January 2013 - Boost-users - lists.preview.boost.org

HTTP server3 example question
by huvcbo 25 Jan '13

25 Jan '13

Hi all, I have problem with HTTP Server3 example, in connection::handle_write i have a dedline_timer with a async_wait. but before the handle_timed execute the connection_ptr goes out of scope, why? Appriciate any help. Christer The boost HTTP Server 3 in file connection.cpp in server.hpp boost::shared_ptr<connection> connection_ptr; server.cpp void server::handle_accept(const boost::system::error_code& e) { if (!e) { new_connection_->start(); new_connection_.reset(new connection(io_service_)); acceptor_.async_accept(new_connection_->socket(), boost::bind(&server::handle_accept, this, boost::asio::placeholders::error)); } } in connection.cpp void connection::handle_write(const boost::system::error_code& e) { if (!e) { const boost::shared_ptr<boost::asio::deadline_timer> t(new boost::asio::deadline_timer(*io_service_, boost::posix_time::seconds(15))); } } void connection::handle_timed( const boost::system::error_code& ec, const boost::shared_ptr<boost::asio::deadline_timer> t) { syslog(LOG_INFO, "handle_timed: %s", ec.message().c_str()); }

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boost::bind/boost::function and fast delegates
by Littlefield, Tyler 24 Jan '13

24 Jan '13

hello all: We have a project we're working on that will be distributed, and I didn't want to have to set boost as a dependency if we're only using boost::bind and boost::function. Given this, I had a couple steps. First I thought I could possibly just copy out the code and modify it a bit, but it uses a ton of boost::preprocessor, so that'd require copying that out too. I'd rather not imbed half of boost in the project. My other solution (and one I really like) was to write my own delegates. I set to work on this and it's coming out good, but I have a couple questions. I know you can assign function pointers to boost::function objects, though I've always done it through bind. I'm curious how this works though: I have a normal function pointer set up and working right now, but how does boost::function take other pointers (say to static methods)? Also I'm curious what boost::bind generates. I'd like to create my own version since I love using it to pass in arbitrary values/using placeholders, but the boost::function has to be able to take a newly constructed function object and bind to that from what I understand. The new function object somehow has it's arguments stored on the object so that the () operator can just pass those in. Any help here would be appreciated. Thanks, -- Take care, Ty http://tds-solutions.net The aspen project: a barebones light-weight mud engine: http://code.google.com/p/aspenmud He that will not reason is a bigot; he that cannot reason is a fool; he that dares not reason is a slave.

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Re: [Boost-users] intrusive_ptr vs shared-ptr
by John M. Dlugosz 24 Jan '13

24 Jan '13

Gottlob Frege<gottlobfrege(a)gmail.com> wrote: > Yes, I was wondering if the magic call inside of smart_ptr's constructor, > that handles the enabled_shared_from_this, wouldn't be better as a free > function, like smart_pointer_being_created(), which gives you an extension > point to go look up whether the object already had a smart pointer. It > could default back to the enabled_shared_from_this trick if you don't > override it for your types, etc. > > Qt's smart pointer has extra tracking like this - typically only turned on > in debugging. The issue boils down to non-intrusiveness. I used a base class 'can_handle' for types I planned on using smart pointers on, much as you inherit from enable_shared_from_this but without the need for CRTP. The free function that looks up the 'lifetime object' for any given pointer (which may or may not already exist in the system) can be overloaded for different ways of doing it for different classes, and inheriting from that base allows it to match the intrusive form. Now as it turns out I never needed to make shared_ptr's to types that I did not define (or trivially derive from), so it never bothered me; but the intent was that a non-intrusive general solution would use a map or something. Only later did I figure out the catch: knowing when the map can be cleaned up of counts to deleted objects. Certainly it can be done: the logic in the smart pointer "I hit zero, free it" code can call another free function to report it; the deleter can capture the need to supplement the normal destructor with additional cleanup; etc. Certainly with the maturity of current compilers there is no reason not to support "lost and found" in an efficient manner. If non-intrusive, it only pays for it when you construct a smart pointer from a raw pointer (potential "find"), and for creating fresh objects a make_shared bypasses that step and knows that it does not exist already in the system anyway. Or, just as you have shared_from_this available now only if enabled, you can have lost-and-found available only if enabled using the intrusive mechanism. Basically, shared_from_this would always work whether it was "in the system" already or not, and constructing a shared_ptr from a raw ptr that has such a base class would call shared_from_this on it rather than new'ing up the counter object. Easy. Hmm, a non-standard shared_from_this mechanism that works this way could still interoperate with code that expects standard shared_ptr class to be used, if you call it that way yourself when you need to "find". Standard code never will, and constructing a shared_ptr the normal way still works as it always did. Now I have noticed that the implementations for shared_from_this interact with internals of weak_ptr. But a portable implementation doesn't have to. If I had time to write for magazines (and such magazines still existed) I'd write that up for an issue. —John

