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[shmem] and kernel 2.4 / linuxthreads
by Sascha Lumma 03 Jul '06

03 Jul '06

Hi all, I noticed that kernel 2.6 is a requirement for shmem on linux. Is it possible to get shmem to run - maybe with constraints - together with kernel 2.4 and the older pthread version (linuxthreads)? A start on a kernel 2.4 box produces a segmentation fault in shared_memory.hpp. To reach most users as possible, it would be nice to be compatible or if not possible to get as a minimum a normal termination. Sascha Lumma

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[BGL] python bindings build graph from edge list
by John Reid 03 Jul '06

03 Jul '06

Hi, I was trying to build a graph from an edge list and ran into some problems. The following code throws an exception on write_graphviz(). I think it is because there's no property map called node_id in the graph. import boost.graph as bgl edges = [ ( 'a', 'b' ), ( 'b', 'c' ), ( 'c', 'a' ) ] g = bgl.Graph( edges ) g.write_graphviz( 'bind-copy.dot' ) I get the following: Traceback (most recent call last): File "<stdin>", line 1, in ? KeyError: 'node_id' I couldn't manage to generate the node_id property map automatically. So after you have built the graph with the edge list constructor how do you know which vertex is which? I ended up using the following code to create the graph: def build( edges ): # Create a graph to build g = bgl.Graph() # Construct some property maps node_ids = g.vertex_properties[ 'node_id' ] = g.vertex_property_map( 'string' ) color = g.vertex_properties[ 'color' ] = g.vertex_property_map( 'string' ) centrality = g.vertex_properties[ 'centrality' ] = g.vertex_property_map( 'float' ) weight = g.edge_properties[ 'weight' ] = g.edge_property_map( 'float' ) length = g.edge_properties[ 'len' ] = g.edge_property_map( 'float' ) # create the edges and vertices name_2_vertex = { } for ( name1, name2 ) in edges: if not name_2_vertex.has_key( name1 ): v1 = name_2_vertex[ name1 ] = g.add_vertex() node_ids[ v1 ] = name1 else: v1 = name_2_vertex[ name1 ] if not name_2_vertex.has_key( name2 ): v2 = name_2_vertex[ name2 ] = g.add_vertex() node_ids[ v2 ] = name2 else: v2 = name_2_vertex[ name2 ] e = g.add_edge( v1, v2 ) weight[ e ] = 0.1 length[ e ] = 4 # Color articulation points red for v in bgl.biconnected_components( g ): color[ v ] = 'red' # Assign centrality values to property map bgl.brandes_betweenness_centrality( g, centrality ) return g This code seems to works fine. So I thought I'd post this just to see if I was missing something obvious and/or in the hope someone else might find it useful. Best, John.

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[BGL] All Possible Matchings
by Hossein Haeri 03 Jul '06

03 Jul '06

Dear all, I have a bipartite graph, and want to generate all its possible matchings. Any suggestions? TIA, --Hossein ___________________________________________________________ Yahoo! Messenger - with free PC-PC calling and photo sharing. http://uk.messenger.yahoo.com

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[BGL] Bipartite Graphs
by Hossein Haeri 03 Jul '06

03 Jul '06

Dear all, Any special facility there is in BGL for bipartite graphs? TIA, --Hossein ___________________________________________________________ All New Yahoo! Mail Tired of Vi@gr@! come-ons? Let our SpamGuard protect you. http://uk.docs.yahoo.com/nowyoucan.html

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[BGL]Customising the Adjacency List Storage
by Louis Lavery 03 Jul '06

03 Jul '06

According to the book [BGL p232], in order to customise the EdgeList I need to define a container generator and parallel edge traits class, and over load the push() and erase() functions for the custom container [BGL p234]. My custom container is user::PushBackList<T>... namespace user { template<typename ValueType> struct PushBackList { //... }; struct PushBackListS { }; } ...and I've put the (specialised) container_gen and parallel_edge_traits classes in namespace boost... namespace boost { template<typename ValueType> struct container_gen<user::PushBackListS,ValueType> { typedef user::PushBackList<ValueType> type; }; template<> struct parallel_edge_traits<user::PushBackListS> { typedef allow_parallel_edge_tag type; }; } ...now all I need do is overload the push() and erase() functions. The problem is they are in nested namespace graph_detail and are called with full qualification (i.e. boost::graph_detail::push(...)) from adjacency_list class. That means I need to put my overloads in boost::graph_detail. Is that right? Thanks, Louis.

