February 2009 - Boost-users - lists.preview.boost.org

for_each_until like algorithm
by Peter Barker 11 Feb '09

11 Feb '09

Hi, I just wondered if there was already an algorithm (or way to compose one) in Boost that would allow me to iterate over a container of pointers to objects calling a function on each one and completing when one of them returned a particular value? For example, I have a master/child relationship and the master has a method called shouldCalculate(). Whether this returns true is partly dependent on what the children return for their shouldCalculate() method. So I'd like to say something like this: bool Master::shouldCalculate() { // Look at data at the master level to see if it's stale. If it is, return true. // See if any of the children should calculate bool staleChildren = boost::for_each_until(children_.begin(),children_.end(), boost::bind(&Child::shouldCalculate,_1),until_true_returned); return staleChildren; } Regards, Pete

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Boost:Signals and Bind question
by mararual 11 Feb '09

11 Feb '09

Hi Everyone, I have a question on using Signals with a COM server and a client. Is it possible to have a signal on a COM server and a method ConnectSlot(clientMethod) that can be called from a client? I want to have a COM server that when some update is done, notifies all of the slots(subscribers), so that from the clients I can do: helloService->ConnectSlot(boost::bind(&Callback)); where callback is a method in the client. On the server side I have: STDMETHODIMP CHelloService::ConnectSlot(VARIANT aSubscriber) { connect(aSubscriber); //connect(boost::bind(aSubscriber)); return S_OK; } CHelloService::connection_t CHelloService::connect(signal_t::slot_function_type subscriber) { return m_sig.connect(subscriber); } Don't know how to receive the result of Boost::bind from the client. I read Bind supports COM by adding #define BOOST_MEM_FN_ENABLE_STDCALL before the include of bind.hpp. What would you recommend for this approach? Any examples? Thanks in advance, Marcos -- View this message in context: http://www.nabble.com/Boost%3ASignals-and-Bind-question-tp21800004p21800004… Sent from the Boost - Users mailing list archive at Nabble.com.

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Re: [Boost-users] [multi_index] Problem of scope with the replace in static data structure
by Rodrigo Dias Ferreira 11 Feb '09

