September 2009 - Boost-users

date_time formatting issues
by ariasgore＠gmx.de 04 Sep '09

04 Sep '09

Hi, I have been trying to format a simple posix date time for string representation. The basic part is plain and simple: ---------------------------------------------- #include <boost/date_time/posix_time/posix_time.hpp> namespace ps = boost::posix_time; ps::ptime t(ps::second_clock::local_time()); std::string foo = ps::to_simple_string(t); ---------------------------------------------- But how can I format this returned string? I think the facets are required but as mentioned here : http://www.boost.org/doc/libs/1_40_0/doc/html/date_time/date_time_io.html#d… I tried something with the boost::date_time::date_input_facet: e.g ---------------------------------------------- ps::date_input_facet("%A"); ps::ptime t(ps::second_clock::local_time()); std::string foo = ps::to_simple_string(t); ---------------------------------------------- by using it before the simple_string call. I am sure this is wrong but I wouldn't like to use streams in addition to that to simply rearange some parts of a date for that reason. thanks sam -- Jetzt kostenlos herunterladen: Internet Explorer 8 und Mozilla Firefox 3 - sicherer, schneller und einfacher! http://portal.gmx.net/de/go/chbrowser

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[Boost-Serialization] Problem with BOOST_CLASS_EXPORT
by Soumen 03 Sep '09

03 Sep '09

Hi, I'm getting conflicting declaration with BOOST_CLASS_EXPORT and I think I've got the reason. But I'm not aware of clean solution to overcome this. Let me explain the problem here. Say in FileAB.h, I've class A, class B defined. I've a FileSExportAB.h where I've BOOST_CLASS_EXPORT(A) at line say 10 and BOOST_CLASS_EXPORT(B) at line 11. Similarly I've class C and class D defined FileCD.h. And FileSExportCD.h has BOOST_CLASS_EXPORT(C) @ line 10 and BOOST_CLASS_EXPORT(D) @ line 11. And while building, I get error like following: ------------------------------------------------------------------------------------------------ FileSExportCD.h:10: error: conflicting declaration ‘const boost::archive::detail::guid_initializer<C>& <unnamed>::boost_serialization_guid_initializer_10’ FileSExportAB.h:10: error: ‘<unnamed>::boost_serialization_guid_initializer_10’ has a previous declaration as ‘const boost::archive::detail::guid_initializer & <unnamed>::boost_serialization_guid_initializer_10’ ------------------------------------------------------------------------------------------------ All A, B, C and D are in same namespace. Putting things at different namespace is overkill on legacy code. Is using BOOST_CLASS_EXPORT_GUID only better solution? Is it not pssible for boost to resolve it automatically with BOOST_CLASS_EXPORT macro? Regards, ~ Soumen -- View this message in context: http://www.nabble.com/-Boost-Serialization--Problem-with-BOOST_CLASS_EXPORT… Sent from the Boost - Users mailing list archive at Nabble.com.

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cycle iterators
by Neal Becker 03 Sep '09

03 Sep '09

I use these regularly. Work for me.

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[iterator_adaptor] Does the base need a const version of operator* ?
by Andre Massing 03 Sep '09

03 Sep '09

Hi, I am trying to wrap our kind of iterators (for meshes) with the iterator_adaptor class template, something like class CellBoostIterator : public boost::iterator_adaptor< CellBoostIterator //Derived , CellIterator //Base , Cell //Value , boost::forward_traversal_tag // CategoryOrTraversal > { ... }; Since the base class CellIterator already provides a operator* and a operator-> (both non-const version) I did not redefine any of these within the CellBoostIterator class. If I now want to use with code-snippet typedef Mesh_2::CellBoostIterator MIT; MIT mit; Mesh_2 mesh_2(omega1); for (MIT mit = mesh_2.begin(); mit != mesh_2.end(); ++mit) { std::cout << mit->index() <<std::endl; } I get a compile error /usr/include/boost/iterator/iterator_adaptor.hpp:312: error: passing ‘const dolfin::CellIterator’ as ‘this’ argument of ‘dolfin::Cell& dolfin::CellIterator::operator*()’ discards qualifiers I looked at the corresponding line /usr/include/boost/iterator/iterator_adaptor.hpp:312: typename super_t::reference dereference() const { return *m_iterator; } So it seems to me that I have to provide a const version of operator*, or do I get something wrong? I am a bit confused, since I have not found this kind of requirements in the documentation. Any enlightening, hints or pointers are greatly appreciated! Greetings, Andre