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[BGL] Budled Properties
by Hossein Haeri 03 Jul '06

03 Jul '06

Dear BGL-ers, I'm so new to BGL, and a little mixed up about the properties. Is the "Six Degrees of Kevin Bacon" example in the documentation of 1.33.0 using Bundled Properties? Or, is it using that old style "using_adjacency_list.html" strongly recommended me to leave it? TIA, --Hossein ___________________________________________________________ All New Yahoo! Mail Tired of Vi@gr@! come-ons? Let our SpamGuard protect you. http://uk.docs.yahoo.com/nowyoucan.html

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Re: [Boost-users] Retrieve multindex value type?
by JOAQUIN LOPEZ MU?Z 03 Jul '06

03 Jul '06

----- Mensaje original ----- De: Francesco Biscani <bluescarni(a)gmail.com> Fecha: Domingo, Julio 2, 2006 6:19 pm Asunto: [Boost-users] Retrieve multindex value type? > Hello, > > is there a way to retrieve from a multiIndex container the type of > its content? > > I need to do something like this: > > template <class T> > class my_class > { > private: > T set; > > public: > void insert(const T::value_type &); <------ ? > }; > > Here T is a multiIndex container, and the insert function should > add a term to the set. Hence "insert" must accept as input the > kind of values that are stored in the multiIndex container. Is > there a way to do so or should I just add another parameter to > the template and use that as argument for insert? > Thanks, Hello Francesco, Indeed, multi_index_container provides a nested value_type typedef that you can use exactly in the way you describe. Have you encountered any problem in doing so? Thank you for using Boost.MultiIndex, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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boost 64bit support on windows x64 on amd64 hardware
by Chu-Ming Ng 03 Jul '06

03 Jul '06

Hi, I am porting some code that uses boost from 32-bit to the 64-bit platform and would like to know if the boost library supports this platforms. thanks! Chu-Ming

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Retrieve multindex value type?
by Francesco Biscani 02 Jul '06

02 Jul '06

Hello, is there a way to retrieve from a multiIndex container the type of its content? I need to do something like this: template <class T> class my_class { private: T set; public: void insert(const T::value_type &); <------ ? }; Here T is a multiIndex container, and the insert function should add a term to the set. Hence "insert" must accept as input the kind of values that are stored in the multiIndex container. Is there a way to do so or should I just add another parameter to the template and use that as argument for insert? Thanks, Francesco

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Locking smart pointer
by Mattias Brändström 02 Jul '06

02 Jul '06

Hello! I have a small class to show you and perhaps get some comments on: <code> #include <boost/shared_ptr.hpp> #include <boost/thread.hpp> template <typename T> class LockPointer { public: class LockProxy { public: LockProxy(boost::shared_ptr<T> p, boost::shared_ptr<boost::recursive_mutex> mutex) : p_(p), lock_(new boost::recursive_mutex::scoped_lock(*mutex)) { } boost::shared_ptr<T> operator->() { return p_; } private: boost::shared_ptr<T> p_; boost::shared_ptr<boost::recursive_mutex::scoped_lock> lock_; }; LockPointer(boost::shared_ptr<T> o) : p_(o), mutex_(new boost::recursive_mutex()) { } LockProxy operator->() { return LockProxy(p_, mutex_); } private: boost::shared_ptr<T> p_; boost::shared_ptr<boost::recursive_mutex> mutex_; }; </code> The purpose of this class is to lock a mutex before each method call on an object of class T, and unlock the mutex when that call returns. It seems that this would be something that one would like to have in some cases. Maybe so many cases that it might be part of boost somewhere? I haven't found any library in boost that does this. Is there one? I haven't done anything like this before so it would be nice if anyone here could make some comments on the code. Will it do what I think it does or will it blow up in my face? :-) Regards, Mattias

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