November 2005 - Boost-users

Re: [Boost-users] [Multi-Index] composite_key problems
by JOAQUIN LOPEZ MU?Z 01 Nov '05

01 Nov '05

----- Mensaje original ----- De: Andreas Volz <lists(a)brachttal.net> Fecha: Martes, Noviembre 1, 2005 0:28 am Asunto: Re: [Boost-users] [Multi-Index] composite_key problems > I got it working! Perhaps I've some more questions, but for now I > couldcontinue my work. Excellent! Good luck with your project. > > Did someone create a SQL language wrapper around multi_index? I think > this could be a very great feature. People that know SQL could really > easy use it without learning too much other stuff. There's currently a very active debate going on with respect to the merits of two libraries which offer a more SQL-friendly interface to handle multi-index data structures (none of them is actually SQL compatible, though.) Google for RML site:boost.org to get some links to the discussion. RML site is http://visula.org/relational/ while RTL stuff can be found at http://boost-consulting.com/vault/index.php? &direction=0&order=&directory=RTL > I thought about > using a lightweight SQL lib (e.g. sqlite) before I found multi_index. > But I don't save my data into a file, so multi_index fits perfect. > You can also save/load multi_index_containers contents to/from a file via Boost.Serialization. Check http://boost.org/libs/multi_index/doc/advanced_topics.html#serializatio n Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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Visual C++ 2005 (8.0) support
by Ovanes Markarian 01 Nov '05

01 Nov '05

Hi all, did someone test boost 1.33 with Visual C++ 2005(8.0)? I am wondering how I can compile the library using jam. Should I use VC++ 7.1 option? Another question. I derived an iterator from the iterator_facade template. As I have recently found out VC++ 8.0 did not support friend template classes, e.g. template<class ....> class my_type { template <class> friend class my_type; ... }; This will not work in VC++ 8.0. Did you know about this issue? Should this be filed as a bug at MS? With Kind Regards, Ovanes Markarian

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Re: [Boost-users] problem with multi_index_container -> find
by JOAQUIN LOPEZ MU?Z 01 Nov '05

01 Nov '05

Hi Oliver, ----- Mensaje original ----- De: Oliver.Kowalke(a)infineon.com Fecha: Martes, Noviembre 1, 2005 10:38 am Asunto: [Boost-users] problem with multi_index_container -> find > Hello, > I don't understand why this code doesn't compile (gcc-3.3.1) '... > id_index.find( id) ...' ? > Regards, > Oliver [...] > phonebook::iterator itr = id_index.find( id); // <<== doesn't id_index.find() returns a phonebook::nth_index_iterator<1>::type. phonebook::iterator is shorthand for phonebook::nth_index_iterator<0>::type, a different type. The following should work phonebook::nth_index_iterator<1>::type itr = id_index.find(id); or alternatively phonebook::nth_index<1>::type::iterator itr = id_index.find(id); Hope this helps, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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How to build Boost for Cygwin (asked the noob)
by Olumide 01 Nov '05

01 Nov '05

Hi - Would someone please give me some (SIMPLE) pointers on how to build Boost for Cygwin. Thanks, - Olumide

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[threads] read_write_mutex and condtion
by Phil Endecott 01 Nov '05

01 Nov '05

Dear All, Is it possible to use a boost::condition in combination with a read_write_mutex? I've tried but failed. This is with 1.32.0. My test code follows. As you can see it can use either a mutex or a read_write_mutex depending on which bits are commented-out. It works as expected with a mutex, but with a read_write_mutex I get a compiler error, shown below. Perhaps I am missing some fundamental reason why conditions can't work with read_write_mutexes. Can someone explain? Thanks, Phil. #include <string> #include <iostream> #include <boost/thread/mutex.hpp> #include <boost/thread/read_write_mutex.hpp> #include <boost/thread/condition.hpp> #include <boost/thread/thread.hpp> #include <boost/bind.hpp> #include <unistd.h> using namespace std; using namespace boost; struct shared_thing { string data; //typedef mutex mx_t; //typedef mutex::scoped_lock read_lock; //typedef mutex::scoped_lock write_lock; typedef read_write_mutex mx_t; typedef read_write_mutex::scoped_read_lock read_lock; typedef read_write_mutex::scoped_write_lock write_lock; mx_t mx; condition cn; shared_thing::shared_thing(void): //mx() mx(read_write_scheduling_policy::writer_priority) {} void writer(void) { while(1) { sleep(1); { write_lock l(mx); data += "."; cn.notify_all(); } } } void reader(void) { while(1) { read_lock l(mx); cn.wait(l); cout << data << endl; } } }; int main(int argc, char* argv[]) { shared_thing t; thread wr_thread(bind(&shared_thing::writer,&t)); t.reader(); } $ g++ -pthread -O -Wall -o condvar condvar.cc -lboost_thread /usr/include/boost/thread/detail/read_write_lock.hpp: In member function `void boost::condition::wait(L&) [with L = boost::detail::thread::scoped_read_lock<boost::read_write_mutex>]': condvar.cc:51: instantiated from here /usr/include/boost/thread/detail/read_write_lock.hpp:297: error: ` boost::read_write_mutex&boost::detail::thread::scoped_read_lock<boost::read_write_mutex>::m_mutex ' is private /usr/include/boost/thread/condition.hpp:92: error: within this context

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problem with multi_index_container -> find
by Oliver.Kowalke＠infineon.com 01 Nov '05

01 Nov '05

Hello, I don't understand why this code doesn't compile (gcc-3.3.1) '... id_index.find( id) ...' ? Regards, Oliver #include <iostream> #include <string> #include <utility> #include <boost/multi_index_container.hpp> #include <boost/multi_index/key_extractors.hpp> #include <boost/multi_index/ordered_index.hpp> #include <boost/tuple/tuple.hpp> namespace mi = boost::multi_index; struct phonebook_entry { int id; std::string family_name; std::string given_name; phonebook_entry( int id_, std::string const& family_name_, std::string const& given_name_) : id( id_), family_name( family_name_), given_name( given_name_) {} }; typedef mi::multi_index_container< phonebook_entry, mi::indexed_by< mi::ordered_non_unique< mi::composite_key< phonebook_entry, mi::member< phonebook_entry, std::string, & phonebook_entry::family_name >, mi::member< phonebook_entry, std::string, & phonebook_entry::given_name > > >, mi::ordered_unique< mi::member< phonebook_entry, int, & phonebook_entry::id > > > > phonebook; void test_multi_index() { phonebook pb; phonebook::nth_index< 0 >::type & name_index = pb.get< 0 >(); std::string family_name("Mann"); std::string given_name("Thomas"); std::pair< phonebook::iterator, phonebook::iterator > p = name_index.equal_range( boost::make_tuple( family_name, given_name) ); while ( p.first != p.second) { std::cout << p.first->family_name << ", " << p.first->given_name << std::endl; ++p.first; } phonebook::nth_index< 1 >::type & id_index = pb.get< 1 >(); int id = 1; phonebook::iterator itr = id_index.find( id); // <<== doesn't // error: conversion from ` boost::multi_index::detail::index_iterator<boost::multi_index::detail::o rdered_index_node<boost::multi_index::detail::index_node_base<phonebook_ entry> > >' to non-scalar type ` // boost::multi_index::detail::index_iterator<boost::multi_index::detail::o rdered_index_node<boost::multi_index::detail::ordered_index_node<boost:: multi_index::detail::index_node_base<phonebook_entry> > > >' //requested phonebook::iterator end = id_index.end(); if ( itr != end) std::cout << itr->family_name << ", " << itr->given_name << std::endl; }

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