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(no subject)
by khaled hamidouche 24 Jan '13

24 Jan '13

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[1.53.0] Beta1 release available
by Marshall Clow 24 Jan '13

24 Jan '13

Boost release 1.53.0 beta 1 is now available from SourceForge. See https://sourceforge.net/projects/boost/files/boost/1.53.0.beta.1/ This release contains numerous enhancements and bug fixes for existing libraries. For details of what's in the release, see http://www.boost.org/users/history/version_1_53_0.html. Please download the beta, give it a try, and report any problems you encounter. Thank you, -- The Boost Release Team Beman Dawes, Eric Niebler, Rene Rivera, Daniel James, Vladimir Prus and Marshall Clow.

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[MultiIndex] question on replace() documentation
by John M. Dlugosz 24 Jan '13

24 Jan '13

“|replace| performs this substitution in such a manner that: … Iterator and reference validity are preserved.” I suppose "Iterator validity is preserved" means that no iterators are invalidated by this operation. Does that refer to the iterator passed as the first argument, too? That is, the iterator that referred to the replaced element now refers to the new element? And other indexes' iterators referring to the same element (e.g. project()) too? That might still be "valid" in the STL sense but might not continue to work if the position changed (e.g. it is now past the end of the range you are following). That's presuming the changed (but still "valid") iterator follows the new sort order rather than remembering the original order. Can someone clarify? My original reason for writing was to as what is meant by "reference validity is preserved"? Does that mean that the address of the items stored in the collection are not changed, and never move around as a result of this operation? —John

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Re: [Boost-users] [Graph] betweenness_centrality - output completed percentage?
by The Maschine 24 Jan '13

24 Jan '13

Hi Nick, Thanks a lot for both comments! We currently use an "approximation/sub sampling" algorithm done 10years ago by a colleague but its take 10 times more than BGLs and Im not sure its statistically verified. The paper seems really good. About the brandes_betweenness_centrality_impl(), I suppose you are implying that I have to change the boost.graph header file directly? Right? Best, Tasos > > Message: 5 > Date: Wed, 23 Jan 2013 20:54:16 -0500 > From: Nick Edmonds <ngedmond(a)cs.indiana.edu> > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] [Graph] betweenness_centrality - output > completed percentage? > Message-ID: <F264944D-B0A4-4FB6-BDF0-635E9DCCC199(a)cs.indiana.edu> > Content-Type: text/plain; charset="us-ascii" > > Hi Tasos, > > The outer loop of betweenness centrality is a loop over all the vertices > in the graph with each used as the source of a shortest paths computation. > If you want to see how far along the algorithm is you can just instrument > the "for (boost::tie(s, s_end) = vertices(g); s != s_end; ++s)" in > brandes_betweenness_centrality_impl(). Note that you don't actually need > to count shortest paths from *every* vertex in the graph to get a good > approximation of betweenness centrality, check out this paper [1]. > Sampling the vertices in the graph and counting shortest paths from a > subset of them should significantly speed up betweenness centrality if a > (relatively good) approximation will work for your application. > > Cheers, > Nick > > [1] http://www.cc.gatech.edu/~bader/papers/ApproxBC.html > > On Jan 22, 2013, at 8:04 AM, Tasos wrote: > > > Hello all, > > > > I calculate the betweenness-centrality of a large graph > > (V:150k, E:500k, boost::adjacency_list<boost::vecS, boost::vecS, > > boost::undirectedS,) with boost::brandes_betweenness_centrality > > and I can find how to get a indication of the 'completed' > > part of the algorithm. > > > > For example this graph took 1h:38m (single thread 10.8 iMac 3.4ghz) > > to complete but in order to be able to know the execution time > > of larger graph im a bit lost... > > > > On "one to all" BFS you know how many vertices you > > have left but this algorithm seems to me lacking a custom > > visitor or something in order to output some data. > > > > Any ideas as Im really new to boost.graph? > > > > Thanks a lot, > > Tasos > > > > _______________________________________________ > > Boost-users mailing list > > Boost-users(a)lists.boost.org > > http://lists.boost.org/mailman/listinfo.cgi/boost-users > >

