September 2007 - Boost-users

BGL distance recorder
by Andreas Fabri 13 Sep '07

13 Sep '07

Hello, I am wondering if there is not a documentation bug. The distance_recorder<DistanceMap, EventTag> manual page states: DistanceMap A WritablePropertyMap, where the key type and the value type are the vertex descriptor type of the graph. Shouldn't the value type be something like int. After all it is a distance measured in the number of hops in the graph. Also writing my own DistanceMap I had to also provide the function get in order that it compiles. So the DistanceMap should be Readable as well. andreas

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[Graph] dynamically building a graph
by Krishna Roskin 13 Sep '07

13 Sep '07

Hello everyone, I hope this question isn't to vague. I just looking for some general advice. I'm working on a project where I'm dynamically building a graph on the fly as the graph is traversed. For out_edges(...) (and other functions), I've been using something similar to shared_container_iterator to dynamically build the list of out edges. My target and source functions return-by-value objects that represent the vertices. I've also overloaded the operator[] on the graph to return-by-value objects with the edge and vertex properties. I use by-value semantics because the entire graph is never created in memory. But my iterators and graph object don't quite fit into the rest of the boost graph library. For instance, filtered_graphs of my graph don't like that my iterators don't return references to edge_descriptors. I've fixed that problem by defining typedef typename Graph::edge_descriptor reference; in the iterator, i.e. reference aren't really references but returned-by-value objects. But this seem like treating the symptoms and not the cause. And the operator[] of the filtered_graph wants to return references as well and so I get "returning reference to temporary" errors. I've gotten around this by just getting the vertex/edge properties from the original graph. Has anyone else had these problems? Or know of a better way to build graphs dynamically? Any advice or strategies would be appreciated. Thanks, -krish

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Re: [Boost-users] Serialization compile issue [SOLVED]
by Cory Omand 13 Sep '07

13 Sep '07

On 9/13/07, Cory Omand <coryomand(a)gmail.com> wrote: > On 9/13/07, Cory Omand <coryomand(a)gmail.com> wrote: > > On 9/12/07, Robert Ramey <ramey(a)rrsd.com> wrote: > > > Try the following change. > > > > > > Read the explanation in the "rationale" section. > > > > Hi Robert, > > > > Thanks for your reply. I actually did read the rationale section > > prior to coding this example. However, I would have expected the > > STATIC_ASSERT trap if I was passing the wrong thing to the serializer > > (as I did while trying to serialize pointers in a different example). > > I ended up with the sample code I attached to the previous mail via > > the serialization test 'test_map.cpp', which does not serialize via a > > const ref to the map. I came across a posting on another mailing list that suggested that the archive includes should come *before* the serialization includes. This fixed my compile issue. Is there a note about this anywhere in the documentation that I might have missed? - C.

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Building just one library
by Sebastian Pfützner 13 Sep '07

13 Sep '07

Hello, I want to build a specific variant of a specific library and nothing else. If I run bjam --toolset=msvc --with-filesystem runtime-link=shared link=static threading=multi address-model=64 debug stage there are two identical files in the stage directory, one with and one without the boost version at the end. How can I prevent the creation of the file without the version number? And another question: Is there a list of all possible options to bjam building boost? I mean options like runtime-link or address-model. I didn't find any docs describing these parameters. thanks in advance -- Sebastian Pfützner s.pfuetzner(a)onlinehome.de ICQ-ID: 39965036

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connected component on a directed graph
by gast128 13 Sep '07

13 Sep '07

Dear all, I see that it is already posted a lot of times, but i couldn't find an answer. Baiscally we want the connected component given a vertex given a directed graph. So a -> b -> c -> d e -> f would give {a, b, c, d} given b - for directed graphs there is only the strong component algorithm - for undirected graph there is an algorithm - there seems no adapter to fool the Bgl for interpreting a directed graph as undirected. Can anyone help? I am not a graph (or Bgl) expert, so maybe I am overlooking something. Wkr, me

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Serialization compile issue
by Cory Omand 13 Sep '07

