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Is there a helper function for boost::fusion::vector just as std::make_pair to std::pair?
by Peng Yu 11 Jul '08

11 Jul '08

Hi, Is there a helper function for boost::fusion::vector just as std::make_pair to std::pair? boost::fusion::vector<very_loooooooooooooooooong_type,...,very_loooooooooooooooooong_type> v(...,,...); Suppose I have the above case, where the declaration is very long, I would like a helper function to simplify the above definition. Thanks, Peng

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[serialization][portable-binary archive] Data not byte-swapped across architectures
by Jon Kroll 11 Jul '08

11 Jul '08

Hello: I am attempting to use the boost serialization portable-binary archive. The 2 architectures I am working on are: 1. Intel on MS-Windows/Mac OS X 2. PowerPC on Mac OS X The attached sample code shows that an integer I serialize on PPC and then unserialize on Intel is not byte-swapped. And similarly, an integer I serialize on Intel is not byte-swapped on PPC. It does not appear to be a OS issue, because the data is unserialized properly from a MS-Windows Intel system to a Mac OS X Intel system, and vise versa. Another manifestation of this occurs when I serialize a large container, like a vector for example. The code has an exception because the size of the container is not byte-swapper. I can provide example code for this as well. This experience leads me to believe either: 1. The portable binary is not functioning properly with Mac OS X PPC or 2. I am not using the portable-binary archive properly, either configuration or code. Advise on this issue would be greatly appreciated. Best regards, Jon Kroll Ann Arbor Michigan ========================================================================= BUILD: Windows: MS-Visual Studio 2005 Mac OS X: g++ test_portable_binary.cpp portable_binary_iarchive.cpp portable_binary_oarchive.cpp -o test_portable_binary -I/Volumes/..../boost_1_35_0/ -L/Volumes/..../boost_1_35_0/stage/lib/ -lboost_serialization-mt-1_35 CODE: ======================================================== #include "boost/archive/portable_binary_oarchive.hpp" #include "boost/archive/portable_binary_iarchive.hpp" #include <vector> #include <sstream> #include <fstream> #include <iostream> #include <string> namespace { bool isIntelArch() { char endianTest[2] = { 1, 0 }; return (*(short *) endianTest == 1); } bool isPPCArch() { return !isIntelArch(); } } int main(int argc, char* argv[]) { if (false) // generate test file { std::string fileName; if (isPPCArch()) fileName = "PPC_portableBinaryLargeInt.ser"; else if (isIntelArch()) fileName = "Intel_portableBinaryLargeInt.ser"; int val = 16000; // 0x3E80 std::ofstream os(fileName.c_str(), std::ios::binary); portable_binary_oarchive oa(os); oa & val; return 0; } int unserializedVal = 0; { std::string fileName; if (isPPCArch()) fileName = "Intel_portableBinaryLargeInt.ser"; else if (isIntelArch()) fileName = "PPC_portableBinaryLargeInt.ser"; std::ifstream is(fileName.c_str(), std::ios::binary); portable_binary_iarchive ia(is); ia & unserializedVal; } if (0x3E80 == unserializedVal) { return 0; // This is the correct result! } if (0x803E == unserializedVal) { return -1; // This is an error, the value is not byte-swapped } if (0 == unserializedVal) { return -1; // This is an error, nothing got unserialized } return 0; }

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Concept based overloading and the ODR
by Steven Watanabe 11 Jul '08

11 Jul '08

AMDG I'm looking at two recent posts: http://comments.gmane.org/gmane.comp.lib.boost.devel/177370 http://comments.gmane.org/gmane.comp.lib.boost.user/37476 Either of these is fine by itself, but putting them both together makes it very easy to cause silent ODR problems. For example in translation unit a.cpp we #include "boost/tuple/tuple_io.hpp" and translation unit b.cpp we forget. Then, along comes boost::any which detects operator<< in translation unit a.cpp, but uses its default in translation unit b.cpp. Ka-Boom. This is not a huge problem at the moment, because it's quite difficult to make the detection bullet-proof, but I'm very concerned because C++0x concepts are supposed to make such overloading easy. In Christ, Steven Watanabe

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How to convert a vector of base classes to template based code?
by Peng Yu 11 Jul '08