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BGL new graph type implementation trouble
by Sebastian Weber 03 Sep '09

03 Sep '09

Hi! I am currently trying to implement a new graph type which I want to use with the BGL. The graph implements the Incidence Graph concept and should work out of the box with DFS algorithm of the BGL. However, I had to find out that the edge_descriptor must obey an EqualityComparison concept which keeps DFS from compiling. My current edge_descriptor is just a typedef to std::pair<vertex_descriptor, vertex_descriptor>. The vertex_descriptor itself is a custom object I wrote myself. Another problem turns out to appear with the copy-graph algorithm. This algorithm tries to copy vertex_all-property maps and edge_all property maps which I simply do not have defined in my custom graph as I only support the vertex_index mechanism. So what to do here? How can I tell copy-graph that these maps are not existent? Any help would be great here as I have the impression to hit limits of the documentation (the Equality-thing is not mentioned in the docs, at least I did not find it...). Greetings, Sebastian

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compile boost thread lib for iphone failed! the darwin g++ cant find head files for STL (string, cstddef)..how to solve this problem?
by terryc tang 03 Sep '09

03 Sep '09

i do the work as following: 0.install bjam 1. down boost_1_40_0 2. untar to disk root directory 3. ./bootstrap.sh ---with-library=thread 4. configure user-config.jam as following: using darwin : 4.2.1~iphone : /Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/g++ : <striper> : <architecture>arm <target-os>iphone <macosx-version>iphone-2.1 ; using darwin : 4.2.1~iphonesim : /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/g++ : <striper> : <architecture>x86 <target-os>iphone <macosx-version>iphonesim-2.1 ; 5. command at console: bjam --prefix=/usrLibs/boostiPhoneDev toolset=darwin architecture=arm target-os=iphone macosx-version=iphone-2.1 define=_LITTLE_ENDIAN link=static install ... ... .... .. Any setting missing ? how to deal with it? In file included from ./boost/config.hpp:40, from ./boost/thread/detail/config.hpp:10, from libs/thread/src/pthread/thread.cpp:8: ./boost/config/select_stdlib_config.hpp:17:19: error: cstddef: No such file or directory In file included from ./boost/config/select_stdlib_config.hpp:33, from ./boost/config.hpp:40, from ./boost/thread/detail/config.hpp:10, from libs/thread/src/pthread/thread.cpp:8: ./boost/config/no_tr1/utility.hpp:21:21: error: utility: No such file or directory In file included from ./boost/thread/pthread/thread_data.hpp:9, from ./boost/thread/thread.hpp:17, from libs/thread/src/pthread/thread.cpp:10: ./boost/thread/exceptions.hpp:19:18: error: string: No such file or directory ./boost/thread/exceptions.hpp:20:21: error: stdexcept: No such file or directory In file included from ./boost/smart_ptr/shared_ptr.hpp:27, from ./boost/shared_ptr.hpp:17, from ./boost/thread/pthread/thread_data.hpp:10, from ./boost/thread/thread.hpp:17,

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[proto] char vs. int behaviour when matching
by Maurizio Vitale 03 Sep '09

