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Re: [Boost-users] [boost] [Filesystem V3] Filesystem Version 3 beta 1 available for download and comment
by Beman Dawes 20 Feb '10

20 Feb '10

On Thu, Feb 18, 2010 at 11:30 AM, Zach Laine <whatwasthataddress(a)gmail.com> wrote: > On Thu, Feb 18, 2010 at 8:43 AM, Beman Dawes <bdawes(a)acm.org> wrote: >> The first beta release of Boost.Filesystem Version 3 is now available. >> >> The documentation can be viewed at http://mysite.verizon.net/beman/v3/index.htm > > The descriptions for portable_name() and portable_directory_name() > appear to be at odds. > > portable_name() : ... && (name is "." or "..", and the first character > not a period or hyphen) > > portable_directory_name(): ... && (name is "." or ".." or contains no periods) > > Should portable_name() be "... && (name is "." or "..", or contains no > periods) && (first character not a hyphen)"? Maybe I'm missing > something? I haven't looked at these in years. They need to be brought up to date. Added to do list. > > Also, in the tut3.cpp tutorial code, there's no mention of the dangers > of using "*it" inside the directory_iterator loop. IIRC, in previous > Filesystem revisions, this would throw if you did not have adequate > permissions to see the file to which "it" refers. Has this changed? Nice catch! No, nothing is changed. The code is not robust. > If not, I think that you should either wrap the body of the loop in a > try-catch block, or use one of the non-throwing function overloads, > and indicate to the user what the exception safety concerns are. Yes, this would be a great place to introduce the non-throwing function overloads. Added to do list. I > think the tutorial code should exhibit enough robustness that the user > can just cut-and-paste to get the basic code needed to use the > library. Definitely. If anyone spots other robustness issues, be sure to let me know. Thanks, --Beman

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mpl Generate integral sequence wrapper from 0 to N
by Hicham Mouline 20 Feb '10

20 Feb '10

Hi, Given a size_t N known at compile, what's the cleanest way to generate mpl::vector_c<size_t, 0, 1, .., N> what is the fastest way compile-time wise? what is the most mpl algos reusing way? Regards,

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Inconsistent unicode encoding between boost and wx on mac osx
by Sachin Garg 19 Feb '10

19 Feb '10

My project uses both boost and wxwidgets and unicode encoding by both is different on Mac OSX. Everything works fine on windows. Problem: Boost and WX do end up encoding the strings differently when converting to unicode on OSX. I am detailing an example: WX's encoding is same on both windows and osx but Boost's encoding is different on both platforms. It is probably not a bug but I am unable to figure out the reason and how to make them both work together. The string: 国際的な一流のホールダー (I don't know if this foreign language string will show up fine in your email client). Hex dumps of Unicode encodings of this string >From Boost on Mac (32-bit): e5 0 0 0 9b 0 0 0 bd 0 0 0 e9 0 0 0 9a 0 0 0 9b 0 0 0 e7 0 0 0... >From WX on Mac (32-bit): fd 56 0 0 9b 96 0 0 84 76 0 0 6a 30 0 0 0 4e 0 0.... >From WX and Boost on Windows (16-bit): fd 56 9b 96 84 76 6a 30 0 4e 41 6d 6e 30... (To be more exact, this is how boost::filesystem encodes a directory name it read from disk, and its the wxChar** argv value from wxApp for a Unicode build of wx). So wx does same thing on windows and mac, and boost does that same thing on windows. But boost encodes it differently on mac and I have no idea why. My wild guess is its due to locale etc settings but I don't know how check for this or fix it. SG

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[graph] boost::adj_list_edge_property_map
by Christine SINOQUET 19 Feb '10