11 Jul '08

Hi, The following program uses virtual functions. Essentially I need to go through all the pairs in 'v'. Since I have already know what are in v at compile time. I would like to convert the dynamic polymorphism to template. Therefore, the runtime would be better. I think this should be done with the help of boost::mpl. But I'm not sure how to do it. Would you please help me? Thanks, Peng #include <iostream> #include <vector> #include <boost/shared_ptr.hpp> struct shape { virtual void show_me() const = 0; virtual ~shape() { } }; struct square : public shape { void show_me() const { std::cout << "square"; } }; struct circle : public shape { void show_me() const { std::cout << "circle"; } }; struct triangle : public shape { void show_me() const { std::cout << "triangle"; } }; int main() { std::vector<boost::shared_ptr<shape> > v; { boost::shared_ptr<shape> s(new square); v.push_back(s); } { boost::shared_ptr<shape> s(new circle); v.push_back(s); } { boost::shared_ptr<shape> s(new square); v.push_back(s); } { boost::shared_ptr<shape> s(new triangle); v.push_back(s); } for(std::vector<boost::shared_ptr<shape> >::const_iterator it = v.begin(); it != v.end(); ++ it) { for(std::vector<boost::shared_ptr<shape> >::const_iterator it2 = it + 1; it2 != v.end(); ++ it2) { (*it)->show_me(); std::cout << " vs. "; (*it2)->show_me(); std::cout << std::endl; } } }

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Review Wizard Status Report for May 2008
by Ronald Garcia 11 Jul '08