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Re: [Boost-users] Range library suggestion
by John M. Dlugosz 24 Jan '13

24 Jan '13

On 1/24/2013 3:59 AM, boost-users-request-at-lists.boost.org |Boost/Allow to home| wrote: > >> >I just added my second metafunction of the form is_range_of_X<T> for use >> >with enable_if, and although the first one took some fiddleing to pass >> >both compilers I was using, the second was a clone of the first with the >> >name and type changed. So it really ought to be a general purpose >> >is_range_of<Whatever, T> metafunction. > I assume it it's simply something like > is_same<typename mpl::eval_if< is_range<T>, range_value<T>, void>::type, > Whatever> I ended up with: template <typename Flag, typename T> struct is_range_of_MYTHING2 : boost::mpl::false_ { }; template <typename T> struct is_range_of_MYTHING2<boost::mpl::true_, T> { typedef typename boost::range_value<T>::type val_type; // chokes here if T is not a range typedef typename is_convertible<val_type, MYTHING>::type type; }; template <typename T> struct is_range_of_MYTHING : is_range_of_MYTHING2<typename boost::has_range_iterator<T>::type, T> { }; I'm familiar enough with type_traits, but not with all of Boost MPL. Is eval_if a lazy-evaluation for short circuiting the AND of the two tests? ---John

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boost asio disign
by Christer Borgqvist 24 Jan '13

24 Jan '13

Hello, how can I design an application that will have a http server like HTTP Server 3 example, but also x number of tcp clients connecting to a server, client must connect to the server before the http server is active, if client is idle with a timer events send an 'I'm here' in every 10 seconds, i tink i have to put the tcp client on a list or ?. Data is received by the http server get the client from list, if non available wait for x amount of time, if time elapsed return incomming data, else, parsing on incomming data, send to tcp server, parse response data put the client back on the list, send response on http, when sending data via tcp client reset the timer. I have the http server working but how do I do with the tcp client, design the threads, should there be only one io_service?, I dont now, im lost! Appreciate all the help. /Christer

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[Graph] betweenness_centrality - output completed percentage?
by Tasos 24 Jan '13

24 Jan '13

Hello all, I calculate the betweenness-centrality of a large graph (V:150k, E:500k, boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS,) with boost::brandes_betweenness_centrality and I can find how to get a indication of the 'completed' part of the algorithm. For example this graph took 1h:38m (single thread 10.8 iMac 3.4ghz) to complete but in order to be able to know the execution time of larger graph im a bit lost... On "one to all" BFS you know how many vertices you have left but this algorithm seems to me lacking a custom visitor or something in order to output some data. Any ideas as Im really new to boost.graph? Thanks a lot, Tasos

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Boost.Process and STARTUPINFOEX
by Nelson Teixeira 23 Jan '13

23 Jan '13

Hello, First, if this is not the correct place to ask, please point me an appropriate forum/maillist about Boost.Process as I couldn't find any in their site. Thanks. I'm trying to use Boost.Process library in windows XP. I installed Boost libraries version 1.52, and used Boost.Process from this page: http://www.highscore.de/boost/process0.5/index.html however, when I made the includes in my test program, I get this error: C:\boost/boost/process/windows/executor.hpp:120:5: error: 'STARTUPINFOEX' does not name a type C:\boost/boost/process/windows/executor.hpp: In constructor 'boost::process::windows::executor::executor()': C:\boost/boost/process/windows/executor.hpp:24:24: error: 'EXTENDED_STARTUPINFO_PRESENT' was not declared in this scope C:\boost/boost/process/windows/executor.hpp:30:23: error: 'startup_info_ex' was not declared in this scope C:\boost/boost/process/windows/executor.hpp:34:9: error: 'STARTUPINFOEX' was not declared in this scope I can't find this STARTUPINFOEX. At most I have STARTUPINFO structure. Do I have to install anything else ? Can anyone help please ?/ Thanks -Nelson ------------------------------------------------- Blog: Além do Óbvio http://www.alemdoobvio.com

