January 2012 - Boost-users - lists.preview.boost.org

Accessing exterior graph properties by name
by David Doria 26 Jan '12

26 Jan '12

Is there a way to "associate" an external property map to a name so that it can be retrieved from the graph? With a standard interior property, you can do: // Declare that you will be able to identify a property map by "vertex_data" namespace boost { enum vertex_data_t { vertex_data }; BOOST_INSTALL_PROPERTY(vertex, data); }; // Get the vertex_data property map from the graph typedef boost::property_map<Graph, boost::vertex_data_t>::type PropertyMapType; PropertyMapType propertyMap = get(boost::vertex_data, g); However, with the exterior properties, I can associate the property map with the nodes of the graph: typedef boost::property_map<GraphType, boost::vertex_index_t>::const_type indexMapType; indexMapType indexMap(get(boost::vertex_index, graph)); boost::vector_property_map<float, indexMapType> myMap(100, indexMap); but how would I then be able to, only having the graph object, get this map? That is, there was never any name, like "vertex_data" introduced in this case. Thanks, David

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was it created or opened when using boost::interprocess::shared_memory_object?
by Gehua Yang 26 Jan '12

26 Jan '12

Dear folks, I have been using Boost's Interprocess module for communication between several peer processes. In particular, I am using the shared_memory_object. As I was trying to create it with open_or_create_t flag (to ensure it finishes in an atomic operation), I cannot tell whether it was created or it was just opened. I would like to apply initialization when it was created but use its current information when it was opened. I hope there is a member function that can return this status. Best regards, Gehua Yang

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[BOOST USERS] [ BGL ] [GRAPH ] iterating through the vertices and edges of a filter graph
by srinivas boppu 26 Jan '12

26 Jan '12

Hello All, I need a small help in iterating through the vertices and edges of a filtered graph. Here is some sample code of the filtered graph. ( http://programmingexamples.net/wiki/CPP/Boost/BGL/FilteredGraph) ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- #include <iostream> #include <boost/graph/adjacency_list.hpp>#include <boost/array.hpp>#include <boost/graph/filtered_graph.hpp>#include <boost/graph/graph_utility.hpp> template <typename TGraph>struct vertex_id_filter{ bool operator()(const typename boost::graph_traits<TGraph>::vertex_descriptor& v) const { return 3 < v; // keep all vertx_descriptors greater than 3 }}; int main(){ using namespace boost; typedef adjacency_list<vecS, vecS, directedS, no_property, property<edge_weight_t, int> > Graph; typedef property_map<Graph, edge_weight_t>::type EdgeWeightMap; unsigned int numberOfVertices = 10; Graph g(numberOfVertices); for(unsigned int i = 0; i < numberOfVertices - 1; ++i) { add_edge(i, i+1, g); } std::cout << "Original graph:" << std::endl; boost::print_graph(g); vertex_id_filter<Graph> filter; filtered_graph<Graph, boost::keep_all, vertex_id_filter<Graph> > filteredGraph(g, boost::keep_all(), filter); // (graph, EdgePredicate, VertexPredicate) std::cout << "Filtered graph:" << std::endl; boost::print_graph(filteredGraph); return 0;} ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Here is my question. How do I iterate through the vertices and edges of "filteredGraph". I wanted to use the functions vertices( filteredGraph) and edges(filteredGraph) seems that we cannot use these functions as in the case of filtered graphs they return filtered_iterators. Please, can some one extend the above example and show me how to iterate through the vertices and edges. Thanks and Regards, Srinivas Boppu

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Ticket 4787 / Udp control headers.
by amit khandelwal 26 Jan '12

26 Jan '12

I was going through the 1.48 source code and I don't see it there. Is there a plan to add this patch or was it rejected due to some reason? Thanks, Amit Khandelwal

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boost filesystem
by John Emmas 26 Jan '12