13 Sep '07

Hello, I am trying to serialize std containers via boost::serialization, but I am unable to get even simple code samples to compile. I used the serialization test_map.cpp as a guide to arrive at the very simple code that follows: --- snip --- #include <boost/serialization/map.hpp> #include <boost/serialization/string.hpp> #include <boost/serialization/nvp.hpp> #include <boost/archive/xml_oarchive.hpp> #include <iostream> #include <string> #include <map> int main() { std::map<std::string, std::string> data; data.insert(std::make_pair("a", "b")); data.insert(std::make_pair("b", "c")); data.insert(std::make_pair("c", "d")); boost::archive::xml_oarchive oa(std::cout); oa << boost::serialization::make_nvp("data", data); return 0; } --- snip --- Can anyone spot misuse above, or give me some clue as to why this won't compile? I am using boost 1.33.1, with GCC 4.1.1. If I change 'data' to be a simple string, serialization works, but if I use any std::container type (I've tried vector<string>, list<string>, and map<string,string> so far), I get an error of the following form: /usr/include/boost-1_33_1/boost/archive/detail/oserializer.hpp:131: error: invalid use of undefined type 'T3', where T1 = string T2 = list<T1> T3 = struct boost::serialization::extended_type_info_null<T2> /usr/include/boost-1_33_1/boost/serialization/type_info_implementation.hpp:26: error: declaration of 'T3', where T1 = string T2 = list<T1> T3 = struct boost::serialization::extended_type_info_null<T2> /usr/include/boost-1_33_1/boost/archive/detail/oserializer.hpp:132: error: invalid use of undefined type 'T3', where T1 = string T2 = list<T1> T3 = struct boost::serialization::extended_type_info_null<T2> /usr/include/boost-1_33_1/boost/serialization/type_info_implementation.hpp:26: error: declaration of 'T3', where T1 = string T2 = list<T1> T3 = struct boost::serialization::extended_type_info_null<T2> Any assistance would be greatly appreciated. - C.

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[variant] Accessor class for recursive variant type
by hirsch＠bigfoot.de 13 Sep '07

13 Sep '07

Hi, I have a recursive variant type like that: -------------------------- typedef boost::make_recursive_variant<bool, int, double, std::string, std::vector< boost::recursive_variant_ >, std::map<std::string, boost::recursive_variant_> >::type TVType; typedef std::vector<TVType> TVector; typedef std::map<std::string, TVType> TMap; -------------------------- And I implemented an accessor class to extract elements from the variant in a path-linke manner: -------------------------- TMap map; map["longValue"] = 23; map["stringValue"] = "abcde"; TVector subvec; subvec.push_back(42); map["subVector"] = subvec; TVType tv = map; Access acc(tv); std::string sValue = acc.get<std::string>("stringValue"); // "abcde" long nSubValue = acc.get<long>("subVector/0"); // 42 ---------------------------- It is implemented by using a boost::static_visitor. It works fine for now, but I also want to change values which are inside my variant hierarchy. So I have to return a reference-type from my Access helper rather than a value type, but I can't figure out how to do this. Here's the implementation of the accessor as it is now: ---------------------------- class Access: public boost::static_visitor<TVType> { typedef std::list< std::string > TStrList; public: template<typename T> T get(const std::string& sPath, const TVType& tvt) { m_aSplits.clear(); // split the path-parts, neighboring splitters will be // automatically compressed to one. boost::split( m_aSplits, sPath, std::bind2nd( std::equal_to<char>(), '/'), boost::token_compress_on); // remove empty entries for(TStrList::iterator it = m_aSplits.begin(); it!= m_aSplits.end(); ++it) { if(it->empty()) it = m_aSplits.erase(it); } // in case of an exception, transform the boost::bad_get exception to our CIS::Exception try { return boost::get<T>(boost::apply_visitor(*this, tvt)); } catch(boost::bad_get& ex) { throw CIS::Exception(ex.what(), EX_POS); } } TVType operator()(const TVector& v) { // if the splits-list is empty we have found our element, so the TVector itself was requested if(m_aSplits.empty()) return v; const uint32_t nIdx = boost::lexical_cast<uint32_t>(m_aSplits.front()); if(nIdx >= v.size()) throw Exception(boost::format("Invalid index: '%1%' from '%2%' in access path") % nIdx % v.size(), EX_POS); m_aSplits.pop_front(); return boost::apply_visitor(*this, v[nIdx]); } TVType operator()(const TMap& m); { // if the splits-list is empty we have found our element, so the TMap itself was requested if(m_aSplits.empty()) return m; TMap::const_iterator it = m.find(m_aSplits.front()); if(it == m.end()) throw Exception(boost::format("Invalid key: '%1%' in access path") % m_aSplits.front(), EX_POS); m_aSplits.pop_front(); return boost::apply_visitor(*this, it->second); } template<typename T> TVType operator()(const T& t) { return t; } private: TStrList m_aSplits; ///< splitted parts of the path. }; ------------------------ I tried to remove the consts and return a reference, but the compiler claims it can't convert a TVector& to a TVType&. I also tried with pointers but got the same error. Does anybody have an ide how I can implement this functionality? Thanks, Falco