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intrusive_ptr vs shared-ptr
by ilya shlyakhter 23 Jan '13

23 Jan '13

Dear Boosters, The documentation of intrusive_ptr says "As a general rule, if it isn't obvious whether intrusive_ptr better fits your needs than shared_ptr, try a shared_ptr-based design first." but does not explain why. If the classes involved are all my own and deriving them all from a base class that implements reference-counting is not a problem, what are some reasons to prefer shared_ptr to intrusive_ptr? Thanks, Ilya

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Range library suggestion
by John M. Dlugosz 23 Jan '13

23 Jan '13

I just added my second metafunction of the form is_range_of_X<T> for use with enable_if, and although the first one took some fiddleing to pass both compilers I was using, the second was a clone of the first with the name and type changed. So it really ought to be a general purpose is_range_of<Whatever, T> metafunction. I would suggest that such a thing be added to the Range library. It is meant for overloaded forms that operate on ranges, and you don't want to accept just any ol' thing because, perhaps, you want other overloads or to get better error messages for bad arguments. A typical example would be something like: void insert (const C& x); template <typename R> typename enable_if<typename is_range_of<C,R>::type, void>::type insert (const R& range) { ⋯ } In my case, I check whether R is indeed a Range (something that appears at first to be missing from the library too, but has_range_iterator is probably what is really meant by that) and the underlying element is convertible to the desired type. In a general-purpose library you might need to put more thought into what tests are so common as to be worth reusing at that level. I think having convertable-to-C (where you just give C) and another one which lets you pass in another metafunction for matching the element would allow reuse of experly written common code that takes care of nuances across compilers, e.g. choking on value_type if the outer is NOT a range, so you need to ensure short-circuit evaluation of the meta-expression. —John

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[mpl] Suggestion on handle protocol messages
by Daniele Barzotti 23 Jan '13

23 Jan '13

Dear, I need to handle a protocol defined with Protocol Buffers. My messages are defined as: enum EMessages { E_MSG_METHOD_CONNECT = 0x8001, E_MSG_EVENT_CONNECT = 0xA001, ... } struct MsgHeader { long sessionRef; long transactionId; long status; } struct MSG_METHOD_CONNECT { Messages opCode; MsgHeader header; .. other fields .. } Now, I defined an interface and a template class to add a level of indirection.. class IMessage { virtual INT getOpCode() = 0; virtual STRING getName() = 0; virtual size_t getSize() = 0; .... } template<class MESSAGE> class IMessageImpl : public IMessage { protected: MESSAGE m_Message; ///< The Message Implementation public: virtual MESSAGE& getMessage() = 0; }; Where I'll use IMessageImpl<MSG_METHOD_CONNECT> MsgConnect; Now, the problem in this situation is to build the correct message class on the receiving part, knowing only the Message opCode. I would like to manage the messages with a type list or map, but I'm a newbie in MPL... Is there a way to define something like this: boost::mpl::map<int, MESSAGE> where the key is the Message opCode and the MESSAGE is the message type? The idea was born reading this article: http://blog.florindinu.ro/posts/message-dispatching-in-c-part-1-type-lists.… Thanks in advance, Daniele.

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Boost and OMPL : access graph vertex
by Dan 23 Jan '13

23 Jan '13

Hello, I'm using OMPL (the Open Motion Planning Library) that makes use of Boost. The problem I've got is that I need to access the content of the vertexes of a graph which is returned by an OMPL function. In particular, the OMPL function is const Graph& g = planner->as<ompl::geometric::PRM>()->getRoadmap(); Now, given the graph g, and a vertex v, I need to read the state contained in g[v] and copy it to an OMPL variable. I'd need something like const ompl::base::State* state = FUNCTION_GET_STATE(g,v) ; This way I would be able to extract from variable state the components x,y,z I'm interested in. Is there any way to implement the FUNCTION_GET_STATE ? Thank you! Dan -- View this message in context: http://boost.2283326.n4.nabble.com/Boost-and-OMPL-access-graph-vertex-tp464… Sent from the Boost - Users mailing list archive at Nabble.com.