26 Jan '12

Hello, I hope someone here will be able to help with this. Sorry, but the background is a little long-winded.... I've just discovered to my dismay that Microsoft's implementation of fstream, ifstream and ofstream are fatally flawed. I'm not sure if these characters will display correctly across this mailing list but consider the following character set:- ΔΗΜΗΤΡΗΣ which is apparently the Greek name "Dimitris". In an English locale, the following path would only be considered valid (by Windows) in a Unicode environment:- C:/Users/ΔΗΜΗΤΡΗΣ/some_file_name That's fine - because the user name doesn't contain valid English characters. However in Greece, that same path should qualify as a valid, non-Unicode file path and should therefore be openable without needing Unicode. For example, when building with MSVC this works:- #include <fcntl> int file = _open("C:/Users/ΔΗΜΗΤΡΗΣ/some_file_name", _O_RDONLY); However, this fails to work - even though it uses the same path:- #include <fstream> using std::fsrream; fstream file("C:/Users/ΔΗΜΗΤΡΗΣ/some_file_name", fstream::in | fstream::out); To cut a long story short, I noticed that libboost offers its own 'filesystem' implementation. Does boost::filesystem implement its own fstream, ifstream and ofstream? If so, would they likely suffer from the same problem (on Windows). If not, where can I find some examples of using boost::filesystem? Thanks, John

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[interval][units] interval operators not working when inteval elements are quantities
by alfC 26 Jan '12

26 Jan '12

Hi, Does anybody know what is missing in the boost.interval (or in the boost.units) to allow these operation. It seems that there is no other way than to make "interval/arith.hpp:operator/" more generic. -- Thanks, Alfredo #include<boost/units/systems/si.hpp> #include "alf/boost/units/interval.hpp" int main(){ boost::numeric::interval<double> iv(1.,10.); clog << iv << " " << 1./iv << endl; // ok, gives [1., 10] and [0.1,1.] boost::numeric::interval<quantity<si::length> > iv2(1.*si::meter, 10.*si::meter); clog << iv2 << " " << 1./iv2 << endl; // error: no match for ‘operator/’ in ‘1.0e+0 / iv2’ return 0; }

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FW: adjacency lists
by Neiderer, Andrew M CIV (US) 26 Jan '12

26 Jan '12

tried with https://svn.boost.org/svn/boost/trunk/boost/graph/adjacency_list_io.hpp but getting during translation. Thank you for your time. __________________________________________________________________________________________________________________________________________________________________________ > From: boost-users-bounces(a)lists.boost.org [boost-users-bounces(a)lists.boost.org] on behalf of Jeremiah Willcock [jewillco(a)osl.iu.edu] > Sent: Thursday, January 19, 2012 10:36 AM > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] adjacency lists > > On Thu, 19 Jan 2012, Neiderer, Andrew M CIV (US) wrote: > > > > > This is about 1/4 of error message. I think if this is addressed then rest of errors will go away. > > > > > > > > Result of > > > > $g++ -I home/neiderer/src/C++/boost_1_48_0 -c adjacency_list_io.cpp > > > > > > > > (I do think you need src since already exists in .../libs/graph/example) > > Please try your code again with the change I just committed to the Boost > trunk (r76588). > > -- Jeremiah Willcock > > > > > > > > > Thank you > > > > ____________________________________________________________________________________________________________________ > > From: boost-users-bounces(a)lists.boost.org [boost-users-bounces(a)lists.boost.org] on behalf of Jeremiah Willcock > > [jewillco(a)osl.iu.edu] > > Sent: Thursday, January 19, 2012 9:27 AM > > To: boost-users(a)lists.boost.org > > Subject: Re: [Boost-users] adjacency lists > > > > On Thu, 19 Jan 2012, Neiderer, Andrew M CIV (US) wrote: > > > > > > > > I am still learning graphs, BGL 1.48.0 so beginner questions: > > > > > > > > > > > > 1. not sure what adjacency list/matrix are used for other than building a graph > > > > > > for traversal. Or maybe this is it? > > > > That is what they are used for -- to build and represent graphs. > > > > > > > > > > > > > > 2. I need to build a sparse network. So I am using adjacency_list_io.cpp by Francois Faure (2001). > > > > > > In this example I can read(g2), but when outputting > > > > > > > > > > > > std::cout << write(g2) > > > > > > > > > > > > I get lots of translation errors :-( > > > > > > > > > > > > I know I do not give details here but maybe someone could guess a -D??? to make > > > > > > adjacency_list_io.hpp happy. > > > > > > (The read(g2) works fine) > > > > > > > > > > > > Or I can certainly provide some of the error message. > > > > Could you please provide that? I am not familiar with that code. > > > > > > > > > > > > > > Also has Dr. Nick Edmonds completed (or near completion) of "active-message" based release (MPI)? > > > > We are still working on the paper based on that code. A release is likely > > to be within the next couple of months, but nothing is certain yet. > > > > -- Jeremiah Willcock > > > > > >

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[BGL] question about connected_components()
by Andriy Gapon 25 Jan '12

