January 2008 - Boost-users - lists.preview.boost.org

BGL: Problem accessing property_map members
by James Jackson 25 Jan '08

25 Jan '08

Hi, I am trying to use the BGL to model a simple directed graph with internal edge properties. Following the example given in the documentation[1], I have done the following (with question-irrelevant padding removed): ------------------------------- #include <boost/graph/adjacency_list.hpp> #include <boost/property_map.hpp> typedef boost::property<boost::edge_weight_t, double> EdgeProperties; typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, boost::no_property, EdgeProperties> NetworkGraph; typedef std::pair<int, int> Edge; NetworkGraph g(5); boost::add_edge(0, 1, g); boost::add_edge(0, 2, g); boost::add_edge(1, 3, g); boost::add_edge(2, 3, g); boost::add_edge(3, 4, g); boost::property_map<NetworkGraph, boost::edge_weight_t>::type weights = boost::get(boost::edge_weight_t(), g); weights[0] = 1.0; weights[1] = 1.0; weights[2] = 1.0; weights[3] = 1.0; weights[4] = 1.0; ------------------------------- Which all looks fairly kosher. However, attempting to compile this results in a error on each of the weights assignment lines: "error: no match for 'operator[]' in 'weights[0]' Using the syntax boost::put(weights, 0, 1.0) just moves this error inside a parameter_set template definition. Can anybody shed any light on this? For the record this is on MacOS X 10.5.1, with GCC 4.0.1 (i686-apple-darwin9-gcc-4.0.1). Regards, James Jackson. [1] interior_property_map.cpp

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BoostCon 2008 Now Open For Registration
by David Abrahams 25 Jan '08

25 Jan '08

Hi All, The 2nd annual Boost Conference has been scheduled for May 4-9 2008. Please see http://www.boostcon.com/registration for registration information. If you want to stay at the Aspen Meadows (highly recommended as it is within walking distance of the conference venue and was the site of great after-hours discussions in '07), it's especially important this year that you book your rooms early. Since, unlike last year, Aspen's airport will be open this May, demand for rooms has been heavy. In fact, the following week, which we tried to get, was snapped up by another group before we even had a chance to catch our breath, just weeks after BoostCon'07 ended. We'll be working hard on getting the program together for 2008 over the coming weeks. We hope to include many more Boost authors and contributors, and build in several more intensive library-specific sessions, to make 2008 better than ever. Please send any questions to the BoostCon planning committee at: organizers(a)boostcon.com. Those of you who didn't make it to BoostCon'07 may want to have a look at the photo gallery at http://boostcon.com/community/photos, peruse the 2007 program at http://boostcon.com/program, and check out the two trip reports mentioned here: http://boostcon.com/news/2007/Jul/16/yet-another-trip-report. See you in Aspen! -- The BoostCon Planning Committee

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Problems using Boost.Threads
by anthony kelly 25 Jan '08

25 Jan '08

Hello Boost Users, I am trying to use Boost.Thread in my application. I am compiling on Windows for Windows using Cygwin GCC with the "no-cygwin" option. Boost.Build is far too complicated for my application, so I am using a simple Makefile. I don't mind whether I use Windows threads or POSIX threads, but I have tried both and I can't get either to work. Re: Windows threads, I have static linked to "boost_thread-gcc34-mt-1_34_1" (no plan to use unsupported tss), and I defined BOOST_THREAD_USE_LIB and BOOST_HAS_WINTHREADS, however I get a lot of error messages about pthread functions not found. Have you any idea why I get error messages about using pthread functions when BOOST_HAS_WINTHREADS is defined? Is there some other macro(s) which should be defined? Re: POSIX threads, I have static linked to "boost_thread-gcc34-mt-1_34_1" and "pthreadGC2" (pthreads-win32), and I defined BOOST_THREAD_USE_LIB and BOOST_HAS_PTHREADS, however I get an error message that nanosleep is not found. I read that nanosleep is part of libc, so I added "c" to my list of static libraries, which finds nanosleep, but then I receieve other errors which looks as though I am linked to multiple C runtimes. What is the correct approach to link nanosleep in this configuration? If you have any suggestion, please let me know! Thanks in advance for your time. Kind regards, Anthony P.S. Is there a resource which can tell me which are the prerequisite libraries for boost libraries (e.g. pthreads or winsock)? So far, I have had to guess appropriate libraries based on internet searches for the function names appearing in "undefined reference" errors, but this seems very clumsy!

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[ublast] sparse matrix - resize with preserve
by Olivier Jouny 24 Jan '08

24 Jan '08

I would like to use the resize method of mapped_matrix with preserve = true but it does not work. By looking at the implementation, a comment says not implemented :-( Can you confirm ? If it's the case, does somebody has a work around ? Regards, Olivier. _________________________________________________________________ Comme 9 millions de français, créez un compte Hotmail ! http://www.windowslive.fr/hotmail/default.asp

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Storing types in a non-template class?
by Robert Dailey 24 Jan '08

24 Jan '08

Hi, I have a singleton class called InputRegistry. Before the class is used, the user must call: InputRegistry::Initialize(); I would like this function to take a parameter that defines the type of a critical section object, which is unknown at compile time (template). I need to store this type in my InputRegistry class so that the unknown critical section type can be constructed later. How can I do this without making InputRegistry a template class? If I make InputRegistry a template, that basically means I need to redesign the class, as the singleton pattern would not apply if it were a template class. I'm hoping boost can help here. Thanks in advance.