11 Feb '09

Hi Joaquim, > > Hi Rodrigo, > > First of all let me advice you to add the name of the library to the > subject line > of your post (in this case, [multi_index]) so that authors can more easily > track messages of their particular interest. Thanks for the advice. :) > > Rodrigo Dias Ferreira escribi?: > > Hi there, > > > > I am having a problem with Boost.MultiIndex (I'm using Boost 1.37). > > > > So the problem is the following: > > I am using a static data structure, an index which I use as my graph > > repository: > > [...] > > For manipulating the graphs, I use a Graph_h (handler), which does a > > copy from the graph from this repository, does the changes in the local > > copy, and then the user has to call commitChanges(); to apply it in the > > repository (which I am using the replace function from the MultiIndex > > to commit it). > > > > The problem it is that inside the commitChanges(); I can retrieve from > > the repository through the find function (from MultiIndex). > > > > But when I the main program, it does not work (remark: I am trying > > right after calling the commitChanges(); It founds the graph, but it > > seems to be the old one, and I cannot retrieve the nodes... > > > > The code is too convoluted for me to detect anything suspicious: the > fact that you check > for the newly replaced element just before commitChanges returns and > just after and > have differing results cannot possibly be related to the fact that > DynamicGraphs::_graphRep > is static, so I'd look somewhere else. Suggestions: > > 1. Can you provide a narrowed down compilable program exhibiting the > problem? I think that will be a little hard to do, let's first try these steps below first, maybe you can figure out what it is, because I'm not understanding what could be, since it seems to work inside the function and outside doesn't, and as it is a static data member... > 2. If the answer to 1 is no, can you post the debug console output of > your program? The output of this part of the code (I will mark the part inside the function commitChanges();: ///////////begin commitChanges();///////////////////////////// DEBUG@commitChanges:before replacing:_git Name: COI:0351-123-4555 Node version was not found! DEBUG@commitChanges:after replacing:_git Name: COI:0351-123-4555 Found it: Name: Node:0351-123-4569 Timestamp: 1234340512 Found it: Name: Node:0351-123-4569 Timestamp: 1234340521 ///////////end commitChanges();///////////////////////////// Commit was successful! Retrieving the graph with commit: Node version was not found! - As you can see, inside before replacing, it did not find the nodes inserted, as expected. - Then after replacing it found the nodes inserted (as expected). - But then after goes out of the function, as you can see, no nodes was found it... they shouldn't be there? I mean because the repository is static, I think it should be no reason for the nodes be there inside the function, and outside no... > 3. You're copying values of the type Graph. How's this type defined? Has > it proper copy semantics? Yes, I think so: class Graph { ... public: // TODO: Really constructors /// Default Constructor Graph() { _rangeBegin = 0; _rangeEnd = 0; } /// Copy constructors Graph(const Graph &g) : _rangeBegin(g._rangeBegin), _rangeEnd(g._rangeEnd), _nodeRep(g._nodeRep), _nodeNameRep(g._nodeNameRep), _nodeTimeStampView(g._nodeTimeStampView), _localPropRep(g._localPropRep), _globalPropRep(g._globalPropRep){} ... } > 4. What happens if you try the after-replace check inside > Graph_h::commitChanges > (that is, the section beginning with cout << "DEBUG@commitChanges:before > replacing:_git Name: ") > *twice* rather than just onec? Still got positive results for both checks? Yes. I've added twice before the replace and after, the result is the same (as expected) and still I don't understand why does not work outside... DEBUG@commitChanges:before replacing:_git Name: COI:0351-123-4555 Node version was not found! DEBUG@commitChanges:before replacing:_git Name: COI:0351-123-4555 Node version was not found! DEBUG@commitChanges:after replacing:_git Name: COI:0351-123-4555 Found it: Name: Node:0351-123-4569 Timestamp: 1234341125 Found it: Name: Node:0351-123-4569 Timestamp: 1234341134 DEBUG@commitChanges:after replacing:_git Name: COI:0351-123-4555 Found it: Name: Node:0351-123-4569 Timestamp: 1234341125 Found it: Name: Node:0351-123-4569 Timestamp: 1234341134 Commit was successful! Retrieving the graph with commit: Node version was not found! thanks a lot for the help, I hope you can figure it out what it is happen... best regards Rodrigo > > I'm sorry I can't be more helpful with the info you provide. Looking fwd > to > having your feedback. > > Joaqu?n M L?pez Mu?oz > Telef?nica, Investigaci?n y Desarrollo > > > > > -- ************************************************* Rodrigo Dias Ferreira Master Student of Computational Engineering Technische Universität Dresden - Germany Mobile Phone:+49 171 3158797 E-mail: rodrigodias(a)gmx.de ************************************************* Psssst! Schon vom neuen GMX MultiMessenger gehört? Der kann`s mit allen: http://www.gmx.net/de/go/multimessenger01

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Generating Numbers With Certain Distribution with Boost
by Gundala Viswanath 11 Feb '09

11 Feb '09

Dear all, Is there a way to generate K numbers of integer (K = 10^6). The maximum value of the integer is 200,000 and minimum is 1. And the occurrences of this integer follows a lognormal distribution. - Gundala Viswanath

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Constructing an error code based on the last error?
by Zachary Turner 10 Feb '09

10 Feb '09

Does boost provide a portable way to create a system::error_code object based on the last error? I don't see an obvious way to do this via the documentation unless I'm just overlooking it. There's lots of ways to create uninitialized error code objects, or error code objects initialized to a specific value, but I don't see an obvious portable way of determining "why the last operation failed". Anyone encountered this before?