25 Jan '12

This page: http://www.boost.org/doc/libs/1_48_0/libs/graph/doc/connected_components.ht… says "The connected_components() functions compute the connected components of an _undirected_ graph using a DFS-based approach." [emphasis mine] Looking here: http://www.boost.org/doc/libs/1_48_0/boost/graph/connected_components.hpp I see somewhat some unexpected things. o Only the first variant asserts that the graph is undirected, in the second variant the assert is commented out - why is that? o Both variants use depth_first_search() and not undirected_dfs(), which would seem to be more logical for the undirected case - why? Despite the above questions I actually want to use connected_components() [and not strong_components()] for a directed graph. Should that be possible? Does it make sense? Thank you! -- Andriy Gapon

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d_ary_heap_indirect problem
by David Doria 25 Jan '12

25 Jan '12

I am trying to use d_ary_heap_indirect. I was able to create an object of the queue, but I can't push a vertex into it. Here is what I tried: http://programmingexamples.net/wiki/CPP/Boost/BGL/d_ary_heap_indirect I get a "no match for operator[]" error on the last line (the push()). Can anyone see what is wrong with that example? Thanks, David

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~optional<int> generates unnessesary code
by Hite, Christopher 25 Jan '12

25 Jan '12

The problem is that m_initialized is checked and set during deconstruction. This generates a bunch of useless code for types with trivial deconstruction: if(m_initialized){ // do nothing m_initialized = false; } The code is more than useless since it contains a branch. In my case I've got a big object I would expect to die without peep, branching and writing to memory for no reason. The steps below show what gcc 4.6.0 generates. You'd expect the function to do nothing. Boost optional has no obligation to maintain state during deconstruction (otherwise you'd need states for deconstructing,constructing). It's not responsible for the bytes left behind after deconstruction. By the way boost::variant does do this correctly. Chris ------------------ #include <boost/optional.hpp> typedef boost::optional<int> optional_int; void deconstruct_boost_optional(optional_int& o){ o.~optional_int(); } ------------------ objdump -f -d -C -l boost_optional_deconstruction.o |c++filt 00000000 <deconstruct_boost_optional(boost::optional<int>&)>: deconstruct_boost_optional(boost::optional<int>&)(): /home/eh2hite/chris/src_root/src/test/boost_optional_deconstruction.cpp:5 0: 8b 44 24 04 mov 0x4(%esp),%eax boost::optional_detail::optional_base<int>::destroy()(): /usr/local/include/boost/optional/optional.hpp:407 4: 80 38 00 cmpb $0x0,(%eax) 7: 74 03 je c <deconstruct_boost_optional(boost::optional<int>&)+0xc> boost::optional_detail::optional_base<int>::destroy_impl(mpl_::bool_<false>)(): /usr/local/include/boost/optional/optional.hpp:434 9: c6 00 00 movb $0x0,(%eax) c: f3 c3 repz ret

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BGL defining my own iterator?
by Anders Wallin 24 Jan '12

24 Jan '12

Hi all, For traversing the faces of a planar BGL graph I store 'next' pointers in a bundled property for each edge. I can go round a face of the graph like this: BGLGraph g; edge_descriptor current,start; // initialize these! do { // do something with current current=g[current].next; } while(current!=start); Now I was thinking that a lot of 'boilerplate' code would be eliminated if I could do these loops with BOOST_FOREACH. Following the tutorial for iterator_facade I am trying something like this: https://github.com/aewallin/sandbox/blob/master/bgl_iterator/main.cpp However as commented in the code it doesn't quite work. I get either no iterations, one iteration, or all but one edge. Also, holding a pointer to an edge_descriptor in the iterator class doesn't strike me as very elegant, could I store an edge_descriptor directly? suggestions? thanks, AW

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Boost MSM: No transition from submachine to external state
by stetkas 24 Jan '12

24 Jan '12

Using the following example as a template: http://svn.boost.org/svn/boost/trunk/libs/msm/doc/HTML/examples/CompositeTu… http://svn.boost.org/svn/boost/trunk/libs/msm/doc/HTML/examples/CompositeTu… I am trying to create a state machine that consists of an alarm state and a composite state (submachine). When an alarm event is posted while in the composite state, the state machine is supposed to transition to the Alarm state; however, the machine complains that no transition from the composite state on the alarm event exists. This is similar to the example where the player is in playing and a stop event is received. Below is a dumbed-down version of my state machine: http://boost.2283326.n4.nabble.com/file/n4300991/StateMachine.gif Here is the implementation: Here is the output: See anything that could be causing my problem? -- View this message in context: http://boost.2283326.n4.nabble.com/Boost-MSM-No-transition-from-submachine-… Sent from the Boost - Users mailing list archive at Nabble.com.