11 Jul '08

========================================== Review Wizard Status Report for May 2008 ========================================== News ==== December 7, 2007 - Forward Library Accepted - Awaiting SVN December 16 - Unordered Containers Library Accepted - In SVN December 21 - Factory Library Accepted - Awaiting SVN January 13, 2008 - Switch Library Accepted Provisionally - Awaiting submission for mini review January 18 - Singleton Library Rejected - Awaiting resubmission, John Torjo has already volunteered to manage the next review January 30 - Flyweight Library Accepted - Awaiting SVN February 13 - Logging Library Rejected - Awaiting resubmission for new review, John Torjo has already resubmitted and Gennadiy Rozental has again volunteered to manage the review February 27 - Floating Point Utilities Library Accepted - Awaiting SVN March 14 - Proto Library Accepted - Exists as a component in Xpressive, but not yet as a separate library April 20 - Egg review completed - Results pending May 7 - Scope Exit Library Accepted - Awaiting SVN Older Issues ============ The binary_int library, accepted in October 2005 has not yet been submitted to SVN. The authors are strongly encouraged to contact the review wizards The Quantitative Units library, accepted in April 2007 has not yet been submitted to SVN The Globally Unique Identifier library, accepted provisionally in May 2007 has not yet been submitted for mini-review and full acceptance The Time Series Library, accepted in August 2007 has not yet been submitted to SVN The Accumulators library, accepted in February 2007 is in SVN The Exception library, accepted in October 2007 is in SVN The Scope Exit review report had not been submitted by the review manager. John Phillips stepped in as substitute review manager and produced a report For libraries that are still waiting to get into SVN, please get them ready and into the repository. The developers did some great work making the libraries, so don't miss the chance to share that work with others. Also notice that the review process page has been updated with a section on rights and responsibilities of library submitters. For the Scope Exit review, we would like to publicly apologize to Alexander Nasonov for how long this has languished without a report. The review wizards will work to make sure this doesn't happen any more. General Announcements ===================== As always, we need experienced review managers. In the past few months there have been a large number of reviews, but the flow of high quality submissions is just as big, so manage reviews if possible and if not please make sure to watch the review schedule and participate. Please take a look at the list of libraries in need of managers and check out their descriptions. In general review managers are active boost participants or library contributors. If you can serve as review manager for any of them, email Ron Garcia or John Phillips, "garcia at cs dot indiana dot edu" and "phillips at mps dot ohio-state dot edu" respectively. A link to this report will be posted to www.boost.org. If you would like us to make any modifications or additions to this report before we do that, please email Ron or John. If you're a library author and plan on submitting a library for review in the next 3-6 months, send Ron or John a short description of your library and we'll add it to the Libraries Under Construction below. We know that there are many libraries that are near completion, but we have hard time keeping track all of them. Please keep us informed about your progress. Review Queue ============ * Finite State Machines * Property Map (fast-track) * Graph (fast-track) * Lexer * Thread-Safe Signals * Boost.Range (Update) * Shifted Pointer * DataFlow Signals * Logging * Futures (Braddock Gaskill) * Futures (Anthony Williams) * Join (Yigong Liu) * Pimpl (Vladimir Batov) -------------------- Finite State Machines --------------------- :Author: Andrey Semashev :Review Manager: Martin Vuille :Download: `Boost Sandbox Vault <http://tinyurl.com/yjozfn>`__ :Description: The Boost.FSM library is an implementation of FSM (stands for Finite State Machine) programming concept. The main goals of the library are: * Simplicity. It should be very simple to create state machines using this library. * Performance. The state machine infrastructure should not be very time and memory-consuming in order to be applicable in more use cases. * Extensibility. A developer may want to add more states to an existing state machine. A developer should also be able to specify additional transitions and events for the machine with minimum modifications to the existing code. Property Map (fast-track) ------------------------- :Author: Andrew Sutton :Review Manager: Jeremy Siek :Download: http://svn.boost.org/svn/boost/sandbox/graph-v2 :Description: A number of additions and modifications to the Property Map Library, including: * A constant-valued property map, useful for naturally unweighted graphs. * A noop-writing property map, useful when you have to provide an argument, but just don't care about the output. * See `ChangeLog <http://svn.boost.org/trac/boost/browser/sandbox/ graph-v2/libs/property_map/ChangeLog>`__ for details. Graph (fast-track) ------------------ :Author: Andrew Sutton :Review Manager: Jeremy Siek :Download: http://svn.boost.org/svn/boost/sandbox/graph-v2 :Description: A number of additions and modifications to the Graph Library, including: * Two new graph classes (undirected and directed) which are intended to make the library more approachable for new developers * A suite of graph measures including degree and closeness centrality, mean geodesic distance, eccentricity, and clustering coefficients. * An algorithm for visiting all cycles in a directed graph (Tiernan's from 1970ish). It works for undirected graphs too, but reports cycles twice (one for each direction). * An algorithm for visiting all the cliques a graph (Bron&Kerbosch). Works for both directed and undirected. * Derived graph measures radius and diameter (from eccentricity) and girth and circumference (from Tiernan), and clique number (from Bron&Kerbosch). * An exterior_property class that helps hides some of the weirdness with exterior properties. * run-time and compile-time tests for the new algorithms. * a substantial amount of documentation * Graph cores, implemented by David Gleich (@Stanford University) * Deterministic graph generators - capable of creating or inducing specific types of graphs over a vertex set (e.g., star graph, wheel graph, prism graph, etc). There are several other specific types that could be added to this, but I haven't had the time just yet. Lexer ----- :Author: Ben Hanson :Review Manager: Eric Neibler :Download: `Boost Sandbox Vault <http://boost-consulting.com/vault/ index.php? action=downloadfile&filename=boost.lexer.zip&directory=Strings%20-% 20Text%20Processing&>`__ :Description: A programmable lexical analyser generator inspired by 'flex'. Like flex, it is programmed by the use of regular expressions and outputs a state machine as a number of DFAs utilising equivalence classes for compression. Thread-Safe Signals ------------------- :Author: Frank Hess :Review Manager: Need Volunteer :Download: `Boost Sandbox Vault <http://www.boost-consulting.com/ vault/index.php?