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Choosing the right GRAPH
by Jacques Papper 13 Sep '07

13 Sep '07

Hi, I've been looking around the BGL for some time now, but I still can't decide which graph I should use. Here are my limitations : - Very large graph ( > 40 million vertices) - About 4 to 8 edge per vertex (Sparse) I want to associate to each edge a property P such that : edge (A,B) returns P edge (B,A) returns -P (Directed) BUT I do not want to duplicate the storage of P. If edge (A,B) exists then (B,A) also exists. (Bidirectional) I also want to be able to access all edges connected to vertex A as quickly as possible (so I guess using in_edges and out_edges in a directed adjacency list will be too slow). I think the compressed_sparse_row_graph might be the way to go by storing all duplicate edges (the only implementation for the moment is directedS), but I need a way to not duplicate the properties associated with each edge. All advice will be greatly appreciated !! Thanks Jacques --------------------------- This email contains information that is private and confidential and is intended only for the addressee. If you are not the intended recipient please delete it and notify us immediately by e-mailing the sender. Note: All email sent to or from this address may be accessed by someone other than the recipient, for system management and security reasons. Aircraft Research Association Ltd. Registered in England, Registration No 503668 Registered Office: Manton Lane, Bedford MK41 7PF England VAT No GB 196351245

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Boost library names
by Mark B. 13 Sep '07

13 Sep '07

Hi, I am trying to use string_algo (specifically split) in my program but I have no idea about which Boost library I have to link to. Library naming in Boost is not very regular. For example, to link to the filesystem classes I have to use -lboost_filesystem, but for linking to uBlas, I have to use -lblas. Thus, the substring "boost" is not necessarily in the library's filename Can somebody help me? Thanks! -- View this message in context: http://www.nabble.com/Boost-library-names-tf4431325.html#a12641735 Sent from the Boost - Users mailing list archive at Nabble.com.

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[bind] for_each, Member function question.
by Hughes, James 13 Sep '07

13 Sep '07

I have a question for boost:binders out there... In the following scenario..(pseudocode) Class Fred { typedef std::map<wstring, shared_ptr<SomeType> > MyMap; MyMap Bert; Save(MyMap::iterator pos) { ... } SaveAll() { for_each(Bert.begin(), Bert.end(), bind(&Fred::Save, this, _1); } }; The code wants to save all the data in the map. The bind, I was hoping, would simply call Save for all items in the map, passing in the iterator as the parameter, but I get a template compile fault on the bind. I've tried all sorts of combinations, checked boost docs, read the chapter in Beyond the C++ standard library, Googled etc, but just cannot figure out what I need to do here. Any help gratefully received. James This message (including any attachments) contains confidential and/or proprietary information intended only for the addressee. Any unauthorized disclosure, copying, distribution or reliance on the contents of this information is strictly prohibited and may constitute a violation of law. If you are not the intended recipient, please notify the sender immediately by responding to this e-mail, and delete the message from your system. If you have any questions about this e-mail please notify the sender immediately.

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