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[asio] Clients (try to) connect only once
by Jens Weller 10 Feb '09

10 Feb '09

Hi I am writing on a an app, that has clients, which connect, and get events/updates send. Now, it works almost, but still, I got one problem I couldn't solve sofar: My Client only connects or tries to connect once. If the server isn't running, I have to restart the app, to be able to try again. I do get a connection event at the server, but the client seems not to respond to the send data afterwards. I am not sure, if it might be a threading issue, but i think that calling join() should do the job. My Code: void ZMSRClientFrame::OnConnect(wxCommandEvent& event) { // the behavoir happens also with out those 2 ifs (just tried to check that) if(inputhandler) { inputhandler->close(); } if(t) { t->join(); t.reset(); } try{ boost::asio::ip::tcp::resolver resolver(ios); boost::asio::ip::tcp::resolver::query query("127.0.0.1", "3210"); boost::asio::ip::tcp::resolver::iterator iterator = resolver.resolve(query); //InputHandler in(ios,iterator); inputhandler = boost::shared_ptr<InputHandler>(new InputHandler(this,ios,iterator)); //ios.run(); //starting ioservice thread t = boost::shared_ptr<boost::thread>(new boost::thread(boost::bind(&boost::asio::io_service::run, &ios))); } catch(std::exception& e) { wxMessageBox(e.what()); //inputhandler.reset(); } catch(...) {wxMessageBox("could not connect"); //inputhandler.reset(); } } Inputhandler calls async_connect which returns to one of its members. Which works through the first run. How to solve this? regards Jens Weller -- Jetzt 1 Monat kostenlos! GMX FreeDSL - Telefonanschluss + DSL für nur 17,95 Euro/mtl.!* http://dsl.gmx.de/?ac=OM.AD.PD003K11308T4569a

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[boost-users][asio] timeout - is io_service.reset() safe with pool of threads?
by tomasz jankowski 10 Feb '09

10 Feb '09

hello, I'm implementing timeouts according to suggestion placed here http://lists.boost.org/Archives/boost/2007/04/120339.php because I still don't understand fully how io_service work I have question: is this way of implementation of timeout safe when I'm using pool of threads for one io_service? tom ---------------------------------------------------- Kate Winslet i Leonardo DiCaprio znowu razem na ekranie! DROGA DO SZCZĘŚCIA - w kinach od 30 stycznia. Zobacz zwiastun: http://klik.wp.pl/?adr=http%3A%2F%2Fcorto.www.wp.pl%2Fas%2Fszczescie.html&s…

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Re: [Boost-users] [filesystem] windows program crashes in debug mode ( DbgUiConnectToDbg )
by Everton Patitucci 10 Feb '09

10 Feb '09

Stephen Lavelle-2 wrote: > > It appears to run > fine in release mode*, but crashes when debugged. > I don't know if you alredy figured it out, but I was having EXACTLY the same problem using boost::filesystem-1.37-mingw under Windows XP SP2 - Code::Blocks 8.02. After searching a lot I hit a forum post where another guy was having that problem and it resolved to a mix of debug/release libraries being used together. So I solved the problem in the following way: built boost again (as I'm using only filesystem I built filesystem and system libraries only, you can run a "bjam --show-libraries" so you get their name): bjam --with-system --with-filesystem debug and yet again: bjam --with-system --with-filesystem release this will output the libraries in the following path: ./bin.v2/libs/debug|release/link-static|threading-multi linked my project's debug target to the debug library created (i.e. libboost_filesystem-mgw34-mt-d-1_37.lib and libboost_system-mgw34-mt-d-1_37.lib)... same for release target... (libboost_system-mgw34-mt-1_37.lib and libboost_filesystem-mgw34-mt-1_37.lib) I hope it helps you or someone with the same problem. If you or someone else need further explanation, I'll be glad to help. Patuti

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Problem of scope with the replace in static data structure
by Rodrigo Dias Ferreira 10 Feb '09