19 Feb '10

Hello, I encounter some problems when porting an application using boost from Windows to Linux. I work with Ubuntu, I use codeblocks as a compiling environment. The boost library I use is boost_1_38 containing boost_1_38/boost/property_map.hpp boost_1_38/boost/config.hpp boost_1_38/boost/graph/adjacency_list.hpp boost_1_38/boost/graph/graph_utility.hpp. I believe the boost library is compatible with Windows and Linux. The compiler reports the following errror: .../structure_learning/src/graph_tools/GraphPDAG.cpp:295 erreur: conversion from "boost::adj_list_edge_property_map<boost::bidirectional::tag, boost::detail::error_property_not_found, boost::detail::error_property_not_found&, void*, boost::property<boost::edge_weight_t, long double, boost::no_property>, boost::edge_bundle_t" to non-scalar type "boost::no_edge_bundle" requested. Then, it finds a second error: .../structure_learning/src/graph_tools/GraphPDAG.cpp:296 erreur: "struct boost::no_edge_bundle" has no member named "ambiguous". Finally, the third error is (after verbose comments which I can not copy here): GraphPDAG.cpp:296: instantiated from here: boost_1_38/boost/graph/adjacency_list.hpp:463:erreur:invalid initialisation of reference of type "boost::no_edge_bundle&" from expression of type "boost::detail::error_property_not_found". Do you have any idea why this code is correct with Windows but not with Linux ? I would have thought that the boost C++ library is compatible with any system. Thank you in advance for considering my questions. Best regards, C.S. //============================================================================== void PDAG::putWeightPDAG(slBayesianNetwork* bn, slEdge e, int w) { unsigned int a, b; this->pBN = bn; this->getEdgeNodesIndex(e, a, b); this->putWeightPDAG(a, b, w); slGraph& graph = bn->get_graph(); property_map<slGraph, edge_weight_t>::type weightMap = get(edge_weight, graph); line 295 >>>>> edge_bundle_type<slGraph>::type ambiguousTypeMap = get(edge_bundle, graph); line 296 >>>>> graph[e].ambiguous = true; }

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MPL. Difference between variadic and numbered forms of sequences
by dilas dilas 19 Feb '10

19 Feb '10

When I write expressions like: template<class Seq, class Elem> struct pairs: fold<Seq, vector<>, push_back<_1,vector2<Elem, _2 > > >{}; Everything works just fine, but when I use variadic form: template<class Seq, class Elem> struct pairs: fold<Seq, vector<>, push_back<_1,vector<Elem, _2 > > >{}; I have a lot of errors. Can someone explain me what's the difference?

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Cost of constructing models of RandomDistribution
by Robert Patterson 19 Feb '10

19 Feb '10

I have a fairly large simulation code, that I need to get into a state in which I can multi-thread it. One of my problems is a global random number generator state. I am thinking that I should replace this global object with a collection of generator engines, one for each thread, which would be passed down by non-const reference from the top level of each thread to the places where random numbers are needed. In this case it seems best to pass around engines that model PseudoRandomNumberGenerator. In each place that I want a random number (I rarely need more than 1 or 2 at once or with the same parameters) I would then have to construct and use a RandomDistribution, such as uniform_int, exponential_distribution (or poisson, but that is a question for another day). This approach relies on these models of RandomDistribution being fairly cheap to construct. I cannot see any reason why this should not be the case, but equally I cannot see any promise in the docs that they will be cheap to construct. Am I proposing to use the library in a sensible way? Thanks Robert Patterson

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doubt on boost::bind and boost::function
by Conoscenza Silente 19 Feb '10

19 Feb '10

Hi all I am trying to use boost::function combined with boost::bind in order to be able to pass a callback to another function. The callback I want to pass is a member function of the class. The code is below class CA{ bool IsMemberFunction( const std::string& aLine ){ return true; } void testUseFooPtr( boost::function< bool(const std::string& ) > aFooPtr ){ std::string aLine; // read from somewhere if( aFooPtr( aLine ) ){ std::cout << "is fine" << std::endl; } } void testFooPtr(){ std::string ciao("aa"); boost::function< bool(const std::string& ) > fooPtr( boost::bind( &CA::IsMemberFunction, this ) ); // create // a boost function using the class memebr testUseFooPtr( fooPtr ); // pass it as callback to another // function } }; I have the following compilation error. /usr/local/include/boost/bind/mem_fn.hpp:342: error: invalid use of non-static member function Do you know what I am doing wrong? Is the signature fine? Thanks

