… that I'd like to mention. Does the deque in the Containers library have support for accessing the chunks it uses? Would you be willing to add a function that gives that? Tia. Shalom, Brian Wood Ebenezer Enterprises http://webEbenezer.net

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asio tcp::resolver, service resolution
by Lloyd 26 Aug '11

26 Aug '11

Hi, In documentation I saw that using tcp::resolver::query constructor it is possible to resolve domain.name as well as service name, as shown in the following code fragment. boost::asio::io_service ios; boost::asio::ip::tcp::resolver resolver(ios); boost::asio::ip::tcp::resolver::query query("mydomain.com","myservice"); Here 'myservice' is not a well known service (port number). For resolving 'myservice' where should I add the port number? in my domain name server's (BIND) /etc/services file or in my local systems services file? Or is it 'really' possible to resolve a service name? Thanks, Lloyd

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accumulator: serialization support
by Neal Becker 26 Aug '11

26 Aug '11

I have typedef accumulator_set<el_t,stats<tag::mean,tag::abs_sqr> > accum_t; How can I add serialization?

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[qi][lambda] Get wrong reaction of the qi::rule if I use lambda for the action
by boost_mailinglist＠gmx.de 26 Aug '11

26 Aug '11

Hello, if I execute the following example, I get the following output "The bad one The good one a" but I only expected "The good one a". Why does it happens? Boost 1.47.0 was used. #include <boost/config/warning_disable.hpp> #include <boost/spirit/include/qi.hpp> #include <boost/lambda/lambda.hpp> #include <iostream> int main() { using boost::spirit::qi::char_; using boost::spirit::qi::parse; char const *first = "{a}", *last = first + std::strlen(first); parse(first, last, '{' >> char_("a")[std::cout << "The good one " << boost::lambda::_1 << '\n'] | char_("b")[std::cout << "The bad one " << boost::lambda::_1 << '\n'] >> '}'); return 0; }

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[boost::polygon::transform.hpp] Concatenation of transformations fails.
by Dimitris Dakopoulos 26 Aug '11

26 Aug '11

Hello to all, I want to apply to geometrical transformations (in this case translations) on a point. Point3D trans1(1,0,0); Point3D trans2(2,0,0); Point2D p(100,100); gtl::transformation<int> T1( trans1 ); gtl::transformation<int> T2( trans2 ); gtl::transform( p, T1 ); gtl::transform( p, T2 ); --- ... and the point's coordinates are (97,100) as expected. --- When I try to concatenate the transformations: Point3D trans1(1,0,0); Point3D trans2(2,0,0); Point2D p(100,100); gtl::transformation<int> T1( trans1 ); gtl::transformation<int> T2( trans2 ); gtl::transform( p, T1 + T2 ); --- ... and I get random numbers. I checked the boost/polygon/detail/transform_detail.hpp template <typename coordinate_type> inline const transformation<coordinate_type>& transformation<coordinate_type>::operator+=(const transformation<coordinate_type>& tr){ //apply the inverse transformation of this to the translation point of that //and convolve it with this translation point coordinate_type x, y, z; transformation<coordinate_type> inv = inverse(); inv.transform(x, y, z); p_.set(HORIZONTAL, p_.get(HORIZONTAL) + x); p_.set(VERTICAL, p_.get(VERTICAL) + y); p_.set(PROXIMAL, p_.get(PROXIMAL) + z); //concatenate axis transforms atr_ += tr.atr_; return *this; } ... and I noticed that the coordinate_type x, y, z; is not initialized and then the transformation is applied: inv.transform(x,y,z); which of course results to something random. Any ideas? Thank you for checking. Dimitris

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[serialization] The famous non-const value trap
by cc caprani 26 Aug '11

26 Aug '11

Hi Boosters, I had the compile time warning discussed here ( http://boost.2283326.n4.nabble.com/Serialization-C4308-warning-with-MSVC9-t…) that Robert is probably fed up discussing. I've read for months, but didn't want to const_cast my object (or is it ok sometimes?). However, making my destructor virtual removed the warning. Here's my question: why does making the object destructor virtual remove the warning, effectively making my object instances const? And the section on this trap from the Rationale section of the Serialization documentation is not in the1.47 version (howcome?) but can be found in previous version here: http://www.boost.org/doc/libs/1_39_0/libs/serialization/doc/rationale.html#… Oh, and please forgive me if the answer is *obvious* - just an intermediate programmer. Colin

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Subject: Re: [Containers] Marshalling deques
by Brian Wood 26 Aug '11

26 Aug '11

Michael Goldshteyn: > I think that having a ?configurable? deque class template > is one of the best things that could be offered by a boost > Containers library. I have always wondered why noone > wrote a version of the deque class template that allowed > the configuration of such things as the page / block size, > rather than have it be determined by a compile time > formula based on the size of the data type being stored. > It would seem to me that the page / block size is one of > the more critical pieces affecting the size / speed > tradeoffs in a deque?s performance when there are many > insertions taking place. The thread I mentioned has a link to a segmented_array container which may be of interest. I agree that what you suggest would be an improvement. Shalom, Brian Wood Ebenezer Enterprises http://webEbenezer.net <http://webebenezer.net/>

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[filesystem] posix path on cygwin disappeared - how to make it work?
by Frédéric Bron 25 Aug '11

25 Aug '11

How can I use the posix path on cygwin? I am trying to upgrade from 1.43 but macros BOOST_POSIX_API and BOOST_POSIX_PATH are now deprecated. Why forcing WINDOWS_API while it worked well before? Regards, Frédéric

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boost::mutex::scoped_lock fails with res = 22 (EINVAL)
by Andrej van der Zee 25 Aug '11

25 Aug '11

Hi, I am trying to understand why the acquiring of a lock fails on error code 22 (EINVAL). After Googling I find one of two causes: 1) The mutex was created with the protocol attribute having the value PTHREAD_PRIO_PROTECT and the calling thread's priority is higher than the mutex's current priority ceiling. The mutex is created by the main-thread and the lock is acquired by a thread from a boost::thread_group. But in many cases the lock is acquired without error, so I guess this is not the cause. 2) The value specified by mutex does not refer to an initialized mutex object. The mutex is default constructed by boost::mutex's constructor so I expect it to be initialized properly. Both causes *seem* not to apply to my case. What am I missing here? I am using boost 1.46.1 on Ubuntu amd64. Cheers, Andrej

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Re: [Boost-users] [type traits] Extension to operator operatordetection -> choose your preferred naming
by Alex Perry 25 Aug '11

25 Aug '11

on Tue Aug 23 2011, Fr?d?ric Bron <frederic.bron-AT-m4x.org> wrote: > We have come to three proposed lists of names (A, B and C): > https://svn.boost.org/trac/boost/wiki/GuideLines/Naming/OperatorTraitN > ames I have included the corresponding names of standard keywords, > standard function objects from <functional>, boost Proto and boost > Operators. Another vote for C (though having done nothing on this not sure my vote really counts for anything) - only issue I have with C is :- has_negate surely has_unary_minus needs to be there as an alias for this at the very least. Alex

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