03 Sep '09

Proto behaves in a different way when matching terminal<char> and terminal<int>. The only difference I'm aware is that it is implementation defined whether 'char' means 'signed char' or 'unsigned char' but it has to mean one of the two. I was surprised to hit the following: struct char_grammar : proto::or_< proto::terminal<signed char>, proto::terminal<unsigned char> > {}; struct extended_char_grammar : proto::or_< proto::terminal<char>, proto::terminal<signed char>, proto::terminal<unsigned char> > {}; struct int_grammar : proto::or_< proto::terminal<signed int>, proto::terminal<unsigned int> > {}; int main() { // WHY _NOT? BOOST_MPL_ASSERT_NOT ((proto::matches<proto::terminal<char>, char_grammar>)); BOOST_MPL_ASSERT ((proto::matches<proto::terminal<char>, extended_char_grammar>)); // GIVEN THAT: BOOST_MPL_ASSERT ((proto::matches<proto::terminal<int>, int_grammar>)); return 0; } Is this behaviour intentional? Regards, Maurizio

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[Unordered] [Multi-Index] Set lookup from something else than key_type
by Dominique Devienne 02 Sep '09

02 Sep '09

We currently have a unordered_map< Uid, shared_ptr<Identity> >, where Identity already contains the Uid. So I thought I could avoid the duplicated Uid by using an unordered_set< shared_ptr<Identity>, MyHash, MyPred > to hash/compare by the internal Uid, but unlike a Multi-Index hashed_index [1], unordered doesn't seem to provide: "lookup operations accepting search keys different from the key_type of the index, which is a specially useful facility when key_type object are expensive to create." Any reason why unordered cannot allow similar "compatible key" lookups? What kind of overhead is there (memory use, runtime), if any, in using Multi-Index as opposed to unordered_set in this scenario? Using Multi-Index yields a more complex type and slower compiles it seems due to its meta-programming uses I guess. Thanks for any insight. --DD [1] http://www.boost.org/doc/libs/1_40_0/libs/multi_index/doc/tutorial/basics.h…

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Boost::bind: compiling error from sample code in book
by Boost lzw 02 Sep '09

02 Sep '09

Hi there, I am testing the following sample code on page 264 of the book "Beyond the C++ Standard Library" and got an error msg: "result_type' : is not a member of '`global namespace'' from MSVC 2008 Pro compiler. Can anyone point out what is wrong with it? Thanks. ------------ #include<iostream> #include<string> #include<map> #include<vector> #include<algorithm> #include "boost/bind.hpp" class print_size { typedef std::map<std::string, std::vector<int> > map_type; public: typedef void result_type; result_type operator()(std::ostream& os, const map_type::value_type& x) const { os << x.second.size() << '\n'; } }; int main() { typedef std::map<std::string, std::vector<int> > map_type; map_type m; m["Strange?"].push_back(1); m["Strange?"].push_back(2); m["Wierd?"].push_back(3); m["Wierd?"].push_back(4); m["Wierd?"].push_back(5); std::for_each(m.begin(), m.end(), boost::bind(&print_size(), boost::ref(std::cout), _1)); } ------------

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[GIL] GIL and FreeImage interaction sample code suggestions ?
by Nicolas Lelong 02 Sep '09

02 Sep '09

Hi, FWIW I'm considering boost GIL to implement the few image algorithms I need, and I need proper image I/O on top of that. As I'm using FreeImage in my current codebase, I thought about exposing FreeImage image memory layout to GIL. You can find the, quite simplistic, source code here : http://code.google.com/p/rotoglup-scratchpad/source/browse/trunk/rtgu/image… http://code.google.com/p/rotoglup-scratchpad/source/browse/trunk/rtgu/image… http://code.google.com/p/rotoglup-scratchpad/source/browse/trunk/rtgu/image… I created a 'borrowed_image' class that mimics the behaviour of gil::image : it is not allocating memory itself, it takes an existing memory buffer and a 'deleter' (under the form of a boost::shared_ptr<void>) as input. This allows to use directly the memory allocated by FreeImage, avoiding extra copy, in case of file input. Feel free to use the code as a starting point, if you have similar needs, and I'd be glad to have comments about the concept of 'borrowed_image' class, and about its interface, as I feel I'm missing something. Cheers, Nicolas.

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