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Accessing Internal Properties
by Jeffrey Holle 02 Aug '04

02 Aug '04

I'm using BGL checked out of CVS on Tue Jun 29 05:25:17 EDT 2004. Also using gcc 3.4.1 on a linux machine. I've a question of how to access internal properties. It appears that there are basically two templated function families for this: get - returns a value get_property_iter_range - returns iterator range get_property - returns a reference Are there more? I'm interested in the later. I've seen in the examples get_property being used to access properties global to a graph, but not edge or vertex properties. What I'd like to see is a varient of get_property (or equivalent) that takes an edge descriptor, so it provides access to a particular edge's named property. Does what I'm looking for exist?

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using boost::shared_ptr with boost::signal
by oliver.kowalke＠t-online.de 01 Aug '04

01 Aug '04

Hi, I want to use boost::shared_ptr with boost::signal. class A { private: int _i; public: A() : _i( 0) {} void operator()( int, std::string & s) { i+= 1; } void operator()( std::string & s, int) { i+= 2; } }; boost::shared_ptr< A > a( new A() ); boost::signal< void( int, std::string &) > rsig; boost::singal< void( std::string &, int) > lsig; rsig.connect( a); lsig.connect( a); rsig(0,"called from right side"); lsig("called from left side",0); Because a is a smart_ptr this code would not compile because operator() is not a member function. If I dereference the smart pointer when I connect to signal, changes of a are never know by the other signal instance. Maybe I can use a proxy class which aggregates the smart pointer but maybe there is a better solution?! with best regards, Oliver -- "Der Spezialist ist ein Barbar, dessen Unwissenheit nicht allumfassend ist." Master's Voice, S.LEM

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boost.graph external properties question.
by Jeffrey Holle 01 Aug '04

01 Aug '04

HI, I'm starting a project that uses boost.graph and I'm trying to decide if I should use internal or external properties. My code that implements external properties is like, for example: typedef boost::graph_traits <GraphT>::vertex_descriptor Vertex; typedef std::map<Vertex,Vertex_Datum,ltDescriptor<Vertex> > VertexData; My question is: Given my use of Vertex as a key of a std::map, it needs to be unique. Is this uniqueness quality maintained across different graphs? That is, can I instanciate 2 GraphT objects and populate both, but maintain only one VertexData container? Assume that I am not defining any internal properties in GraphT.

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Vertex properties in BGL
by Ralph Wessel 01 Aug '04

01 Aug '04

I would like to use the BGL for a project I'm working on, but I haven't been able to find a particular piece of information. The system I'm modeling can be easily represented by a directed graph, but it seems that an essential vertex property can only be calculated on the fly based on the current in-edge and out-edge as the graph is traversed. Can this be supported in the BGL in a way which can feed this vertex property to the supplied algorithms?

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[HELP]How can I print a name of a node in a graph?
by Daniele Carlucci 01 Aug '04

01 Aug '04

Hi everybody, I wanna to print a graph but instead the id I want to print the name of the same. How can I make? I have token the list of the nodes from a list i. In i.name I have the name of the node. The code that I used to initialize the graph is: template <class Graph> void print(Graph& g) { typename Graph::vertex_iterator i, end; typename Graph::out_edge_iterator ei, edge_end; for(boost::tie(i,end) = vertices(g); i != end; ++i) { if (*i!=0){ cout<< *i << " --> "; for (boost::tie(ei,edge_end) = out_edges(*i, g); ei != edge_end; ++ei) cout << target(*ei, g) << " "; cout << endl;} } } void Main() { int nodo, cont, a; nodo=1; typedef graph_traits < file_dep_graph >::vertices_size_type size_type; size_type n_vertices; //Setta n_vertices con il numero di nodi n_vertices=id; // legge il numero di nodi file_dep_graph g(n_vertices); for (i=list.begin(); i != list.end(); ++i) { size_type k; for (cont=0; cont<(*i).v.size(); cont++) { a=(*i).v[cont]; //Connection between node "cont" and all the other nodes add_edge((*i).PID, a, g); } } print(g); Thanks Daniele

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Re: Way to print a route between two nodes
by Gustavo Sÿffffe1nchez 01 Aug '04

01 Aug '04

I don't know exactly how you are traversing those nodes in the path, - ie how do find the path -, but as far as I know you have to use a visitor with an algorithm such as dijisktra shortest paths, so you define the event point, on_finish_vertex for example where you want the visitor to be called. This algorithm also stores in a vector the minimum weight pahts encountered from an specific origin vertex so you can go over those paths from the last vertex to this origin. Hope to be of help ------------------------------ Message: 10 Date: Thu, 29 Jul 2004 15:33:34 +0200 From: Daniele Carlucci Subject: [Boost-users] Way to print a route between two nodes To: boost-users(a)lists.boost.org Message-ID: <4108FCAE.8040301(a)email.it> Content-Type: text/plain; charset=us-ascii; format=flowed Hi all, there is a way to print a route between two nodes? If I have for ie: 8 nodes. A possible route is 1->3->2->6->8 How can I print it? I have only seen that it's used the way to print for every node, all the nodes near that one. Thanks Daniele ------------------------------ ---------------------------------

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serialization for indexed_set?
by Jedediah Smith 01 Aug '04

01 Aug '04

I'm trying to write generic boost::serialization functions for boost:indexed_set and I'm in a bit over my head. The serialization docs say to use something like the following for generic types: template<class Archive, class T> inline void save( Archive & ar, const std::auto_ptr<T> &t, const unsigned int file_version ){ ar << t.get(); } This is a non-intrusive save function for std::auto_ptr. The tricky thing is that the template parameters for indexed_set are much more complicated and the default index may either be regular (set-like) or sequenced (list-like). How would this be handled?

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boost for visual c++
by Jean-Michel besnard 01 Aug '04

01 Aug '04

Hi, How can I install the lib boost::random to use it within Visual C++ (6) ? Is there a built library to be downloaded somewhere or do I have to build it myself ? JM

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std::map(pair) and boost::bind
by Vytautas Leonavicius 30 Jul '04

30 Jul '04

I am often facing the same thing again and again. Say I have a map: map< int, Foo* > m; and I would like to invoke method of Foo on all instances std::for_each(m.begin(), m.end(), boost::bind(&Foo::method, _1 ); The problem is that map contains pair of key and value, not Foo*. Usually I create some function taking pair and invoking method needed on .second. But maybe there is another way to do that? Thanks! Vytautas

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RE: [Boost-users] Re: Bjam- racking my brain
by Brian Braatz 29 Jul '04

29 Jul '04

> Brian Braatz wrote: > > >> Rene Rivera Wrote: > >>build/v2 is not used for building Boost. It's the experimental, and > > > > I am sorry - I am confused and am trying to find my way out: > > > > *- What is listed for download on sourceforge does not reference a > > version of build v1 or bjam v1 or what have you. ( I am confused as to > > how to get the older version) > > OK, some explanation... In SF there are 2 downloads: boost-build-2.0-* > and boost-jam-3.1.*. That boost-build-2.0 is the version 2 I mentioned > which is the experimental version. boost-jam-3.1.* is the scripting > engine BJam (based on Perforce Jam & FreeType Jam) that both V1 and V2 > run on top of. > (snip) Just wanted to thank you Rene for helping me get my head straight on this. I am compiling now with Boost.Build. I have run into another issue that I will be posting on the bjam list (thank you for pointing me to that), but life is definitely nicer. Boost is awesome all by itself, but without the support of the community for those of us getting our heads around these things, boost would not be able to grab more users.

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