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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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Re: [Boost-users] [Multi-Index] composite_key problems
by JOAQUIN LOPEZ MU?Z 31 Oct '05

31 Oct '05

----- Mensaje original ----- De: Andreas Volz <lists(a)brachttal.net> Fecha: Lunes, Octubre 31, 2005 7:27 pm Asunto: Re: [Boost-users] [Multi-Index] composite_key problems > The questions seems to by stupic, but how > could I > access the data looked up by B alone? What should I assign to the > left? > > ??? = es.get<1>().find(b); > > An iterator or what else? This returns an iterator, yep. Please notice that es.get<1>() returns a reference to an index, which is, in many respects, entirely similar to a regular std::set. So you have find(), equal_range() etc. just like in the STL case, with equivalent syntax and semantics. You might want to give the Boost.MultiIndex tutorial a further read --anyway, don't hesitate to come back here if things aren't still clearer. Joaquin M Lopez Muñoz Telefonica, Investigacion y Desarrollo

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Re: [Boost-users] Translating an absolute path to a path relative
by Gottlob Frege 31 Oct '05

31 Oct '05

> > Date: Mon, 31 Oct 2005 09:55:57 -0300 > From: Hermann Rodrigues <hermann.rodrigues(a)gmail.com> > Subject: [Boost-users] Translating an absolute path to a path relative > to the current directory > To: boost-users(a)lists.boost.org > Message-ID: > <497dfc460510310455j1bd56615peffd2f6040fe849e(a)mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > Hi, > > I am running into the following problem these days: > > I need to translate an absolute path to a path relative to the current > directory on Windows. The translation process need to include all > required ".." directory specifiers in the path to make sure it can be > accessed from the current directory. > > Have you tried the Windows functions such as PathRelativePathTo, and its compliment PathCombine?

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[BUG] missing references in docs on web site (threads)
by Ross Boylan 31 Oct '05

31 Oct '05

While reading the web pages for the threads library I noticed some missing references. I don't know if they reflect a problem with the documentation source or a problem with the processing converting the source into html (if there was any such processing). I did check the html source of teh web pages to verify that it wasn't a display problem with my browser. http://boost.org/doc/html/threads.html#id1357380 In "Potentially non-thread-safe functions" this appears: "It is possible to write thread-safe implementations of these by using thread specific storage (see boost::thread_specific_ptr), and several C++ compiler vendors do just that. The technique is well-know and is explained in ." The reference at the end is missing. I thought I saw another example like this in the threads doc, but can't find it now. Also, the quote from Brinch Hansen at the end of http://boost.org/doc/html/threads/rationale.html doesn't indicate the source (though one could at least guess the article from the bibliography, though he's co-author of another one in the bibliography).

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Re: [Boost-users] [Multi-Index] composite_key problems
by Andreas Volz 31 Oct '05

31 Oct '05

Am Mon, 31 Oct 2005 18:14:00 +0100 schrieb JOAQUIN LOPEZ MU?Z: > // lookup by (A,B); > > es.find(make_tuple(a,b)); > > // lookup by A alone > > es.find(make_tuple(a)); > > // lookup by B alone > // note get<1> retrieves the second index. > > es.get<1>().find(b); > > Is the issue clearer now? If not, please tell me > so and I'll try to explain myself a bit further. A little clearer, but not at all. I'm really new to Boost, so I doesn't understand all. The questions seems to by stupic, but how could I access the data looked up by B alone? What should I assign to the left? > ??? = es.get<1>().find(b); An iterator or what else? There was a print_out_by_name function in docs that I tried to adopt, but I failed. And the compile errors are not very helpfull. As normal with template programming :-( regards Andreas

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[Boost.filesystem] Support of Unicode OS ?
by Marc Viala 31 Oct '05

31 Oct '05

Hi, I would like to know if there are some implementations of "Boost.filesystem" to support Unicode OS like Windows XP? We are involved in a large project, we use Boost libraries intensively, version 1.33, and we are looking forward for this mandatory feature. Thanks in advance for your reply. Marc Viala www.acticm.com <http://www.acticm.com> mailto:mviala@acticm.com <mailto:mviala@acticm.com>

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C++ Connections question
by Elisha Berns 31 Oct '05

31 Oct '05

Ok, So this isn't a Boost.X question, but I have to ask since Dave Abrahams is giving two talks at the C++ Connections conference next week. The question is since the sessions, any session not just Dave's, are either only 60 or 75 minutes max, how informative and in depth can they possibly be? It would appear they are only to whet one's appetite for learning something, but that is precisely my question. Thanks for offering an appraisal whether this conference is really worth the bother. Elisha Berns e.berns(a)computer.org tel. (310) 556 - 8332 fax (310) 556 - 2839

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