August 2007 - Boost-users - lists.preview.boost.org

[DateTime] Functions parsing date/time values from wstring missing?
by Boris 07 Aug '07

07 Aug '07

According to http://www.boost.org/doc/html/date_time/details.html#date_time.changes there have been functions added to Boost.DateTime (between Boost 1.31 to 1.32) to convert date and time classes to wstring. However I can't find any functions to parse date and time values from wstring. There is for example to_iso_extended_wstring() but no from_simple_wstring(). Am I missing something? Boris

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[boost][graph] write_graphviz problem
by David Callu 07 Aug '07

07 Aug '07

Hi, I try to write my graph to std::cout with boost::write_graphviz. In the example boost/libs/graph/example/graphviz.cpp, the graph used is a boost::adjacency_list<vecS, vecS, directedS, property<vertex_name_t, std::string>, property<edge_weight_t, double> > and all work fine. my graph is a boost::adjacency_list<listS, listS, bidirectedS, property<my_vertex_t, my_vertex>, property<my_edge_t, my_edge>, property<my_graph_t, my_graph> , listS > If a do "write_graphviz(std::cout, g);" I have a very big error. (why BGL didn't use boost concept check ???) I search in boost code and i found !!! In the file boost/graph/graphviz.hpp line 257 (boost 1.34) "out << get(vertex_id, *i);" so write_graphviz function get the vertex property with the tag of type vertex_id. By default, the type vertex_id is the enum boost::vertex_index which do reference to the type boost::vertex_index_t; This property is intrinsically in the type boost::adjacency_list<vecS, vecS> because the vertex_descriptor is the index of the vertex. And so all work fine with the function write_graphviz With the type boost::adjacency_list<vecS, listS>, this property is not available. TOOOOOO In the complete signature function : void write_graphviz(std::ostream &, const VertexListGraph & g vertexPropertyWrite vpw, EdgePropertyWriter epw, GraphPropertyWriter gpw, VertexID vertex_id); I can give the property_tag to used in the function. But, In opposition to other BGL algorithm which accept an external PropertyMap, this property must be in the graph. And I don't want to add a index property. Question : How to use write_graphviz algorithm with boost::adjacency_list<listS, listS> ? Is there a magic boost property tag to use with a boost::adjacency_list<listS, listS> like the boost::vertex_index_t tag and the boost::adjacency_list<vecS, vecS> is there another solution ?? Thank David Callu

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[Fusion] Is there a version of fusion that works with vanilla 1.34.1?
by Ames, Andreas (Andreas) 07 Aug '07

07 Aug '07

Hi, is there a version of fusion that works with vanilla 1.34.1? TIA, aa -- Andreas Ames | Programmer | Comergo GmbH | ames AT avaya DOT com Sitz der Gesellschaft: Stuttgart Registergericht: Amtsgericht Stuttgart - HRB 22107 Geschäftsführer: Andreas von Meyer zu Knonow, Udo Bühler, Thomas Kreikemeier

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[iterator_adaptor] Accessing base class
by Mark Ruzon 07 Aug '07

07 Aug '07

I have defined an iterator adaptor called skip_iterator. I found that I have to write: skip_iterator() : skip_iterator::iterator_adaptor_(0), m(1) {} rather than skip_iterator() : iterator_adaptor_(0), m(1) {} even though iterator_adaptor_ is a protected typedef inside iterator_adaptor. Will someone explain why I have to qualify the name? Thanks, Mark Ruzon

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order of iterators in multi_index container
by boost＠larroy.com 07 Aug '07

07 Aug '07

Hi I was using multi_index nicely and then I wondered that although iterators are not invalidated when calling replace or modify, could it be that if I'm modifying inside a loop then incrementing the iterator no longer makes it iterate through all elements because of the index reordering? Regards. -- Pedro Larroy Tovar Promax R&D Lab

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Fwd: Re: timeout events in Boost.Statechart
by Andreas Huber 07 Aug '07

