August 2009 - Boost-users - lists.boost.org

how to know my own IP address
by Paolo Viotti 14 Aug '09

14 Aug '09

Hi, I'm using the boost library to create and manage a UDP socket. I was wondering if there is a way to know the public address of my machine using the boost classes. With this code udp::endpoint thisendpoint(udp::v4(), UDPPORT); boost::asio::ip::address myaddress = thisendpoint.address(); std::cout<< "__My IP address: " << myaddress.to_string() << std::endl; I can only print the any_address (0.0.0.0)... thanks, p_viotti

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randomize_property question
by mcorbion＠mobigis.fr 14 Aug '09

14 Aug '09

Hello I'm currently trying to create a randomly made graph and I'm having problem populating the properties using the randomize_property. Just like this man http://lists.boost.org/boost-users/2005/09/14033.php I'm wondering if it's even possible to use randomize_property with the bundled properties? I hope so because the bundled properties are in my opinion much more easy to use. Here's the bundled property I would like to randomize (which is quite basic): struct City { int pos_X; int pos_Y; }; I've tried to get from it the property class needed using vertex_bundle_type<Graph>::type this way : randomize_property<vertex_bundle_type<Graph>::type>(m_Graph,l_Gen); I then looked in the source code and it seems that the function merely takes a property_map and randomly changes the values. So I tried this (I was desperate^^) using the way "get" works with bundled property : randomize_property<&City::pos_X>(m_Graph,l_Gen); Here's the source code for randomize_property boost/graph/random.hpp 169 template<class Property, class G, class RandomGenerator> 170 void randomize_property(G& g, RandomGenerator& rg, 171 Property, vertex_property_tag) 172 { 173 typename property_map<G, Property>::type pm = get(Property(), g); 174 typename graph_traits<G>::vertex_iterator vi, ve; 175 for (tie(vi, ve) = vertices(g); vi != ve; ++vi) { 176 pm[*vi] = rg(); 177 } 178 } I know that for my short example and, by inspiring me from the source, I could do it manually but I'd rather do it using genericity. Hope there isn't too much broken english. Thanks M.Corbion

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[Program options] changing output format of options_description
by Roman Shmelev 14 Aug '09

14 Aug '09

Hi! I'm using boost::program_options and my program obtains many parameters. When name or default value of param is long, I get smth like this while trying to cout << desc_obj; fullname-of-important-file, f (=/fold1/fold2/fold3/file.ext) The description if so narrow :( And I wish if it was like this: fullname-of-important-file, f (=/fold1/fold2/fold3/file.ext) The description is here. Such formatting is much more beautiful, IMHO. [empty line?] another-param (=value) Another long long long long description Is there any way to do this? some switcher..

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minor boost::interprocess::vector bug (?)
by Bob Walters 13 Aug '09

13 Aug '09

I have encountered a minor bug with boost::interprocess::vector<> which involves a situation where std::uninitialized_copy() is invoked with a NULL pointer value, and length of 0. I’m not sure if that is truly an error, but unfortunately the MWVC (9.0) debug library has an assertion which gets tripped by the null pointer value, so I've had little choice but to patch my copy of the code to prevent that call from happening. Let me know if you want me to create a trac item for this problem. The problem occurs when an empty vector (created by the single allocator argument constructor) is swapped with a vector that has an established capacity. Specifically, I see this with the following code: boost::interprocess::vector<char,char_alloc_type> *buffer = somewhere_in_shared_memory; // can’t construct ovectorstream to use buffer directly, but can swap it into place: boost::interprocess::basic_ovectorstream< buffer_t<void_alloc_t> > vstream(buffer->get_allocator()); vstream.swap_vector(*buffer); On msvc (9.0), somewhere below priv_range_insert(), a call gets issued to std::uninitialized_copy with a null pointer and length of 0. My solution to this was to modify vector::swap as follows: diff -r ./containers/container/vector.hpp ../../../../boost_1_39_0/boost/interprocess/containers/container/vector.hpp 1206,1208c1206,1210 < this->reserve(new_size); < containers_detail::default_construct_aux_proxy<T, T*, size_type> proxy(n); < priv_range_insert(this->cend().get_ptr(), n, proxy); --- > if (n>0) { > this->reserve(new_size); > containers_detail::default_construct_aux_proxy<T, T*, size_type> proxy(n); > priv_range_insert(this->cend().get_ptr(), n, proxy); > } Again, let me know if you want me to create a ticket for this problem.