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[Singleton] pre-review question
by Ovanes Markarian 24 Jan '08

24 Jan '08

Hello, I am currently evaluating boost.singleton for our application. I hope it is not too late to write a review. As I understood from the docs, Singleton instance is immediately (when all global and static variables are initilized) created. In our context we need singleton to be created on first request (as it is described in GoF). The problem is following: Our application must parse config file which is accessible after entering main and store the options/parameters parsed in a singleton class. If I initialize singleton immediately (before entering main) I can not parse command line options and have to trick around with some additional functions which do it for me (but a constructor would be a much better choice, when I try for the first time to access the singleton). Is that possible with the current implementation? I know I could overload operator-> and check that options are parsed, but I think this is a not so obvious scenario for everyone. With Kind Regards, Ovanes

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cygwin buit boost libraries do not work
by Steven Woody 24 Jan '08

24 Jan '08

Hi folks, I have buit boost in cygwin followed instruction in the boost getting start documentation. it seemed successful and many libraries ( including dynamic and static ones ) were put into /usr/local/lib. I then try to compile a very simple example code listed as blow, which are a copy on the boost documentaion. #include <boost/regex.hpp> #include <iostream> #include <string> int main() { std::string line; boost::regex pat( "^Subject: (Re: |Aw: )*(.*)" ); while (std::cin) { std::getline(std::cin, line); boost::smatch matches; if (boost::regex_match(line, matches, pat)) std::cout << matches[2] << std::endl; } } What I did is, g++ -I/usr/local/include RegexSample.cpp -o RegexSample -L/usr/local/lib -lboost_regex but the resulting RegexSample.exe can not run properly -- it simply exist with an error code ( 53 ) and do nothing for me. My question is: is there anything different for Boost on Cygwin? The procedure I used to buid Boost on Cygwin is provided as below. Please check it can tell me if there is anything wrong. Thanks! --------- 1, build the bjam using './build.sh gcc' under the tools/jam/src directory and then copy bjam.exe to a place searchable; 2. 'bjam --builddir=~/tmp --toolset=gcc --layout=system --without-python install' ----------- -- woody then sun rose thinly from the sea and the old man could see the other boats, low on the water and well in toward the shore, spread out across the current.

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Re: [Boost-users] Multiple templates singletons
by Hicham Mouline 24 Jan '08

24 Jan '08

I omited to show the definition of those templates TreeImplBase.They would have the map as a private member,as protected members, functions to insert instances in the map, called by the ctors of derived templates. I will look at boost::fusion thanks, ----- Original Message ----- From: "Ovanes Markarian" To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] Multiple templates singletons Date: Thu, 24 Jan 2008 00:02:01 +0100 Hello! I have a question to this construct: template <typename contractType, typename treeType> class TreeImplBase; Each specialization of these holds a static std::map< boost::tuple<int,enum1,enum2,enum3>, const TreeImplBase* >; which contains the list of the derived template classes. How can you instantiate a pointer to the class temlate? Class template is an incomplete type. You will not be able to specify a pointer to it. I think you should use boost::fusion inplace. This lib, offers a compile time map (if you map the same time to an instance of it, use a fusion set), which can map a type to an instance. This is what you need. http://spirit.sourceforge.net/dl_more/fusion_v2/libs/fusion/doc/html/fusion… http://spirit.sourceforge.net/dl_more/fusion_v2/libs/fusion/doc/html/fusion… Any comments are appreciated, Perhaps this is a known design pattern, perhaps there is an easier way of doing this, perhaps there is a boost library which helps with this, Good Luck, Ovanes _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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iostreams and serial ports help
by Rob Desbois 24 Jan '08

24 Jan '08

Hi, I'm a newcomer to boost and having trouble determining if what I want to achieve is possible. I want some sort of boost::iostreams object wrapping a serial port so that it conforms to the usual interfaces - this would be extremely useful not only for its use, but also to enable injection of a stringstream instance as a mock object when testing. It seems that the likely candidate for this is file_descriptor but I'm not entirely sure. First off, file_descriptor refines SeekableDevice, which a serial port isn't - does this mean that I can't do it? After trying to compile I realised that a SeekableDevice provides read, write and seek functions, nothing else. Am I seriously misunderstanding the point of boost::iostreams? If I am then can anybody point me in a better direction? My ultimate requirement is a serial port access class that looks just like a C++/boost iostream. I cannot use C++ iostreams directly as I require access to file-descriptor which is not available. Anyone able to help a lost person please? TIA, --rob

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[function] using with CRTP
by Russell L. Carter 23 Jan '08

23 Jan '08

Hi, This is probably a novice template question. I am curious what I am doing wrong here, where I'm trying to get a function object holding a base member of a CRTP class. gcc 4.2.3 complains about: type/value mismatch at argument 1 in template parameter list for 'template<class Derived> template<template<template<class> class MHBase> template<class Derived> template<class> class MHBase> struct MHBase< <template-parameter-1-1> >::fooFO Any help appreciated! Thanks, Russell #include <boost/function.hpp> #include <iostream> class MHBAccessor { template<class> friend class MHBase; template<class Derived> static int foo(Derived& derived, int i) { return derived.foo_(i); } }; typedef boost::function<int (int)> FooFunc; template <class Derived> struct MHBase { Derived& derived() { return static_cast<Derived&>(*this); } int foo(int i) { return MHBAccessor::foo(this->derived(), i); } template <template <class> class MHBase > struct fooFO { fooFO(MHBase<Derived>& mhb) : mhb_(mhb) {} void operator()(int i) { mhb_.foo(i); } private: MHBase<Derived>& mhb_; }; FooFunc getFooFunc() { FooFunc ff = fooFO<MHBase<Derived> >(*this); return ff; } }; class Put : public MHBase<Put> { friend class MHBAccessor; int foo_(int i) { return i; } }; int main(int argc, char **argv) { Put put; std::cout << put.foo(123) << std::endl; FooFunc ff = put.getFooFunc(); std::cout << ff(456) << std::endl; return 0; }

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