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error: no matching function for call to ‘boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> >::basic_stream_socket()’
by David Kaplan 19 Feb '10

19 Feb '10

Hi Why doesn't this work: _socket = tcp::socket(ioService); _socket is a private member of type tcp::socket. How can I store the socket as a class member (so I can access it when using read/write from other class methods)? Also, is there any way to define a timeout on a synchronous connect()? If not, what's the workaround? Can I do an async connect and then somehow return to synchronous mode of operation? Thanks, David

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[Random] random_device not available for linking?
by Roland Bock 19 Feb '10

19 Feb '10

Hi, I tried to experiment with boost::random_device (e.g. http://www.boost.org/doc/libs/1_42_0/libs/random/nondet_random_speed.cpp) but failed to link it: randomTest.cpp:36: undefined reference to `boost::random_device::operator()()' randomTest.o: In function `main': randomTest.cpp:57: undefined reference to `boost::random_device::default_token' randomTest.cpp:57: undefined reference to `boost::random_device::random_device(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)' randomTest.cpp:63: undefined reference to `boost::random_device::~random_device()' There seems to be a boost_random library missing. I am using Ubuntu-8.04, 64bit with gcc-4.2.4. Thanks and regards, Roland

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转发: How to detatch native socket from boost asio basic_socket?
by BlueStone 19 Feb '10

19 Feb '10

Hey! In my scenario, first, I use ip::tcp::acceptor to accept an incoming connection request, and got the basic_socket instance, then I read some data from it, and after checking validity of the data received, I need to create another class to manage i/o operation with this basic_socket instance. And at this point, in my opinion, I must detach native socket from the previous instance of basic_socket, and assign it to the new one, but I cannot find that asio provide the method to detach native socket from the basic_socket. How can I do ? Any advice will be appreciated.

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Boost Threading Multiple Reader / Single Writer Usage Questions
by Brian Nantz 19 Feb '10

19 Feb '10

I am working in legacy code and I have a list collection of pointers that is accessed by multiple threads. I am having some thread locking issues with it. Mostly the list is read and very few changes (adds or deletes) are made to the list. I thought this would be a great opportunity to use a Reader Writer Lock (RWL). It seems that the shared_mutex is the Boost RWL. There are a few requirements that I am not sure shared_mutex will do for me: 1. There could be nested locks and the RWL should handle unwinding them correctly. I see that recursive_mutex seems to handle that. Does shared_mutex handle that as well? 2. Is there a way to give a higher priority to writes? I am worried about the readers starving the writers, so I would like any pending writers to be given preference over pending readers. How can I get this functionality from the Boost thread library? If I need to build my own, what class do you recommend using as a base to build from?

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Re: [Boost-users] Object pools?
by michele.caini＠gmail.com 19 Feb '10

19 Feb '10

Hi, of course, in my opinion pool has to manage objects life time. However sharing objects with pool owner by shared ptr seems to be a good idea, because pool still manages objects life time. Using shared pointer also inside pool solves the problem, maybe. It is correct? ----- Reply message ----- Da: "Ryan McConnehey" <mccorywork(a)gmail.com> Data: gio, feb 18, 2010 02:50 Oggetto: [Boost-users] Object pools? A: <boost-users(a)lists.boost.org> Michele Caini wrote: > Pool will create objects, pool will release and reclaim objects, and pool will delete > objects. > If the pool manages the life time of the object then the pool can't release the object, correct. The pool will at most loan the object to the user. > You are looking for something that create objects and forbid about them, > until you return that objects to the home. Is correct? > Did you mean forget instead of forbid. The kind of pool I'm talking about would only forget about those objects that it released. It still needs to manage the life time of the objects it didn't release. > Really, it's possible but it is not as a pool works, simply. > Are you stating that Boost.Pool doesn't work this way or all pools? Is there a definition for a pool that I'm missing. I thought a pool was a collection of objects and an object could be provided to the user. The implementation and life time of the object were left up to the pool. > Your idea breaks also raii pattern and you risk to have memory leaks, > because not reclaimed objects maybe be lost during their life time. > In my requirements, to avoid memory leaks, the objects were passed to the user with a boost::shared_ptr. > What about a monostate pattern that globally manages objects as a pool > and will be destroyed only when program terminates? That's can be a > valid alternative, or not? > I believe the monostate pattern shares its (static) data. Wouldn't this mean the amount of data can't be increased? If the data can't be increased it not as useful to the user when all the objects have been used but more are still needed. Ryan _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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[1.41.0] Intel 11.1 Linux vs. cmath header
by Richard Hadsell 19 Feb '10