10 Feb '09

Hi there, I am having a problem with Boost.MultiIndex (I'm using Boost 1.37). So the problem is the following: I am using a static data structure, an index which I use as my graph repository: /// Data member to represent the graph repository (using ordered_unique index) static graphIndex _graphRep; which is from the type graphIndex: ///ordered_unique Index in the data structure graph_hm typedef multi_index_container< graphMap, indexed_by< ordered_unique< BOOST_MULTI_INDEX_MEMBER(graphMap,string,_name) > > > graphIndex; Here is the graphMap: /// GraphMap: Data Structure for setting an index in the uniqueGraphName and retrieving handler Graph_h struct graphMap { string _name; Graph _graph; /// Default Constructor graphMap(){} /// Constructor with parameters: initialize the name and graph graphMap(string uniqueGraphName, Graph graph) : _name(uniqueGraphName), _graph (graph) {} /// Constructor with parameters: initialize the name and graph graphMap(const graphMap &gm) : _name(gm._name), _graph (gm._graph) {} }; For manipulating the graphs, I use a Graph_h (handler), which does a copy from the graph from this repository, does the changes in the local copy, and then the user has to call commitChanges(); to apply it in the repository (which I am using the replace function from the MultiIndex to commit it). The problem it is that inside the commitChanges(); I can retrieve from the repository through the find function (from MultiIndex). But when I the main program, it does not work (remark: I am trying right after calling the commitChanges(); It founds the graph, but it seems to be the old one, and I cannot retrieve the nodes... Why is that happening? Here it is a stretch of code from the main: //Test of the commit if (graph_h.commitChanges()) cout << "Commit was successful!\n"; else cout << "Commit was unsuccessful!\n"; // Debug //Graph_h graph_h; //NodeIterator nodeIt; //Node_h node_h; graphIt it = DynamicGraphs::_graphRep.find("COI:0351-123-4555"); graph_h = Graph_h(it); //propertystream_h propS; propS = graph_h->lookupLocalProp("name"); p_h = propS.next(); cout << "DEBUG@main:right after the commit:_git " << p_h.value() <<endl; nodeIt = graph_h->nodeIterator("Node:0351-123-4569"); if (!nodeIt) cout << "Node version was not found!"<<endl; else //Works for both: one match and range lookup while (!nodeIt.end()){ node_h = nodeIt.next(); cout << "Found it: " << *node_h; } //Debug And here it is the code from inside the commit, which it works!!! bool Graph_h::commitChanges(){ bool success; propertystream_h ps_h = _localGraph.lookupLocalProp("name"); //Exception handling in the case does not find the name property property_h p_h = ps_h.next(); //TODO: Revise about the setting of the time in the graph... too stable _localGraph.resetTimeRange(); // Debug cout << "DEBUG@commitChanges:before replacing:_git Name: " << p_h.value() <<endl; Graph_h graph_h; NodeIterator nodeIt; Node_h node_h; graphIt it = DynamicGraphs::_graphRep.find("COI:0351-123-4555"); graph_h = Graph_h(it); nodeIt = graph_h->nodeIterator("Node:0351-123-4569"); if (!nodeIt) cout << "Node version was not found!"<<endl; else //Works for both: one match and range lookup while (!nodeIt.end()){ node_h = nodeIt.next(); cout << "Found it: " << *node_h; } //Debug success = DynamicGraphs::_graphRep.replace(_git, graphMap(p_h.value(),_localGraph)); // Debug cout << "DEBUG@commitChanges:after replacing:_git Name: " << p_h.value() <<endl; it = DynamicGraphs::_graphRep.find("COI:0351-123-4555"); graph_h = Graph_h(it); nodeIt = graph_h->nodeIterator("Node:0351-123-4569"); if (!nodeIt) cout << "Node version was not found!"<<endl; else //Works for both: one match and range lookup while (!nodeIt.end()){ node_h = nodeIt.next(); cout << "Found it: " << *node_h; } //Debug return success; } I hope someone can help me.. thanks in advance, Rodrigo -- ************************************************* Rodrigo Dias Ferreira Master Student of Computational Engineering Technische Universität Dresden - Germany Mobile Phone:+49 171 3158797 E-mail: rodrigodias(a)gmx.de ************************************************* Jetzt 1 Monat kostenlos! GMX FreeDSL - Telefonanschluss + DSL für nur 17,95 Euro/mtl.!* http://dsl.gmx.de/?ac=OM.AD.PD003K11308T4569a

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Which singleton to use?
by Leandro T. C. Melo 10 Feb '09

10 Feb '09

Hi all. Apparently, there's a possibility of a singleton library in a future release, right? However, in the meanwhile, if I need a basic singleton that provides thread-safe initialization/destruction, which one would you recommend? I ask this because there's more than one Boost library with its own singleton mechanism. Thanks, Leandro.

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