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Re: [Boost-users] boost::bind/boost::function and fast, delegates
by John M. Dlugosz 23 Jan '13

23 Jan '13

On 1/22/2013 4:34 AM, boost-users-request-at-lists.boost.org |Boost/Allow to home| wrote: > And if you still wish to write such a lib(s) take a look at this article: > > http://www.codeproject.com/Articles/7150/Member-Function-Pointers-and-the-F… Coincedentely, that article references my project that I cited on another thread (shared pointers): > For Microsoft's (and Intel's) ugly, non-standard 12 byte |virtual_inheritance| pointers, > yet another trick is used, based on an idea invented by John Dlugosz. To pass bound member functions to legacy code (including OS API) that expects a genuine function pointer, I generated a thunk at run-time and used a compiler trick to get the information I needed regarding the 'this' adjustment. It is certainly the _fastest_ possible; but I did not elaborate on a full "bind" feature like Boost (and std) eventually came up with. In fact, I simplified my own code so that all the arguments to pass were just members of one structure, so I only worried about the case of binding to a member function with one argument. It didn't automatically capture smart-pointer objects for the binding, but I handled that separately since it was already being done for "windows" owned by the OS's reference to raw pointers; I had my own fake +1 count as part of the object, and Window objects were my primary interest. As I recall, the C++11 lambda spec provides for a primitive C function pointer to be coughed up, but I've not yet used a compiler that can do that.

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Re: [Boost-users] intrusive_ptr vs shared-ptr
by John M. Dlugosz 23 Jan '13

23 Jan '13

> Well I wouldnt say these items are 'marginal', because most come from real life > scenarios. You can work around things but it is always that u have to remember that > there were some boundary cases with shared_ptr. It took me some time to convince my > colleagues to swap from raw pointers to shared pointers and having some boundary cases > doesn't help then. I still prefer shared pointers, but I am not sure if all in all they > would be better than e.g. intrusive_ptr's with ref counting (even without lacking the > weak_ptr feature). Note that i look upon this from a client perspective (i.e. large data > acquisition application), not from a library builder perspective. I really miss having a "lost and found" feature, which (in the late 90's) I wrote about as being one of the six essential features of my smart pointer design. That is, given a raw pointer p that is already known to the smart pointer system, creating another smart pointer from p will work in harmony with them, NOT break it. I've repeatedly come across code that hooks up objects with other objects in the constructor and I've had to work-around that in various ways, usually by adding a Create wrapper that finishes the work, and sometimes fiddling more than I would have wanted to with the design. I've also found cases where it is really annoying not knowing whether another smart pointer has already been created yet for the object. Anyway, for intrusive smart pointers, the "lost and found" feature is very easy and efficient to implement. So perhaps it should be part of Boost intrusive_ptr as an extension to the standard, or another class can be added with a different feature set. Anyway, if you want a class like that, feel free to grab my old code from the "Classics" or "Repertoire" project parked on github. —John

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[Program Options] terminate parsing after first positional argument
by Stuart Pook 22 Jan '13

