- Boost-users - lists.boost.org

Signal/Slot copy semantics.
by Jesper Bojesen 23 Apr '03

23 Apr '03

I have a problem with the sematics of the the signal connect method. Consider this simple program: #include <iostream> #include <boost/signal.hpp> struct HelloWorld { void operator()() const { std::cout << "Hello, World!, the parallel world exist at " << (void *) this << std::endl; } }; int main () { // Connect a HelloWorld slot HelloWorld hello; std::cout << "Main world at " << (void *) &hello << std::endl; boost::signal<void ()> sig; sig.connect(hello); sig (); std::cout << "Thats all folks!\n"; return 0; } It produces this output: >Main world at 0xbffff2e0 >Hello, World!, the parallel world exist at 0x8056128 >Thats all folks! My problem is that the object signalled is not the same object that I subscribed to the signal. Is this really what was inteded ? Is the any rationale behind this behaviour ? -- Jesper Bojesen Medical Insight Email: jbb(a)medical-insight.com Phone mobile: (+45) 40 99 55 03 Phone direct: (+45) 46 55 04 42 Fax: (+45) 46 55 11 66

3 5

UBLAS and algorithms
by David Johnson 23 Apr '03

23 Apr '03

Hi, I'm looking to solve some matrix problems using conjugate gradient methods. CGS and GMRES to name a couple. I see where the matricies can be stored by the UBLAS classes, but I don't see any of the algorithms available in boost. Are they available somewhere? I've looked at packages like IML++ and see them there, but they appear to use different storage classes. Can anyone point me in the direction of where some boost compatible algorithms are? Thanks, Dave

1 0

RE: pool_allocator problems on VC7.1 (real release)
by scleary＠jerviswebb.com 23 Apr '03

23 Apr '03

> -----Original Message----- > From: John Harris [mailto:john.harris@tradingtechnologies.com] > I also tried this on the real released VC7.1 (which has been on MSDN > subscriber downloads for a couple of weeks, now), and, while it > compiles, I get warnings that point me to some code that looks like > it's losing precision (size_type reduced to bool) in a calculation. > The pool code about which the following warnings complain: > > const size_type num_chunks = total_req_size / partition_size + > static_cast<bool>(total_req_size % partition_size); > The cast is intentional. The intent is to add one if the result of the modulus is non-zero. I don't know why the compiler is producing warnings, since I'm using an explicit cast. > Another test I tried was a map<string,string>, actually declared like > this: I'm having a hard time deciphering the compiler errors (I'm not used to MSVC errors), but it looks like it might be a problem in the STL. Have you tried this with STLPort? > If you have an example of a map<string,string> using pool_allocator > that compiles on VC7.1, I'd *love* to see it. That's all I'm really > after, here. Is MSVC available for download for non-MSDN subscribers? If so, I can download it and try to get it working. -Steve

2 1

Trouble grokking iterator adaptors
by Kris Braun 23 Apr '03

23 Apr '03

Hi there, I could really use the features provided by iterator adaptors part of the library, but I'm having a lot of trouble getting a nested set of adaptors to compile. In one case, I'd like to return an iterator into std::map< std::string, boost::shared_ptr< ApiOption > >, and have it return references to options in which option->isTemplate( ) is false. Conceptually, I'd like a filter_iterator->indirect_iterator- >projection_iterator chain. I've been using this typedef to project onto the second member of the pair: typedef boost::projection_iterator_pair_generator< select_second< std::string, boost::shared_ptr< ApiOption > >, OptionMap::iterator, OptionMap::const_iterator > OptionMapIterators; but I've been at a loss to add indirect_iterator and filter_iterator into the mix. Can anyone help me get unstuck? Thank you in advance, Kris

5 7

RE: [Boost-Users] simplest pool_alloc example does not work on VC 6
by scleary＠jerviswebb.com 23 Apr '03

23 Apr '03

John - Sorry, Boost.Pool does not currently support MSVC, due to that compiler's extreme lack of template support. -Steve > -----Original Message----- > From: John Harris [mailto:john.harris@tradingtechnologies.com] > > Using Boost 1.30.0. MSVC6 > Tow problems: (1) I have to #define __WIN32__, and (2) Doesn't compile

3 2

The unholy triumvirate of Boost, MacOS X & gcc
by Paul-Michael Agapow 23 Apr '03

23 Apr '03

Does any one have recent experience with compiling / installing Boost on a Mac using gcc? A brief vox-poll seems to say that most everyone on the Mac uses it with CodeWarrior, manually including it in their project. However I'm more interested in using gcc / ProjectBuilder, and distributing the source code to my programs. So, I need to know if my end-users are going to have any problems installing Boost? My attempts have been been discouraging. The first install of Spirit almost immediately consumed all the memory on my machine and thrashed. Installation of the full Boost failed with link errors reporting "unrecognised option shared". Editing this option out of the regex makefile, lead to the next problem, failures with the unittests. Suspecting I was missing something obvious, I handed the problem over to someone else who spend a few days following the same trail, eventually commenting out the unittests. Sure, I could include the boost source with every program I use it in, but this strikes me as untidy and means every time Boost updates, I have to update the x separate copies on my disk. Opinions or sympathies? p -- Dr Paul-Michael Agapow (p.agapow(a)ucl.ac.uk) Dept. Biology, University College London

3 2

Using for_each on a std::list<boost::function0<void> >
by Russell Hind 23 Apr '03