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Simple example program builds but hangs when I run it. (Ubuntu).
by vincegata 24 Jan '12

24 Jan '12

Hello, I run Ubuntu 11.04. I downloaded Boost 1.48.0, then I followed the instructions from Getting Started on Unix variants to build the libraries into /usr/local/include and /usr/local/lib. Now, I build the Simple example program without any errors, however when I run the program it just hangs indefinitely on std::for_each() line. Could someone help me with this please? $: g++ -g -lboost_filesystem main.cpp #include <boost/lambda/lambda.hpp> #include <iostream> #include <iterator> #include <algorithm> int main() { using namespace boost::lambda; typedef std::istream_iterator<int> in; std::for_each(in(std::cin), in(), std::cout << (_1 * 3) << " " ); int stop = 1; }

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Re: [Boost-users] Need help with Errors in boost MPL, tutorials
by Linh Ha 24 Jan '12

24 Jan '12

> Just on a first glance, looks like you're mistaking ::_1 (placeholder from > Boost.Bind) for boost::mpl::_1 (placeholder from Boost.MPL). They're > incompatible; try using the latter...? > > - Jeff Thanks, Jeff ! It works. But then my next question is why they are different and somehow incompatible even-though are both placeholders. Why we keep two different place holder if they do exactly a same functionality.

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license
by Kraus Philipp 24 Jan '12

24 Jan '12

Hello, I would like to create a PHP plugin that uses the Boost UBlas datatypes. The plugin will be use the GPLv3 license. Can I use the bcp utility to extract the UBlas structures and can I include them into my plugin without any license problems? The plugin should store all needed parts into its own directory. Thanks Phil

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Need help with Errors in boost MPL tutorials
by Linh Ha 24 Jan '12

24 Jan '12

Dear all, I try to learn Meta-programing but i got stuck with lambda meta-function and place holder. I try to compile very simple program #include <boost/bind.hpp> #include <boost/mpl/lambda.hpp> #include <boost/type_traits.hpp> template <class F, class X> struct twice : F::template apply<typename F::template apply<X>::type > { }; template <class X> struct two_pointers : twice<typename boost::mpl::lambda<boost::add_pointer<_1> >::type, X> {}; int main(int argc, char** argv) { return 0; } It is from the boost tutorial http://www.boost.org/doc/libs/1_48_0/libs/mpl/doc/tutorial/the-lambda-metaf… . But it can not be complied. The error messages are main.cpp:21: error: type/value mismatch at argument 1 in template parameter list for ‘template<class T> struct boost::add_pointer’ main.cpp:21: error: expected a type, got ‘<unnamed>::_1’ main.cpp:21: error: template argument 1 is invalid main.cpp:21: error: template argument 3 is invalid main.cpp:21: error: template argument 1 is invalid main.cpp:22: error: expected ‘::’ before ‘{’ token main.cpp:22: error: expected class-name before ‘{’ token I use g++ (Ubuntu/Linaro 4.4.4-14ubuntu5) 4.4.5 I have no idea what happened. Any inside would be appreciated. It is important I think since lambda is used all over place with MPL. Thanks, Linh Ha

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[Spirit][karma] Generating Pascal string like output
by Olaf Meeuwissen 23 Jan '12

23 Jan '12

Hi all, While I had no trouble getting the parsing part for this to work, I'm stuck on the generator part. Specifically, I'm stuck on getting the size into the output. The goal is a rule that takes a std::vector<byte> and outputs it in such a way that it is preceded by its size (in a custom encoding) and padded by zeroes to align on a four byte boundary. I want to reuse this rule in several other rules and prefer to break it up into smaller pieces. A minimalistic example of what I have come up with so far is attached. What I can't seem figure out how to get at and store the vector's size in pascal_string_size_. There also seem to be problems with refering to the stored size_ in pascal_string_payload_ and pascal_string_padding_ that I don't understand. Note that the signed/unsigned distinction is on purpose. I am aware of the side effects of assigning to size_ and that that is not threadsafe. Any help would be appreciated. Thanks in advance, -- Olaf Meeuwissen, LPIC-2 FLOSS Engineer -- AVASYS CORPORATION FSF Associate Member #1962 Help support software freedom http://www.fsf.org/jf?referrer=1962

