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

boost.serialization question
by Aljaz 27 Feb '08

27 Feb '08

Hello I use boost.serialization for data transfer betwen my server and client applications. The example of serialized data looks like: " 3b22 serialization::archive 4 0 1 2 7 request 1 0 0 1 0 1 2 1 " I've been wondering if there is any way to hide serialization:.archive in the data, maybe replace it with something like 'sa' .. Thanks a lot for help Best regards Aljaz

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Re: [Boost-users] Boost.Test unit testing examples: stale links
by Tim Allison 27 Feb '08

27 Feb '08

To see example 1, use: http://www.boost.org/libs/test/example/unit_test_example_01.cpp The obvious changes are needed for the other examples. (Someone else found these links and posted them at the almost unused forums on SourceForge.) From what I have been able to figure out, the most up to date examples and documentation are found at: http://www.patmedia.net/~rogeeff/html/utf/user-guide.html. I would like to know if you can compile the examples. I can not. I sent an email a week or so ago requesting help compiling the examples with g++. So far, I have not had a response. Tim Allison > ------------------------------ > > Message: 6 > Date: Tue, 26 Feb 2008 22:33:16 +0100 > From: Bram Kuijper <a.l.w.kuijper(a)rug.nl> > Subject: [Boost-users] Boost.Test unit testing examples: stale links > To: boost-users(a)lists.boost.org > Message-ID: <47C4859C.5000302(a)rug.nl> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Hi all, > > I don't know if this is the right place for it, but I wanted to report a > number of stale links on the Boost.Test website. It regards the examples > of the Unit Testing Framework, example 1 to 5 on page > http://www.boost.org/libs/test/doc/examples/index.html > : > > http://www.boost.org/libs/test/doc/examples/unit_test_example1.html > http://www.boost.org/libs/test/doc/examples/unit_test_example2.html > http://www.boost.org/libs/test/doc/examples/unit_test_example3.html > http://www.boost.org/libs/test/doc/examples/unit_test_example4.html > http://www.boost.org/libs/test/doc/examples/unit_test_example5.html > > since I really would like to see some examples of this testing > framework, I wonder if it is possible to have these examples back online? > > thanks, > > Bram Kuijper > >

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[IOStreams] Inconsistency b/w docs and code of stream()
by Nitay Joffe 27 Feb '08

27 Feb '08

Hey guys, I'm working with the boost::iostreams library to create a stream object from a Device class I've implemented. I'm trying to call the constructor that allows setting of the buffer size and it is failing to compile on 64 bit. I used the documenation at http://www.boost.org/libs/iostreams/doc/guide/generic_streams.html#stream The docs say the constructor is of the form: stream(const T& t, std::streamsize buffer_size = default_value, std::streamsize pback_size = default_value); My code to create the stream looks like: MyDevice myDevice(...) MyStream(myDevice, (std::streamsize)500); On a 32 bit machine this works fine, but on a 64 bit one it does not compile. The parameters I'm passing in are not matching up with a constructor in the stream class so it tries to call MyDevice with the wrong set of parameters. I believe the culprit is the file iostreams/detail/push_params.hpp, which defines the buffer and pback size using: #define BOOST_IOSTREAMS_PUSH_PARAMS() \ , int buffer_size = -1 , int pback_size = -1 \ /**/ This macro is then used by stream and friends in their constructor declarations. On 64 bit machines std::streamsize is a long int, so the constructor parameters do not match up and compilation fails. Thanks, -n

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serialization: classes with pimpls
by Noah Roberts 26 Feb '08

26 Feb '08

Any ideas? The only options I can come up with are: 1) break the pimpl idiom by removing the opaqueness or implementing private getter/setter functions for the serialize template. Still get the exception safety of using the pimpl but lose the compile-time decoupling. 2) only implement the serialize function for certain types of archives. This one seems the most interesting actually. 3) write string writers/parsers for serialize to use, which pretty much destroys the whole point of using boost::serialization in the first place. Maybe I'm missing a good option?

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iterator_traits and shared_ptr
by Patrik Jonsson 26 Feb '08

26 Feb '08

Hi, I'm trying to transparently get the type of a shared_ptr or a pod pointer using iterator_traits::value_type. This fails on shared_ptr<T> with the following message: /usr/lib/gcc/x86_64-redhat-linux/4.1.2/../../../../include/c++/4.1.2/bits/stl_iterator_base_types.h: In instantiation of 'std::iterator_traits<boost::shared_ptr<int> >': crap.cc:5: instantiated from here /usr/lib/gcc/x86_64-redhat-linux/4.1.2/../../../../include/c++/4.1.2/bits/stl_iterator_base_types.h:129: error: no type named 'iterator_category' in 'class boost::shared_ptr<int>' /usr/lib/gcc/x86_64-redhat-linux/4.1.2/../../../../include/c++/4.1.2/bits/stl_iterator_base_types.h:131: error: no type named 'difference_type' in 'class boost::shared_ptr<int>' It seems shared_ptr needs difference_type and iterator_category for this to work. Is there another way to accomplish what I'm trying to do? Regards, /Patrik

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[variant] make_recursive_variant containing a variant ?
by Alban Linard 26 Feb '08

