March 2006 - Boost-users - lists.boost.org

Trouble getting boost::ptr_container::ptr_map working
by Gustavo Ribeiro Alves 12 Mar '06

12 Mar '06

Hello, I'm writing an small library to represent types. Right now I'm focusing on representing type composition. For that I'm using the composite pattern as proposed by Gamma et al., so I have an abstract base class for my composites that has the virtual functions to addComposite members, but not their implementation. The header of my class looks like this: namespace dintype { class Type{ public: virtual ~Type()=0; typedef std::string Name_t; virtual void addComposition(const Name_t& name,Type* tp)=0; virtual void delComposition(const Name_t& name)=0; Type* clone() const; protected: typedef ptr_map<Name_t,Type> children_t; typedef children_t::iterator children_iterator; typedef children_t::const_iterator children_const_iterator; typedef children_t::size_type children_size_type; Type(); private: virtual Type* do_clone() const=0; }; inline Type* new_clone(const Type& c) { return c.clone(); } } The one for my composite class is: class CompositeType : public Type { private: children_t m_children; CompositeType(const CompositeType& r); virtual Type* do_clone(); protected: void clearAllCompositeChildren(); public: CompositeType(); virtual ~CompositeType(); virtual void addComposition(const Name_t& name,Type* tp); virtual void delComposition(const Name_t& name); }; Here is the implementation of the composite class: CompositeType::CompositeType(const CompositeType& r) : m_children(r.m_children.clone()) { } CompositeType::CompositeType() { } CompositeType::~CompositeType() { } void CompositeType::clearAllCompositeChildren() { m_children.erase(m_children.begin(),m_children.end()); } void CompositeType::addComposition(const Name_t& name,Type* tp) { m_children[name]=tp; // <========= THIS LINE IS THE PROBLEM } void CompositeType::delComposition(const Name_t& name) { m_children.erase(name); } I can't get the program to compile because gcc keeps complaining m_children[name] don't has operator= and that type is an abstract class and can't be initialized. I read all the boost::prt_container documentation and I couldn't find what I'm doing wrong. I also tried m_children.insert(name,tp); to no avail. I'll greatly appreciate any help. Thanks, Gustavo

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Boost.Thread-RWLock
by george 12 Mar '06

12 Mar '06

hello! until boost 1.33.0 there was in the lib(boost thread) the RW locks now in 1.33.1 is of for deadlock reasons as I know... what about the next version of boost(1.33.2(??)),it would have it again? in the sandbox there is something... does somebody know when the next version will be ready?? I am working on a project and I wanna use RW locks,I dont want to use 1.33.0 RW locks not becouse I am afraid deadlock,the use of them will be simple,but becouse I want to use the latest stable vesrion. thanks!

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Re: [Boost-users] multi_index 1.33.0, known problems with RHEL 3 compiler (gcc 3.2.3)?
by JOAQUIN LOPEZ MU?Z 12 Mar '06

12 Mar '06

----- Mensaje original ----- De: bert hubert <bert.hubert(a)netherlabs.nl> Fecha: Sábado, Marzo 11, 2006 6:39 pm Asunto: [Boost-users] multi_index 1.33.0,known problems with RHEL 3 compiler (gcc 3.2.3)? > Hi, > > Let me start off by saying that I consider multi_index to be the most > stunningly clever AND useful piece of c++ around. Thanks! > > A PowerDNS user on RHEL 3 with a gcc that calls itself 'gcc 3.2.3' > reportsthe following error compiling PowerDNS snapshot 576 > (http://svn.powerdns.com/snapshots/576/pdns- > 2.9.20.20060311.576.tar.gz):Message: > http://mailman.powerdns.com/pipermail/pdns-users/2006- > March/003134.html [...] > 285 typedef typename waiters_t::template index<KeyTag>::type > waiters_by_ttd_index_t;286 waiters_by_ttd_index_t& > ttdindex=d_waiters.get<KeyTag>(); > Any ideas, especially on a workaround? It compiles fine on all > gcc's I have > access to. > Hello Bert, I can try to investigate deeper into this next week, in the meantime let me suggest a couple of things: 1. Shouldn't be the expression waiters_by_ttd_index_t& ttdindex=d_waiters.get<KeyTag>(); written as waiters_by_ttd_index_t& ttdindex=d_waiters.template get<KeyTag>(); as d_waiters type is dependent on MTasker template args? Anyway, the error doesn't seem to be related to this, but who knows. 2. You might try the equivalent expression: waiters_by_ttd_index_t& ttdindex= boost::multi_index::get<KeyTag>(d_waiters); 3. Substituting identifiers (via an enum if you want to retain some legibility) for tags seem to reduce the stress on weaker compilers. If nothing of this works please let me know and I'll dig deeper once I've got access to a GCC environment next week. HTH, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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c++ parser with boost::spirit?
by Noel Yap 12 Mar '06

12 Mar '06

Has anyone created a c++ parser with boost::spirit? Thanks, Noel

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[PP] comma in macro expansions
by Marc Mutz 11 Mar '06

11 Mar '06

Hi, I'm having a problem with "free" commas in macro expansions. I want to generate some function declarations (and implementations) from a user-supplied BOOST_PP_SEQ. The function declarations use enable_if to switch between two sets of interfaces based on the type that shall be returned. Nevermind the details, I've just used a trivial enabling condition here, the error is the same as when using mpl::contains<sometype, Type> in the real code. I've stripped the problem down and attached a test file, complete with my documented attempts to delay expansion of the comma somehow. The preprocessor succeeds when the enable_if or it's two template args are put into (parentheses), but this is no longer valid C++, of course. I guess I'm missing something, but I'm at the end of my Latin, as we say in Germany. Thanks, Marc -- Marc Mutz -- marc(a)klaralvdalens-datakonsult.se, mutz(a)kde.org Klarälvdalens Datakonsult AB, Platform-independent software solutions