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[statechart] Can inner states be defined for a state in orthogonal region?
by Gordon Smith 13 Aug '09

13 Aug '09

I'm unable to compile the machine below that includes inner states within a state in an orthogonal region. The error is: use of undefined type 'boost::STATIC_ASSERTION_FAILURE<x>' {{{ struct SerialPort : public state_machine< SerialPort, StateTXWrapper > {} struct StateTXWrapper: simple_state< StateTXWrapper, SerialPort, mpl::list< StateTXNotReady, StateStart > > {}; // Orthogonal 0 struct StateMrf : simple_state< StateMrf, StateTXWrapper::orthogonal< 0 > > {}; struct StatePortClosed : simple_state< StatePortClosed, StateTXWrapper::orthogonal< 0 > > {}; struct StateOpenPort : simple_state< StateOpenPort, StatePortClosed > {}; struct StateOpenPortWait : simple_state< StateOpenPortWait, StatePortClosed > {}; }}} The assert is invoked for StateOpenPort and StateOpenPortWait: BOOST_STATIC_ASSERT( ( mpl::less< orthogonal_position, typename context_type::no_of_orthogonal_regions >::value ) ); Is it possible to have such inner states? Boost version 1.38 Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 15.00.30729.01 for 80x86

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[serialization - newbie] serializing/deserializing singleton class objects
by Soumen 13 Aug '09

13 Aug '09

Hi, This is query was posted as part of different question. Doing a fresh post with a new topic as earlier one didn't fetch any response - assuming it may got lost in the original context. I'm trying to serialize/deserialize singleton class objects. My code is similar to following for save/restore: void save(boost::archive::binary_oarchive &archive) { MyData *data = MyData::instance(); if (data) archive << data; } void restore(boost::archive::binary_iarchive &archive) { MyData::cleanup(); archive >> (MyData *) MyData::instance(); } My save function works - stores data on disk. But the restore function doesn't compile. I get error like following: error: no match for ‘operator>>’ in ‘archive >> (MyData *) MyData::instance()’ /boost/1_35_0/include/boost/archive/detail/interface_iarchive.hpp:62: note: candidates are: Archive& boost::archive::detail::interface_iarchive<Archive>::operator>>(T&) [with T = MyData*, Archive = boost::archive::binary_iarchive] If I change the 2nd line of restore function in following way, the error message almost remains same: MyData *inst = MyData::instance(); archive >> (MyData *) inst; Please guide me what I'm doing wrongly. Regards, ~ Soumen -- View this message in context: http://www.nabble.com/-serialization---newbie--serializing-deserializing-si… Sent from the Boost - Users mailing list archive at Nabble.com.

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Re: [Boost-users] question about multi_array use
by Alle Meije Wink 13 Aug '09

13 Aug '09

> On Sat, Aug 8, 2009 at 4:51 PM, Alle Meije Wink<a.m.wink(a)gmail.com> wrote: > >>> You could always just wrap up each of the possible dimensions in a >>> struct that can handle the (de)serialization and everything too, >>> perhaps use crtp to put identical functionality in a non-virtual base >>> class. > >> Overmind, I guess compared to what I had in mind (define the data container >> of the image [template?] class as a multi_array with a dimensionality given >> as a size_t parameter), the CRTP struct you are talking about specifies all >> of the possible types. Is that correct? >> >> If I understand it correctly then this does what I want, but does that mean >> that in the worst-case scenario, I have to write out the functionality for >> all different dimensionalities? If the parameterised template class idea is >> possible, that would save some typing! > > I could see using fusion (mostly the "apply" construct) would make it > generic to any number of dimensions. Boost.Fusion is amazing for such > work, think MPL, but it works at runtime too. > I like the look of boost::Fusion in terms of advanced generic C++ programming, but in terms of finding a concise description of my image template class / class / data type, this may be overshooting the aim a bit. Plus I will need to read up on template metaprogramming! Coming back to the original idea: my images are stored as files which have a (on-disc 1-dimensional) sequence of intensities, and a header containing a number dims (dimensionality) and an array dim[8] (maximum of 8 dimensions). The problem that images can have different (but all built-in) data types can be circumvented with template programming, which is great compared to the old C-style casting to double. But talking about C-style, dealing with dimensions was possible in a fast way (in terms of both coding and runnning) with malloc and pointers (to pointers (to pointers)). Previously this is how I used to implement operations on images: casting everything to double, using pointers to get to image elements. I was hoping that by using templates to abstract from element type, and multi_array to cover different dimensionalities, it would be possible code image operations only once, for all types and dimensionalities. From what I understand, the curious recursion way matches most closely what I was looking for (and is still as close to generic programming as possible?). The scopira narray class http://www.scopira.org/api/narray_8h-source.html seems to do something similar. If there is another way to do this then I'm still very interested! Thanks, Alle Meije