26 Feb '08

Hi, i am trying to build a recursive variant containing another variant, as described in the following source code: #include <cstdlib> #include <vector> #include <string> #include <boost/variant.hpp> typedef ::boost::variant < int , bool > first_variant; typedef ::boost::make_recursive_variant < first_variant , ::std::string , ::std::vector< ::boost::recursive_variant_ > >::type second_variant; int main() { first_variant f(true); second_variant s(f); return EXIT_SUCCESS; } It does not compile (g++-4.0 and g++-4.3). It seems that the "first_variant" part of second_variant is not used. Why this behavior ? Is there a workaround ? Thanks, Alban Linard

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Boost.Test unit testing examples: stale links
by Bram Kuijper 26 Feb '08

26 Feb '08

Hi all, I don't know if this is the right place for it, but I wanted to report a number of stale links on the Boost.Test website. It regards the examples of the Unit Testing Framework, example 1 to 5 on page http://www.boost.org/libs/test/doc/examples/index.html : http://www.boost.org/libs/test/doc/examples/unit_test_example1.html http://www.boost.org/libs/test/doc/examples/unit_test_example2.html http://www.boost.org/libs/test/doc/examples/unit_test_example3.html http://www.boost.org/libs/test/doc/examples/unit_test_example4.html http://www.boost.org/libs/test/doc/examples/unit_test_example5.html since I really would like to see some examples of this testing framework, I wonder if it is possible to have these examples back online? thanks, Bram Kuijper

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Re: [Boost-users] boost exceptions on MacOS 10.5
by David Thulson 26 Feb '08

26 Feb '08

Hello, I have had similar problems in OSX 10.5 where exceptions are not caught, but with a different project. We are using CMake. I'm not sure how familiar you are with CMake, but it is a build system that allows you to generate projects for "native" development tools. In OSX, you can create Xcode projects or makefiles. If I use Xcode to build the project, I cannot catch exceptions consistently. If I use makefiles, it works fine. You can see the discussion on the CMake list here: http://www.cmake.org/pipermail/cmake/2008-January/019091.html The compiler flags that are used are significantly different, so that seems like a likely problem. Unfortunately, I have not had time to finish tracking the issue down. I'm not really familiar with building boost so maybe this is obvious, but how are you building it? What compiler flags are you using? David Thulson

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BGL: ColorMap for depth_first_search
by Christian Sturz 26 Feb '08

26 Feb '08

Hi, I've an urgent question on a BGL algorithm. I want to use the depth_first_search algorithm from the Boost Graph Library. However, I've problems with the definition of my own ColorMap. To illustrate this, here is an example (taken from http://www.boost.org/libs/graph/example/dfs-example.cpp) int main() { // Select the graph type we wish to use typedef adjacency_list < vecS, vecS, directedS > graph_t; typedef graph_traits < graph_t >::vertices_size_type size_type; // Set up the vertex names enum { u, v, w, x, y, z, N }; char name[] = { 'u', 'v', 'w', 'x', 'y', 'z' }; // Specify the edges in the graph typedef std::pair < int, int >E; E edge_array[] = { E(u, v), E(u, x), E(x, v), E(y, x), E(v, y), E(w, y), E(w, z), E(z, z) }; graph_t g(edge_array, edge_array + sizeof(edge_array) / sizeof(E), N); // Typedefs typedef boost::graph_traits < graph_t >::vertex_descriptor Vertex; typedef size_type* Iiter; // discover time and finish time properties std::vector < size_type > dtime(num_vertices(g)); std::vector < size_type > ftime(num_vertices(g)); size_type t = 0; dfs_time_visitor < size_type * >vis(&dtime[0], &ftime[0], t); // Some arbitrary vertex as root (start point of DFS) Vertex root = source( edge_array[2],g ); depth_first_search(g, visitor(vis), myColorMap, root ); return 0; } My problem is the definition of "myColorMap" which must be a model of Read/Write Property Map. However, I have no idea how to define a working ColorMap. It would be fully sufficient to take the default color map which is used when DFS is invoked with "depth_first_search(g, visitor(vis));" Do you have an idea how I define a ColorMap that I can use for "myColorMap"? Any help is appreciated. Thank you. Christian -- Psst! Geheimtipp: Online Games kostenlos spielen bei den GMX Free Games! http://games.entertainment.web.de/de/entertainment/games/free

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[noob] I have pointer, ptr_list::release wants iterator
by Szczepan Hołyszewski 26 Feb '08

26 Feb '08

I have a pointer to an object that is in a ptr_list, and I want to "detach" the object from the list without deleting it. Problem: ptr_list::release() wants an iterator, not a pointer. A naive attempt at std::finding the iterator fails because ptr_list's indirection kicks in and std::find ends up wanting to compare values instead of pointers. Luckily my objects aren't equality comparable so I get a compile error instead of an elusive bug. As a workaround I just walk the list with BOOST_FOREACH() but it feels kludgy. Is there a "designed" way to feed a ptr_list an element pointer and milk the corresponding iterator? Is there a direct way do detach an item from ptr_list without deleting it? Did I overlook something obvious? Thanks in advance, Szczepan Holyszewski

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