22 Jan '13

Hello, How can I tell Boost Program Options to stop parsing the arguments as soon as it finds a positional argument? I'd like to be able to parse the argument list "-v chmod -R -v 600 foo" as having one argument for my program (-v) and the rest as a std::vector of std::string (including the -v). In the attached program I have tried 2 different approaches. The first uses multitoken with the arguments "--command date -u -v", it fails because "-u" isn't known. The second uses collect_unrecognized with "chmod -R -v 600", it doesn't work because -v is interpreted by boost and doesn't end up in the vector. As someone said back in 2005, perhaps I'm trying to write xargs: http://thread.gmane.org/gmane.comp.lib.boost.user/9529/focus=9641 I know that I can ask my users to write a.out -v -- chmod -R -v 600 foo but I don't want to do that. I want them to write "a.out -v chmod -R -v 600 foo". The first positional argument should should tell boost to stop processing. Another slightly different question. If I have a multitoken option that takes doubles how can I get it to accept negative values? If I give my program "--floats 1 8 -4 6" where --floats starts a multitoken option that accepts double, I get an exception saying that "-4" is an unknown option. thanks Stuart This is what my test program gives me with boost 1.50: argv: dd --command date -u -v unrecognised option '-u' Allowed options: -v [ --verbose ] verbose --command arg command to run 2nd try argv: dd chmod -R -v 600 I'm verbose v: chmod -R 600 3rd try argv: dd --floats 1 8 -4 6 unrecognised option '-4' Allowed options: -v [ --verbose ] verbose -f [ --floats ] arg numbers and my program (formatted to fit in 80 characters) #include <boost/program_options.hpp> #include <boost/range/algorithm.hpp> #include <boost/program_options/parsers.hpp> #include <boost/program_options/options_description.hpp> #include <iostream> namespace po = boost::program_options; #define nelements(a) (sizeof (a) / sizeof (a)[0]) void print(char const * * b, char const * * e) { std::cout << "argv: "; std::copy(b, e, std::ostream_iterator<char const *>(std::cout, " ")); std::cout << std::endl; } int main(int argc, char ** argv) { { bool verbose; std::vector<std::string> command; po::options_description desc("Allowed options"); desc.add_options() ("verbose,v", po::bool_switch(&verbose)->default_value(false), "verbose") ("command", po::value<std::vector<std::string> >(&command) ->multitoken(), "command to run") ; char const * args[] = { "dd", "--command", "date", "-u", "-v", 0 }; print(args, args + nelements(args) - 1); po::variables_map vm; try { po::store(po::command_line_parser(nelements(args) - 1, args) .options(desc).run(), vm); po::notify(vm); if (verbose) std::cout << "I'm verbose\n"; std::cout << "command: "; boost::copy(command, std::ostream_iterator<std::string>(std::cout, " ")); std::cout << std::endl; } catch (boost::program_options::unknown_option & x) { std::cerr << x.what() << "\n" << desc << "\n"; } } std::cout << "2nd try\n"; { bool verbose; po::options_description desc("Allowed options"); desc.add_options() ("verbose,v", po::bool_switch(&verbose)->default_value(false), "verbose") ; char const * args[] = { "dd", "chmod", "-R", "-v", "600", 0 }; print(args, args + nelements(args) - 1); po::variables_map vm; po::parsed_options parsed = po::command_line_parser(nelements(args) - 1, args). options(desc).allow_unregistered().run(); try { po::store(parsed, vm); } catch (boost::program_options::unknown_option & x) { std::cerr << x.what() << "\n" << desc << "\n"; exit(2); } po::notify(vm); if (verbose) std::cout << "I'm verbose\n"; std::cout << "v: "; std::vector<std::string> v = po::collect_unrecognized( parsed.options, po::include_positional); boost::copy(v, std::ostream_iterator<std::string>(std::cout, " ")); std::cout << std::endl; } std::cout << "3rd try\n"; { bool verbose; std::vector<double> f; po::options_description all("Allowed options"); all.add_options() ("verbose,v", po::bool_switch(&verbose)->default_value(false), "verbose") ("floats,f", po::value<std::vector<double> >(&f)->multitoken(), "numbers") ; char const * args[] = { "dd", "--floats", "1", "8", "-4", "6", 0 }; print(args, args + nelements(args) - 1); po::variables_map vm; try { po::store(po::command_line_parser(nelements(args) - 1, args) .options(all).run(), vm); po::notify(vm); if (verbose) std::cout << "I'm verbose\n"; std::cout << "floats: "; boost::copy(f, std::ostream_iterator<double>(std::cout, " ")); std::cout << std::endl; } catch (boost::program_options::unknown_option & x) { std::cerr << x.what() << "\n" << all << "\n"; } } }

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boost::program_options - undocumented "*" feature
by ST 21 Jan '13

21 Jan '13

I recently discovered an undocumented feature of `boost::program_options`, namely that it accepts "*" as a special wildcard that allows declaration of a group of options with the same prefix, like this: configOptions.add_options() ("item_*", value<int>(), "items"); This declaration worked as expected and recognized `item_1`, `item_3`, etc, while rejecting unknown options. Well now the question is, how can I write a custom validate function that will populate a map with options key and its value, like this: map<string, int> itemsMap; options_description items("items options"); items.add_options() ("item_*",value<map<string, int>>(&itemsMap)->multitoken(), "items") ; My question is - how do I get the key of the option being validated from within validate() function? template <typename T> void validate(boost::any& v, const std::vector<std::string>& values, map<string, T> *, int) Thank you, Simone