19 Feb '10

I am trying to build the Boost 1.41.0 libraries with an evaluation copy of Intel C++ 11.1 for 64-bit Linux. My system is Fedora 12 with G++ 4.4.3 installed as the default compiler. This fatal error is preventing most of the libraries from building: /usr/include/c++/4.4.3/cmath(500): error: identifier "__builtin_fpclassify" is undefined return __builtin_fpclassify(FP_NAN, FP_INFINITE, FP_NORMAL, ^ detected during: instantiation of "__gnu_cxx::__enable_if<std::__is_arithmetic<_Tp>::__value, int>::__type std::fpclassify(_Tp) [with _Tp=float]" at line 65 of "./boost/functional/hash/detail/hash_float.hpp" instantiation of "size_t={unsigned long} boost::hash_detail::float_hash_value(T) [with T=float]" at line 282 of "./boost/functional/hash/hash.hpp" I am building the libraries with this command: bjam toolset=intel-linux threading=multi variant=release link=static,shared --stagedir=stageIF12 stage Release notes seem to indicate that someone has successfully built Boost libraries with Intel 11.1 and G++ 4.4.1 (whose cmath header looks the same as for 4.4.3). I have not used the Intel compiler for several years, so I may be missing something that is familiar to other users. Help? -- Dick Hadsell 203-992-6320 Fax: 203-992-6001 Reply-to: hadsell(a)blueskystudios.com Blue Sky Studios http://www.blueskystudios.com 1 American Lane, Greenwich, CT 06831-2560

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[spirit] first steps
by Igor R 18 Feb '10

18 Feb '10

Hello, How to use the string parser? I tried this way: std::string s1; bool r = qi::phrase_parse(first, last, ( string[ref(s1) = _1] ) , space); But it doesn't compile. Thanks.

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mpl for_each: stop applying functor when runtime predicate is true
by Hicham Mouline 18 Feb '10

18 Feb '10

With a mpl sequence, applying a functor f with for_each on that sequence applies f at runtime on every element of the sequence. If I wish to stop applying f once I've found the element in the sequence which satisfies some runtime predicate, how can I do that? I'm thinking of putting a bool state in f, and turn it to false once I decide not to apply anymore, and on invocations of, just do nothing when the state is false. Any better way of doing this? Regards,

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[Iostreams] unresolved problem
by Michał Nowotka 18 Feb '10

18 Feb '10

Hello, I have the same problem as described here: http://thread.gmane.org/gmane.comp.lib.boost.user/34531 . There wasn't any answer to this post and it was asked over a year ago. I think this is quite important. Can anyone can help? -- Regards Michał Nowotka

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tokenize string delimiter
by Lloyd 18 Feb '10

18 Feb '10

Hi, Is it possibleto tokenize a string based on a string delimiter? Thanks, Lloyd ______________________________________ Scanned and protected by Email scanner

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fusion: work of 4 sequences at the same time
by Hicham Mouline 18 Feb '10