23 Apr '03

I have a std::list of boost::function0<void> I would like to call all items using a for_each statement. Is there a standard function object that I can pass into the for_each call that will call operator() on each element? Thanks Russell

2 2

dijkstra_shortest_paths with undirectedS example
by jfw1000 23 Apr '03

23 Apr '03

Hello, I am new to BGL, I was trying to test dijkstra_shortest_paths() with undirectedS, the result is not what I wanted, anyone giving help? Thanks, source code like dijkstra-example.cpp in the graph/example. int main(int, char *[]) { typedef adjacency_list < listS, vecS, undirectedS, no_property, property < edge_weight_t, double > > graph_t; typedef graph_traits < graph_t >::vertex_descriptor vertex_descriptor; typedef graph_traits < graph_t >::edge_descriptor edge_descriptor; typedef std::pair<int, int> Edge; const int num_nodes = 3; Edge edge_array[] = { Edge(0, 1),Edge(1, 2), Edge(2, 0) }; double weights[] = {2.0, 1.0, 1.0}; int num_arcs = sizeof(edge_array) / sizeof(Edge);// #if defined(BOOST_MSVC) && BOOST_MSVC <= 1300 graph_t g(num_nodes); property_map<graph_t, edge_weight_t>::type weightmap = get (edge_weight, g); for (std::size_t j = 0; j < num_arcs; ++j) { edge_descriptor e; bool inserted; tie(e, inserted) = add_edge(edge_array[j].first, edge_array [j].second, g); weightmap[e] = weights[j]; } #else graph_t g(edge_array, edge_array + num_arcs, weights, num_nodes); property_map<graph_t, edge_weight_t>::type weightmap = get (edge_weight, g); #endif std::vector<vertex_descriptor> pred(num_vertices(g)); std::vector<double> d(num_vertices(g)); vertex_descriptor s = vertex(0, g); #if defined(BOOST_MSVC) && BOOST_MSVC <= 1300 // VC++ has trouble with the named parameters mechanism property_map<graph_t, vertex_index_t>::type indexmap = get (vertex_index, g); dijkstra_shortest_paths(g, s, &pred[0], &d[0], weightmap, indexmap, std::less<double>(), closed_plus<double>(), std::numeric_limits<double>::max(), 0, default_dijkstra_visitor()); #else dijkstra_shortest_paths(g, s, predecessor_map(&p[0]).distance_map(&d [0])); #endif std::cout << "distances and parents:" << std::endl; graph_traits < graph_t >::vertex_iterator vi, vend; for (tie(vi, vend) = vertices(g); vi != vend; ++vi) { std::cout << "distance(" << *vi << ") = " << d[*vi] << ", "; std::cout << "parent(" << *vi << ") = " << pred[*vi] << std::endl; } std::cout << "min paths tree" << std::endl; adjacency_list<> tree(num_nodes); for(tie(vi,vend) = vertices(g); vi != vend; ++vi) if (*vi != pred[*vi]) add_edge(pred[*vi], *vi, tree); print_graph(tree); std::cout << std::endl; return EXIT_SUCCESS; } The result is : distances and parents: distance(0) = 0, parent(0) = 0 distance(1) = 2, parent(1) = 0 distance(0) = 1, parent(2) = 0 min paths tree 0 -> 1 2 1 -> 2 -> I think the correct one should be: distances and parents: distance(0) = 0, parent(0) = 0 distance(1) = 2, parent(1) = 2 distance(2) = 1, parent(2) = 0 min paths tree 0 -> 1 1 -> 2 2 -> Any idea what is wrong? thanks!

3 3

RE: [Boost-Users] simplest pool_alloc example does not work on VC 6
by scleary＠jerviswebb.com 23 Apr '03

23 Apr '03

> -----Original Message----- > From: Ben Hutchings [mailto:ben.hutchings@businesswebsoftware.com] > > scleary(a)jerviswebb.com wrote: > > Sorry, Boost.Pool does not currently support MSVC, due to that > compiler's > > extreme lack of template support. > <snip> > > For VC++ 6, all that should be needed is a _Charalloc function (instead > of struct rebind) and a change to the type of deallocate's first > parameter (to void *, which actually makes more sense). The _Charalloc function requires each allocator to be able to allocate an arbitrary amount of memory. This goes against the entire design of Boost.Pool, and would be non-trivial (to say the least) to implement. > The VC++ 7 compiler is good enough to support standard allocators and > the library does use them. With the addition of a variable name and > semi-colon, the given example can be compiled with this version. Glad to hear it. Too bad it's not released yet. -Steve

2 1

RE: [Boost-Users] Boost::Filesystem: Directory iterator and dangling links
by Ben Hutchings 23 Apr '03

23 Apr '03

You wrote: <snip> > In the case of dangling links I obtain a not_found_error. > This seems to be a contradiction. First I find something (and obtain an > iterator) and without any interference from > outside is_directory() tells me it cannot find the object. > The problem is that directory_iterator refers to the link whereas > is_directory() and the following exception refer to the target (which is > missing). <snip> To make this consistent, then, maybe is_directory() and friends should be using lstat rather than stat on Unix. Is it desirable that links be resolved? I suppose it is if the iterator is being used to walk a whole tree - but not if it's being used to list a single directory. Perhaps there is a need to include explicit support for links in the API. Windows has supported them since 2000, so they aren't just a Unix thing now.

2 1