07 Aug '07

Hi Chris, > I ended up implementing timeout support with a WM_TIMER handler in > the > parent of the state machine class. States that can have a timeout > event > just pass their timeout duration to the state machine via > context<>, which > in turn calls SetTimer in the parent class. The WM_TIMER handler > adds a > timeout event to the state machine's queue. Does the WM_TIMER handler really add the event to the queue of the state_machine subclass object? If so, then you might have introduced a race condition. WM_TIMER handlers are called in a dedicated thread, right? > Just to comment on the design, it requires that I declare state > classes with > "state" base class instead of simple_state, as I have to perform > the > context<> cast in the constructor/entry of the new state in order > to set up > a timeout. Correct. > Also, like the Camera example, I implemented a > post_event in the > constructor/entry of some states, which also requires derivation > from state, Correct. > and awkward instancing of the event. I don't understand. You mean the special constructor you have to add to the state, right? > Unfortunately, I'm in feasibility testing, and haven't had an > opportunity to > closely examine the implementation. If you think there's something > I'm > missing, please let me know. See above, WM_TIMER should probably not call state_machine.process_event. Instead you should use asynchronous_machine and queue the event through the scheduler, which is thread-safe. > Would using methods (Entry/Exit) > instead of > the constructor/destructor ease some of these problems? This is a somewhat controversical topic. During formal review there were a few people who favored entry() and exit() functions over the current ctor/dtor design. This is related to the debate whether one should initialize everything in the constructor or do (almost) nothing in the constructor and have the client call Init() right after construction. Sure, in our case entry() would be automatically called by the library immediately after construction but it still runs counter to established C++ practice. The problem with entry() is that it forces you to losen your class invariants, e.g. timerId below can no longer be const, since context<Machine>.StartTimer() could no longer be called in the ctor (where access via context would be impossible) but only in entry(). struct MyState : sc::state<MyState, Machine> { int count_; const int timerId_; MyState(my_context ctx) : my_base(ctx), count_(0), timerId_(context<Machine>.StartTimer(3000)) { // additional stuff } ~MyState() { context<Machine>.StopTimer(timerId_); } } Regards, Andreas > On 8/3/07, Andreas Huber <ahd6974-boostorg(a)yahoo.com> wrote: > > > > Hi Chris > > > > > Since timeouts are so common in state machine applications, do > you > > > think it > > > would make sense to support them as a specific reaction type? > > > > The necessary infrastructure for time events is quite > significant, > > see > > > > > <http://www.boost.org/libs/statechart/doc/uml_mapping.html#TimeEvent> > > > > You basically either need an OS that supports timed callbacks, or > > need to implement your own scheduler, which supports the passing > of a > > time at which a given event must be dispatched. Given the lacking > > primitives in C++, both options require significant platform > > abstraction effort. I always had the hope that either > Boost.Thread or > > a futures library would provide such primitives but to my > knowledge > > nothing has so far materialized. I *guess* Asio does offer such > > primitives but I have a hard time to justify that dependency just > for > > a time event implementation. > > > > To cut a long story short, for now you need to implement time > event > > support yourself :-/. > > > > HTH, > > > > Andreas > > > > P.S. I think this information is also interesting for other boost > > users, so unless you object I'll post this message on the > Boost.Users > > list tomorrow. > >

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simple_ls.cpp build issues
by Grattan, Steven 07 Aug '07