18 Feb '10

Hi, I am trying to apply fusion::for_each on a sequence, but inside the unary functor applied to each element, I need to know the index of the element in question, because I need to extract elements with the same index from other sequences. fusion::vector<...> fseq1; fusion::vector<...> fseq2; fusion::vector<...> fseq3; fusion::vector<...> fseq4; fusion::for_each( fseq1, functor<...>(fseq2, fseq3, fseq4) ); template <typename Seq2, typename Seq3, typename Seq4) struct functor { /// ctor template <typename T> void operator()( const T& t) const { /// find out index of t in fseq1, /// use elements from fseq2,3,4 at the same index } }; I could use boost::fusion::find to get an iterator and then get its index, but this doesn not look clean, Any ideas, Rds,

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Re: [Boost-users] fusion: work of 4 sequences at the same time
by Hicham Mouline 18 Feb '10

18 Feb '10

> -----Original Message----- > From: Hicham Mouline [mailto:hicham@mouline.org] > Sent: 18 February 2010 17:38 > To: 'boost-users(a)lists.boost.org' > Subject: fusion: work of 4 sequences at the same time > > Hi, > > I am trying to apply fusion::for_each on a sequence, but inside the unary > functor applied to each element, I need to know the index of the element in > question, because I need to extract elements with the same index from other > sequences. > > fusion::vector<...> fseq1; > fusion::vector<...> fseq2; > fusion::vector<...> fseq3; > fusion::vector<...> fseq4; > > fusion::for_each( fseq1, functor<...>(fseq2, fseq3, fseq4) ); > > template <typename Seq2, typename Seq3, typename Seq4) > struct functor { > /// ctor > > template <typename T> > void operator()( const T& t) const > { > /// find out index of t in fseq1, > /// use elements from fseq2,3,4 at the same index > } > }; > > I could use boost::fusion::find to get an iterator and then get its index, but > this doesn not look clean, > > Any ideas, > > Rds, > Ah! fusion::zip is my friend. fusion::for_each( fusion::zip(fseq1, fseq2, fseq3, fseq4), functor() ); Could u confirm though that I will be able to modify fseq1, even through the zipping? Rds,

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Transfering the process state to another process
by Lloyd 18 Feb '10

18 Feb '10

Hi, We want to have a program which cannot be terminated by the user (even admin). I think the only way to do this is to write a watchdog process. So there will be a master and a slave process, the master will be the active process, and the slave keep on watching the master. I case if the master is terminated, the slave become master and initiates a new slave process. But we need to transfer (or share) the process state of "old master" with the "new master" (So that the new master can continue form where the old master has stopped). Is this possible with shared memory? Or is there is a better way? Thanks, Lloyd ______________________________________ Scanned and protected by Email scanner

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multichar_input_filter, what I'm doing wrong?
by eial＠cs.bgu.ac.il 18 Feb '10

18 Feb '10

I'm implementing a base64 decoder using multichar_input_filter, it works well but it doesn't seems to stop, after the last char of the testcase string (which is reads from file), it continues to read, I must be missing something, here is the code: http://codepad.org/YvKREpKS the convert funcion does the actual convert and I don't think it is relevant to the code but if someone thinks it is, I'll include it. I'm banging my head against the wall for a couple of days in this issue... thanks.

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fusion: mpl vector as a fusion vector
by Hicham Mouline 18 Feb '10

18 Feb '10

Hello by include <fusion/include/mpl.hpp> if I have a mpl::vector<> and I want to use it as a member of a struct. This member will actually hold runtime data. typedef mpl::vector<......> mplvector_t; can I just define it as struct S { mplvector_t m; }; or do I need to do this: struct S { fusion::result_of::as_vector<mplvector_t>::type m; }; and then I can store data in m? Regards,

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boost::asio - Can't get timeout on accept to work
by Jean-Sebastien Stoezel 18 Feb '10