&direction=0&order=&directory=thread_safe_signals>`__ :Description: A thread-safe implementation of Boost.Signals that has some interface changes to accommodate thread safety, mostly with respect to automatic connection management. Boost.Range (Update) -------------------- :Author: Neil Groves :Review Manager: Needed :Download: `Boost Sandbox Vault <http://www.boost-consulting.com/ vault/index.php?action=downloadfile&filename=range_ex.zip&directory=>`__ :Description: A significant update of the range library, including range adapters. Shifted Pointer --------------- :Author: Phil Bouchard :Review Manager: Needed :Download: `Boost Sandbox Vault <http://www.boost-consulting.com/ vault/index.php?&direction=0&order=&directory=Memory>`__ :Description: Smart pointers are in general optimized for a specific resource (memory usage, CPU cycles, user friendliness, ...) depending on what the user need to make the most of. The purpose of this smart pointer is mainly to allocate the reference counter (or owner) and the object itself at the same time so that dynamic memory management is simplified thus accelerated and cheaper on the memory map. DataFlow Signals ---------------- :Author: Stjepan Rajko :Review Manager: Needed :Download: http://dancinghacker.com/code/dataflow/ :Description: Dataflow is a generic library for dataflow programming. Dataflow programs can typically be expressed as a graph in which vertices represent components that process data, and edges represent the flow of data between the components. As such, dataflow programs can be easily reconfigured by changing the components and/or the connections. Logging ------- :Author: John Torjo :Review Manager: Gennadiy Rozental :Download: http://torjo.com/log2/ :Description: Used properly, logging is a very powerful tool. Besides aiding debugging/testing, it can also show you how your application is used. The Boost Logging Library allows just for that, supporting a lot of scenarios, ranging from very simple (dumping all to one destination), to very complex (multiple logs, some enabled/some not, levels, etc). It features a very simple and flexible interface, efficient filtering of messages, thread-safety, formatters and destinations, easy manipulation of logs, finding the best logger/filter classes based on your application's needs, you can define your own macros and much more! Futures ------- :Author: Braddock Gaskill :Review Manager: Needed :Download: http://braddock.com/~braddock/future/ :Description: The goal of the boost.future library is to provide a definitive future implementation with the best features of the numerous implementations, proposals, and academic papers floating around, in the hopes to avoid multiple incompatible future implementations in libraries of related concepts (coroutines, active objects, asio, etc). This library hopes to explore the combined implementation of the best future concepts. Futures ------- :Author: Anthony Williams :Review Manager: Needed :Download: http://www.justsoftwaresolutions.co.uk/files/ n2561_future.hpp (code) http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/ n2561.html (description) :Description: This paper proposes a kind of return buffer that takes a value (or an exception) in one (sub-)thread and provides the value in another (controlling) thread. This buffer provides essentially two interfaces: * an interface to assign a value as class promise and * an interface to wait for, query and retrieve the value (or exception) from the buffer as classes unique_future and shared_future. While a unique_future provides move semantics where the value (or exception) can be retrieved only once, the shared_future provides copy semantics where the value can be retrieved arbitrarily often. A typical procedure for working with promises and futures looks like: * control thread creates a promise, * control thread gets associated future from promise, * control thread starts sub-thread, * sub-thread calls actual function and assigns the return value to the promise, * control thread waits for future to become ready, * control thread retrieves value from future. Also proposed is a packaged_task that wraps one callable object and provides another one that can be started in its own thread and assigns the return value (or exception) to a return buffer that can be accessed through one of the future classes. With a packaged_task a typical procedure looks like: * control thread creates a packaged_task with a callable object, * control thread gets associated future from packaged_task, * control thread starts sub-thread, which invokes the packaged_task, * packaged_task calls the callable function and assigns the return value, * control thread waits for future to become ready, * control thread retrieves value from future. Notice that we are in the unusual position of having two very different libraries with the same goal in the queue at the same time. The Review Wizards would appreciate a discussion of the best way to hold these two reviews to produce the best possible addition to Boost. Join ---- :Author: Yigong Liu :Review Manager: Needed :Download: http://channel.sourceforge.net/ :Description: Join is an asynchronous, message based C++ concurrency library based on join calculus. It is applicable both to multi-threaded applications and to the orchestration of asynchronous, event-based applications. It follows Comega's design and implementation and builds with Boost facilities. It provides a high level concurrency API with asynchronous methods, synchronous methods, and chords which are "join-patterns" defining the synchronization, asynchrony, and concurrency. Pimpl ----- :Author: Vladimir Batov :Review Manager: Needed :Download: `Boost Sandbox Vault <http://www.boost-consulting.com/ vault/index.php?action=downloadfile&filename=Pimpl.zip&directory=&>`__ http://www.ddj.com/cpp/205918714 (documentation) :Description: The Pimpl idiom is a simple yet robust technique to minimize coupling via the separation of interface and implementation and then implementation hiding. This library provides a convenient yet flexible and generic deployment technique for the Pimpl idiom. It's seemingly complete and broadly applicable, yet minimal, simple and pleasant to use. Libraries under development =========================== Please let us know of any libraries you are currently developing that you intend to submit for review.