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grid_graph vertex properties
by David Doria 23 Jan '12

23 Jan '12

Since there is no VertexProperties template parameter on grid_graph, is it correct that you cannot use interior properties, but must use exterior properties? Thanks, David

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Building boost_1_48_0 with specified version of msvc...
by JIA Pei 23 Jan '12

23 Jan '12

Hi, all: I strictly followed "Getting Started" on Boost documentation, although I'm using a Visual Studio 2008 Command Prompt, it seems it always produce all boost libraries using VC10. Is it possible to produce boost libraries built by VC9? Please help...Thank you very much. Best Regards Pei -- Pei JIA Email: jp4work(a)gmail.com cell: +1 604-362-5816 Welcome to Vision Open http://www.visionopen.com

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Regarding Boost::asio::io-service
by Baba Prasad 23 Jan '12

23 Jan '12

Dear Friends, Please tell what is the purpose of boost::asio::io-service ios .I am New to the boost Libraries and I'm doing one Open Source project in that already used these asio service in a way of passing asio service in object. like "link l(ios, some other arguments) " My big question is at what sart of time this asio::io-service are most useful and required. Best Regards BaBu -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.

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Compile error when using program_options and lambda expression
by Jens Auer 23 Jan '12

23 Jan '12

Hi, I ran into a problem when I was replacing boost::bind expressions with lambda expressions. I could boil down the problem to the following code: #include <boost/program_options.hpp> template<typename T> void f(T t) {} void g() { using namespace boost::program_options; // each of the following lines produces the error: // Error 1 error C2871: 'validators' : a namespace with this name does not exist // Error 2 error C2871: 'program_options' : a namespace with this name does not exist f([]() {} ); auto x = []() {}; } When I try to compile this on my Microsoft Visual Studio 2010 using our Boost 1.45 library, I get a compiler errors: Error 1 error C2871: 'validators' : a namespace with this name does not exist Error 2 error C2871: 'program_options' : a namespace with this name does not exist To me, it looks like a compiler problem but I want to make sure that I am not running into a known issue in the boost libraries. I have search the bug database, but I have not found any issues like this one. It would be nice if someone could double-check this on another platform and boost version. If it is a compiler bug, I would then file a bug report to MS. Best regards, Jens

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FTP Server class
by Christer Borgqvist 23 Jan '12

23 Jan '12

Hello all, Im trying to make a multi threaded FTP Server class using boost asio. When in passiv mode, create a server listen on the data port and wait for a connection from the client, that thread need som event to trigg the thread to start send the file after the command RETR have received. is there some one that can help me. /Christer

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[units] Question about user-defined value types
by W Z 23 Jan '12

23 Jan '12

Hi, I am using boost units library for a project in which I need to define quantities using rational numbers. I have a rational number class but am having trouble integrating it with units library. There seems to be a lot of places where the units library implementation assumes that the conversion values are expressed as double type. Is there a good way to get around this to make units library support rational numbers? Thanks, WZ

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Iterating over vertices in a specific region in a graph
by David Doria 22 Jan '12

22 Jan '12

If I manually create a grid graph in BGL (using adjacency_list, not grid_graph), is there a way to iterate over vertices in a specified rectangular region? Say I make a 100x100 grid graph, how would I iterate over the the center 5x5 vertices? Thanks, David

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Multicast sender
by Carlos Guimarães 22 Jan '12

22 Jan '12

Hi, Is there any portable way (by using boost) to send multicast messages through all network interfaces available on the host? I have managed to do it by setting outbound_interface option on the socket. However, how can I know which if_index are available? Also, it only works for IPv6. If I set a IPv4 address it always use the same interface. Any suggestion? Next is the code I'm using: // DATA HERE... ip::udp::socket sock(io); sock.open(ip::udp::v6()); // Set socket flags sock.set_option(boost::asio::socket_base::reuse_address(true)); if (strcmp(dst_ip, "ff02::1") == 0) { boost::asio::socket_base::broadcast option(true); sock.set_option(option); } sock.bind(ip::udp::endpoint(ip::address_v6::any(), src_port)); for(int i = 1; i <= 5; i++) { try { sock.set_option(ip::multicast::outbound_interface(i)); sock.set_option(ip::multicast::enable_loopback(false)); ip::udp::endpoint ep(ip::address::from_string(dst_ip), dst_port); sock.async_send_to(boost::asio::buffer(sbuff, slen), ep, boost::bind((&send_handler), placeholders::error)); } catch(...) { return; } }

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