18 Feb '10

Hello, I would like to implement a timeout while accepting a connection on a TCP socket. I have reviewed the following example: http://www.boost.org/doc/libs/1_42_0/doc/html/boost_asio/example/timeouts/a… And here is my implementation of it, though it does not seem to wait for the given timeout... And I don't seem to see CProtobufSocket::HandleAccept being called. Could anybody tell me what I am missing with this code? Thanks! Jean-Sebastien int CProtobufSocket::Receive( string port, google::protobuf::Message & message, const boost::posix_time::milliseconds timeout ) { int result = -1; boost::asio::io_service ioService; boost::asio::ip::tcp::acceptor acceptor(ioService, boost::asio::ip::tcp::endpoint(boost::asio::ip::tcp::v4(), atoi(port.data()))); boost::asio::ip::tcp::socket socket(ioService); try { boost::asio::deadline_timer mytimer(ioService); acceptor.async_accept(socket, boost::bind(CProtobufSocket::HandleAccept, boost::asio::placeholders::error, result)); mytimer.expires_from_now(timeout); mytimer.async_wait(boost::bind(CProtobufSocket::Close, &acceptor)); if(0 == result) { // receive on the socket. result = Receive(socket, message, timeout); } else {} } catch (std::exception& e) { // jstoezel 2910208: removes warning C4101: 'e' : unreferenced local variable e; } try { socket.shutdown(socket.shutdown_both); socket.close(); } catch (std::exception& e) { // jstoezel 2910208: removes warning C4101: 'e' : unreferenced local variable e; } return result; } void CProtobufSocket::Close( boost::asio::ip::tcp::acceptor * acceptor ) { acceptor->close(); } void CProtobufSocket::HandleAccept(const boost::system::error_code &err, int & result) { err; if(err) {} else { result = 0; } }

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Re: [Boost-users] Object pools?
by Michele Caini 18 Feb '10

18 Feb '10

Il 17/02/2010 17:18, Ryan McConnehey ha scritto: > michele.caini(a)gmail.com wrote: >> Simply, That's not as a pool have to work. You are looking for >> something that is a pool but working not as a pool does. > Then what is the definition of a pool? Do you mean that I'm looking for > something that is a pool but doesn't work like a Boost.pool? > > Ryan No, sorry. I mean that pool has responsability for manage offered objects, and so it manages them along their life time. Pool will create objects, pool will release and reclaim objects, and pool will delete objects. That's all. You are looking for something that create objects and forbid about them, until you return that objects to the home. Is correct? Really, it's possible but it is not as a pool works, simply. Your idea breaks also raii pattern and you risk to have memory leaks, because not reclaimed objects maybe be lost during their life time. So, in my opinion, it is not a good idea. I think that is better to create a pool of object during pool construction, so delete them during destruction, eventually resizing pool during use. What about a monostate pattern that globally manages objects as a pool and will be destroyed only when program terminates? That's can be a valid alternative, or not?

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[parameter][mpl] How to do a union of ArgumentPacks?
by Jesse Perla 17 Feb '10

17 Feb '10

I would like to call a function using named parameters where I construct the values from two different argument packs. How do I write a function that will generically take the union of all of the named parameters? I am using Intel C++ 11.1 with C++0X features turned on, so 'decltype' and 'auto' are kosher, but not alternative function syntax. Also, the types I might have in the args could be by value or reference or constant reference, so I can't just copy them all by value. Here is a simple example to see what I mean: BOOST_PARAMETER_NAME(name1) BOOST_PARAMETER_NAME(name2) BOOST_PARAMETER_NAME(name3) template<typename ArgPack> double f(const ArgPack& args) { return args[_name1] + args[_name2] + args[_name3]; } //Test using the argpack directly... this works fine. std::cout << f( (_name1 = 1.0, _name2 = 1.0, _name3 = 1.0) ); //Now try to combine them: template<typename ArgPack1, typename ArgPack2> double g(const ArgPack1& args1, const ArgPack2& args2) { return f( parameter_union(args1, args2) ); //HOW DO I WRITE THE parameter_union FUNCTION? } //usage std::cout << g( (_name1 = 1.0, _name2 = 1.0), (_name3 = 1.0) ); Thanks for your help, Jesse

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