07 Aug '07

Hi, I'm new to the boost libraries and wanted to write something that would give me the names of all the entries in a directory in a platform independent way. Having looked at the filesystem facilities provided with boost I decided that this is just what I need and downlaoded simple_ls.cpp just to check I could compile it before going any further. I'm using Microsoft Visual Studio 2005 Express Edition and I get a few compile errors when I tries to build it. Maybe I'm missing something here but the error messages seem to reflect the reality since the items it can't find don't exist in the boost files provided - I'm using boost 1.3.3.1 Here is the output from the compiler: 1>------ Build started: Project: boostFileSystem, Configuration: Debug Win32 ------ 1>Compiling... 1>simple_ls.cpp 1>z:\visual studio 2005\projects\boostfilesystem\boostfilesystem\simple_ls.cpp(51) : error C2039: 'status' : is not a member of 'boost::filesystem::path' 1> x:\3rdpartytools\boost_1_33_1\boost\filesystem\path.hpp(34) : see declaration of 'boost::filesystem::path' 1>z:\visual studio 2005\projects\boostfilesystem\boostfilesystem\simple_ls.cpp(54) : error C2273: 'function-style cast' : illegal as right side of '->' operator 1>z:\visual studio 2005\projects\boostfilesystem\boostfilesystem\simple_ls.cpp(54) : error C2228: left of '.leaf' must have class/struct/union 1>z:\visual studio 2005\projects\boostfilesystem\boostfilesystem\simple_ls.cpp(56) : error C2039: 'is_regular' : is not a member of 'boost::filesystem' 1>z:\visual studio 2005\projects\boostfilesystem\boostfilesystem\simple_ls.cpp(56) : error C2039: 'status' : is not a member of 'boost::filesystem::path' 1> x:\3rdpartytools\boost_1_33_1\boost\filesystem\path.hpp(34) : see declaration of 'boost::filesystem::path' 1>z:\visual studio 2005\projects\boostfilesystem\boostfilesystem\simple_ls.cpp(56) : error C3861: 'is_regular': identifier not found 1>z:\visual studio 2005\projects\boostfilesystem\boostfilesystem\simple_ls.cpp(59) : error C2273: 'function-style cast' : illegal as right side of '->' operator 1>z:\visual studio 2005\projects\boostfilesystem\boostfilesystem\simple_ls.cpp(59) : error C2228: left of '.leaf' must have class/struct/union 1>z:\visual studio 2005\projects\boostfilesystem\boostfilesystem\simple_ls.cpp(64) : error C2273: 'function-style cast' : illegal as right side of '->' operator 1>z:\visual studio 2005\projects\boostfilesystem\boostfilesystem\simple_ls.cpp(64) : error C2228: left of '.leaf' must have class/struct/union 1>z:\visual studio 2005\projects\boostfilesystem\boostfilesystem\simple_ls.cpp(71) : error C2273: 'function-style cast' : illegal as right side of '->' operator 1>z:\visual studio 2005\projects\boostfilesystem\boostfilesystem\simple_ls.cpp(71) : error C2228: left of '.leaf' must have class/struct/union 1>Build log was saved at "file://\\sw620_f\grattans$\Visual Studio 2005\Projects\boostFileSystem\boostFileSystem\Debug\BuildLog.htm" 1>boostFileSystem - 12 error(s), 0 warning(s) ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== Any help would be much appreciated, Steve Grattan This email (including attachments) is confidential and is solely intended for the addressee. Unless you are the addressee, you may not read, use or store this email in any way, or permit others to. If you have received it in error, please contact Visa Europe on +44 (0)20 7937 8111.

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Problem with mpl::joint_view working on two mpl::maps
by Martin Apel 07 Aug '07

07 Aug '07

Hi *, I have two mpl maps like this: typedef map<pair<int_<1>, int_<42> >, pair<int_<2>, int_<43> >, pair<int_<3>, int_<44> > > Map1; typedef map<pair<int_<4>, int_<44> >, pair<int_<5>, int_<45> >, pair<int_<6>, int_<46> > > Map2; I try to join them using "joint_view" as follows: typedef joint_view<Map1, Map2>::type JointMap; which works fine. Then I do std::cout << at<JointMap, int_<2> >::type::value << "\n"; which gives the following compiler error: error: 'value' is not a member of 'boost::mpl::pair<mpl_::int_<3>, mpl_::int_<44> >' I tried this with gcc 3.4.6 and 4.2 under Linux, Boost version is 1.34.0. It seems "at" returns the entry after the searched entry, and not only the right half, but the complete pair. Has anybody got any hints on this? To me it looks like a bug in MPL, but I might be wrong. Best Regards, Martin ____________ Virus checked: AVKB 17.327 from 06.08.2007

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Re: [Boost-users] Boost-users Digest, Vol 1352, Issue 1
by Vial, Florent 07 Aug '07

07 Aug '07

>> I?ve installed Boost Libary 1.34.0 >> I?m working with VS 2005 SP1. >> If I try to include any of the boost *.hpp files I get more than 100 >> errors in the files "memory" and "algorithm". I think this errors >> first >What errors? I think I know which ones. These are cryptic error messages. They happened in my case because of the include order. I work under VS 2005 with SP2 (whcih you should install by the way). Make sure you include the system headers (like windows.h) before the boost headers. Hope this helps, Regards, Florent Arnold & Richter Cine Technik GmbH & Co. Betriebs KG Sitz: Munchen - Registergericht: Amtsgericht Munchen - Handelsregisternummer: HRA 57918 Personlich haftender Gesellschafter: Arnold & Richter Cine Technik GmbH Sitz: Munchen - Registergericht: Amtsgericht Munchen - Handelsregisternummer: HRB 54477 Geschaftsfuhrer: Prof. Dr. Dejan Ilic; Franz Kraus; Jens Schafer Beiratsvorsitzender: Prof. Dr. Hans-Jorg Bullinger

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Problem including hpp Headers
by Wolfgang Issovits 07 Aug '07

07 Aug '07

Hello! I´ve installed Boost Libary 1.34.0 I´m working with VS 2005 SP1. If I try to include any of the boost *.hpp files I get more than 100 errors in the files "memory" and "algorithm". I think this errors first occoured, after installing SP1 for VS. Does anyone has any idea why this errors occour?

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