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Support for windows NTLM Authentication Protocol
by Gheorghe Marinca 21 Jan '13

21 Jan '13

Hi, I use asio and need to connect to a proxy server that might require NTLM Authentication Protocol. Is there a way to use this using boost ? Thanks, -Ghita

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Re: [Boost-users] [MultiIndex] more on key extractor issues
by John M. Dlugosz 21 Jan '13

21 Jan '13

On 1/20/2013 11:00 AM, boost-users-request-at-lists.boost.org |Boost/Allow to home| wrote: > From: Joaquin M Lopez Munoz<joaquin(a)tid.es> > Thanks for your elucidation. I'm much more comfortable with the class now. Like most people in this situation, having found the explanation I'm much to busy trying to employ it in real-world projects and don't have time to edit and expand the docs. But, a pointer to your responses on an archiver might be a great quick addition to the documentation page. It occures to me that if the docs were a Wiki then more might get done, including fixing typos and putting this kind of commentary on the Discussion page. —John

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[MSM] Get state name as string
by Stefan Wiehler 20 Jan '13

20 Jan '13

Hello, For debugging purposes, I want to get the current state name as a string. For this purpose I found the class get_state_name in the tools section of the backend. Unfortunately there is no example on how to use this method in the documentation nor anywhere else; and the extensive use of templates makes it very difficult for me to infer this. I am especially confused about the argument boost::msm::wrap<StateType> const& of the call operator. What do I have to provide her? Could anybody please post a short example how to this? Kind regards, Stefan Wiehler

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Re: [Boost-users] [MultiIndex] more on key extractor issues
by John M. Dlugosz 20 Jan '13

20 Jan '13

> Have you taken a look at the table in: > > http://www.boost.org/libs/multi_index/doc/tutorial/ > key_extraction.html#advanced_key_extractors > > Regardless of whether the indexed-by member is const or not, when using > pointers to const elements the proper way of declaring the extractors is: > > > member< > ItemBase, > const unsigned long, > &ItemBase::some_member > > > > member< > ItemBase, > const S2, > &ItemBase::another_member > > > > This should clear problems away both in VS and Clang (please report > otherwise.) > > Joaqu?n M L?pez Mu?oz > Telef?nica Digital > > I read that part in detail (including the typo, T:gg instead of T::gg), going over all the MI docs again after my postings. I agree this seems to address that use-case, but I really don't understand the table and section, and certainly had no clue what it was getting at when I read it without this issue specifically in mind. "The column "applicable to |const| elements?" states whether the corresponding key extractor can be used when passed constant elements (this relates to the elements specified in the first column, not the referenced |T| objects)." What does that mean? I was actually looking at this in regards to figuring out what a non-const member function extractor was good for. "this also implies that |multi_index_container|s of elements of |T| cannot be sorted by |T::g| or |T::gg|," if you are not using it to sort by, what is the point of having the key extractor? Anyway, I found that it works correctly on both compilers if the middle argument (the key type) is declared const for member and not for const_mem_fun. I suppose that is due to differences in the metaprogramming, but really they should be treated the same. Const on the first parameter, T, doesn't seem to matter if it's declared const or not. ---John

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Re: [Boost-users] [MultiIndex] is ordered_non_unique stable?
by John M. Dlugosz 20 Jan '13

20 Jan '13

> The only problem with this is that the behavior is *undocmented*. If you want > to stay legal, use hinted insertion with end() (which will *documentedly* > work for all the ordered_non_unique indices of your container, not only the one > you happen to be doing for the insertion.) > > Joaqu?n M L?pez Mu?oz > Telef?nica Digital > > > That is very interesting. The wording is kind of strange though: "If succesful, insertion happens as close as possible to the location just prior to |position|." I wonder if stability was the intention? Thank you very much for your analysis of the code. ---John

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Help a novice today getting started with regex.hpp
by Neil Sutton 20 Jan '13

20 Jan '13

Please can someone tell me the best place to start studying how to write and use boost::regex.hpp? Is there any documentation or tutorial that is easier for a novice to understand than the standard distribution documentation?

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