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boost::lambda question
by Robert Caldecott 11 Mar '06

11 Mar '06

OK, I'm a bit of a boost noob. I have a container of std::wstring's and I want to use a lambda expression in a for_each loop to pass each string to a WinAPI function - however, I need access to the c_str() method, and this is giving me a problem. For example, if I want to use the DeleteFile WinAPI call, I want to write something like: std::vector<std::wstring> v; ... for_each(v.begin(), v.end(), ::DeleteFile(_1)); But the above won't work as I need to pass the 'C' string to ::DeleteFile. So, I really want to be able to do something like this: for_each(v.begin(), v.end(), ::DeleteFile(_1.c_str())); Any ideas how I can access a member function (like c_str()) using a lambda placeholder?

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Re: [Boost-users] boost::lambda question
by Nat Goodspeed 11 Mar '06

11 Mar '06

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org [mailto:boost-users- > bounces(a)lists.boost.org] On Behalf Of Rob Caldecott > Sent: Saturday, March 11, 2006 12:36 PM > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] boost::lambda question > > Thanks Sebastian, but I am still struggling to make this work. I now get > the following error: > > "error C2664: 'DeleteFileW' : cannot convert parameter 1 from 'const > boost::lambda::lambda_functor<T>' to 'LPCWSTR'" [Nat] Don't you have to bind DeleteFileW as well? Something like (untested): for_each(v.begin(), v.end(), bind(::DeleteFileW, bind(&wstring::c_str, _1))); I think this phrasing should work with either boost::lambda::bind or boost::bind.

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multi_index 1.33.0, known problems with RHEL 3 compiler (gcc 3.2.3)?
by bert hubert 11 Mar '06

11 Mar '06

Hi, Let me start off by saying that I consider multi_index to be the most stunningly clever AND useful piece of c++ around. Thanks! A PowerDNS user on RHEL 3 with a gcc that calls itself 'gcc 3.2.3' reports the following error compiling PowerDNS snapshot 576 (http://svn.powerdns.com/snapshots/576/pdns-2.9.20.20060311.576.tar.gz) Message: http://mailman.powerdns.com/pipermail/pdns-users/2006-March/003134.html mtasker.cc: In member function `bool MTasker<EventKey, EventVal>::schedule() [with EventKey = PacketID, EventVal = std::string]': pdns_recursor.cc:723: instantiated from here mtasker.cc:286: no matching function for call to `boost::multi_index::multi_index_container<MTasker<PacketID, std::string>::Waiter, boost::multi_index::indexed_by<boost::multi_index::ordered_unique<boost::multi_index::member<MTasker<PacketID, std::string>::Waiter, PacketID, &MTasker<PacketID, std::string>::Waiter::key>, mpl_::na, mpl_::na>, boost::multi_index::ordered_non_unique<boost::multi_index::tag<MTasker<PacketID, std::string>::KeyTag, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, boost::multi_index::member<MTasker<PacketID, std::string>::Waiter, time_t, &MTasker<PacketID, std::string>::Waiter::ttd>, mpl_::na>, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, std::allocator<MTasker<PacketID, std::string>::Waiter> >::get()' make[3]: *** [pdns_recursor.o] Error 1 make[3]: Leaving directory /temp/pdns-2.9.20.20060311.576/pdns' To reproduce, download the tar file, run ./configure --with-modules="" ; cd pdns ; make pdns_recursor, besides boost there are no dependencies when compiled like this. Relevant details from mtasker.hh http://wiki.powerdns.com/projects/trac/browser/trunk/pdns/pdns/mtasker.cc?r… 60 struct KeyTag {}; 61 typedef multi_index_container< 62 Waiter, 63 indexed_by < 64 ordered_unique<member<Waiter,EventKey,&Waiter::key> >, 65 ordered_non_unique<tag<KeyTag>, member<Waiter,time_t,&Waiter::ttd> > 66 > 67 > waiters_t; 68 69 waiters_t d_waiters; >From mtasker.cc: http://wiki.powerdns.com/projects/trac/browser/trunk/pdns/pdns/mtasker.hh?r… 285 typedef typename waiters_t::template index<KeyTag>::type waiters_by_ttd_index_t; 286 waiters_by_ttd_index_t& ttdindex=d_waiters.get<KeyTag>(); Any ideas, especially on a workaround? It compiles fine on all gcc's I have access to. Thanks! -- http://www.PowerDNS.com Open source, database driven DNS Software http://netherlabs.nl Open and Closed source services

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Books on/using Boost
by Scott Meyers 11 Mar '06

11 Mar '06

I'm interested in books on or making significant use of Boost. Books on Boost include those on the BGL and the MPL, plus Karlsson's overview of Boost. Are there others? The only book I know of that makes extensive use of Boost is "C++ Cookbook" by D. Ryan Stephens et al. from O'Reilly. Are there others? Thanks, Scott

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[serialization] Creating new archives derived from polymorphic archive
by Robert S. Grimes 10 Mar '06

10 Mar '06

Hi, How do I get started? I want to create a set of custom archives that include such features as a small header, CRC, digital signatures, etc. I want to put this into a DLL, so I want to go the polymorphic route. There are directions for creating new archives from the template versions, but not for the polymorphic versions. I'm not sure the starting point is the same, so I thought I'd ask first, as this is stretching my abilities a bit. Thanks, -Bob

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