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Re: [Boost-users] question about multi_array use
by Alle Meije Wink 13 Aug '09

13 Aug '09

Dear OverMind Hope I'm not making this thread too long, I've tried to search the archives but did not get further than browsing. After looking at different options, your idea of wrapping the different dimensions/dimensionalities in a struct sounds like the best idea, and closest to the type of data and problems I'm dealing with. Would you have a few more clues (maybe code, maybe URLs) as to how to shape this? I had a look at http://en.wikipedia.org/wiki/Curiously_recurring_template_pattern but that is a very broad description. As I understand it, the struct that encapsulates the possible dimensionalities and the CRTP class refer to the same solution? Or are they different things? Thanks! Alle Meije > Date: Fri, 7 Aug 2009 18:09:11 -0600 > From: OvermindDL1 <overminddl1(a)gmail.com> > Subject: Re: [Boost-users] question about multi_array use > > You could always just wrap up each of the possible dimensions in a > struct that can handle the (de)serialization and everything too, > perhaps use crtp to put identical functionality in a non-virtual base > class. > >> On Fri, Aug 7, 2009 at 2:04 PM, Anton Daneyko<self(a)mezhaka.com> wrote: >> Hello, >> >> I might be wrong, but it seems the answer is "no you can't do that", because >> the dimensionality is a template parameter multi_array<int, 2> and >> multi_array<int, 3> are different types. However I would like to hear some >> else' opinion as well. >> >> Regards, >> Anton Daneyko. >> >> On Fri, Aug 7, 2009 at 3:48 PM, Alle Meije Wink <a.m.wink(a)gmail.com> wrote: >>> Hello, >>> >>> I would like to use the multi_array container to handle imaging data. The >>> image data can be anything up to 8-dimensional (usually up to 4) and >>> dimension information is found in records that accompany the binary data. >>> >>> Would it be possible to create an image class that takes the >>> dimensionality and extents list as parameters, so that images of all >>> dimensionalities can be treated as one class? >>> >>> For example, could the dimensionality be passed as a size_t argument? >>> >>> What I understand from the multi_array paper is that the extents list >>> would only be required whan the array is initialised.

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[BGL] Does put override const?
by Caligula 13 Aug '09

13 Aug '09

In the code snippet below (which is inside a vis object) if the line //g[*ei].edge_Weight = "Heavy"; is uncommented, compiling gives :error const discarded ( or something to that effect) because of the const in (const Graph & g) . But then how come put(m_eWeight_map, *ei, "Heavy"); compiles successfully and successfully changes the value? Does put(m_eWeight_map, *ei, "Heavy"); override the const in void Change_data(const Graph & g) ? template < typename Graph > void Change_data(const Graph & g) //void Change_data(Graph & g) { typename graph_traits< Graph >::edge_iterator ei, ei_end; for(tie(ei, ei_end) = edges(g); ei != ei_end; ++ei) { put(m_eWeight_map, *ei, "Heavy"); //g[*ei].edge_Weight = "Heavy"; } } Thanks - Caligula

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What's the status of boost.chrono?
by Tan, Tom (Shanghai) 13 Aug '09

13 Aug '09

Back in May, Vicente Botet Escriba volunteered to take up this library when Beman dropped it. What's the status now? I really like and use the process_clocks and timers alot, which seems not be in the c++0x standard library. When can we have it in the boost trunk so that we can build it with a boost release? Thanks.

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