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Interest in properties library?
by Sergey Sadovnikov 11 Jul '08

11 Jul '08

Hello All, Would there be any interest in another C++ properties implementation? I know that boost sandbox already contains properties library. But I can offer another implementation of such library with some advantages like this: - Simple properties set initialization. Only one call from the constructor: class SomeClass { public: //... SomeClass() : properties__(this) {/*...*/} //... }; - Many kins of properties. Now implemented: Simple properties similar to datamembers. Properties bindable to getter/setter methods of container class. Properties bindable to arbitrary methods. Index properties with up to three levels of indirection. - Properties could be "abstract" and need implementation in derived classes - In-place initialization of simple properties. For example: PROPERTY_I(int, ContainerSize, 10) - Generic runtime access to the properties via names: SomeClassWithProps c; int val; c.properties__.invoke_get("ContainerSize", var(val) = boost::lambda::_1); c.properties__.invoke_set("ContainerSize", 20); - Runtime enumeration of properties: // Property visitor function template<typename P> void PropertyEnumerator(const std::string& propertyName, P SomeClassWithProps::* propInfo) { //... ] // Properties enumeration: SomeClassWithProps::properties__::enum_s(PropertyEnumerator); - Simple serialization of properties: template<typename Ar> void serialize(Ar& ar, const unsigned int ver) { ar & properties__; } - Quite simple definition in class. A piece of code from real project: // Example of abstract properties definition in the base class: class IPlayerCraft : public IAirObject { public: IPlayerCraft() : properties__(this) {;} virtual ~IPlayerCraft(){} // Craft status enum ECRAFTSTATUS { csREADY =0, csFLYING, csREPAIRING, csREFUELING, csREARMING, csTRANSFERING, csMAXCOUNT }; PROPERTIES(IPlayerCraft, // Craft name ABSTRACT_RW_PROPERTY(std::wstring, Name) // Static craft info ABSTRACT_RO_PROPERTY(SCraftInfo const*, Info) // Craft home base ABSTRACT_RO_PROPERTY(IBase const*, HomeBase) // Is craft on the base? ABSTRACT_RO_PROPERTY(bool, IsOnTheBase) // Craft status ABSTRACT_RO_PROPERTY(ECRAFTSTATUS, Status) // Current craft speed ABSTRACT_RO_PROPERTY(TPARAM, Speed) // Craft weapon ABSTRACT_INDEX_PROPERTY(IItem*, CraftWeapon, 1, (CraftSlotCoord)) // Craft weapon ammo ABSTRACT_RO_INDEX_PROPERTY(TPARAM, CraftWeaponAmmo, 1, (CraftSlotCoord)) ); //... }; // Implementation class class PlayerCraft : public IPlayerCraft { public: PlayerCraft(SCraftInfo const*, Player* player); ~PlayerCraft(); PROPERTIES(PlayerCraft, IMPLEMENT_PROPERTY(IPlayerCraft, PROPERTY(std::wstring, Name)) IMPLEMENT_PROPERTY(IPlayerCraft, PROPERTY(SCraftInfo const*, Info)) IMPLEMENT_PROPERTY(IPlayerCraft, RO_PROPERTY(IBase const*, HomeBase, GetHomeBase)) IMPLEMENT_PROPERTY(IPlayerCraft, PROPERTY(bool, IsOnTheBase)) IMPLEMENT_PROPERTY(IPlayerCraft, PROPERTY_I(ECRAFTSTATUS, Status, csTRANSFERING)) IMPLEMENT_PROPERTY(IPlayerCraft, PROPERTY_I(TPARAM, Speed, 0)) IMPLEMENT_PROPERTY(IPlayerCraft, INDEX_PROPERTY(IItem*, CraftWeapon, 1, (CraftSlotCoord), GetCraftWeapon, SetCraftWeapon)) IMPLEMENT_PROPERTY(IPlayerCraft, RO_INDEX_PROPERTY(TPARAM, CraftWeaponAmmo, 1, (CraftSlotCoord), GetCraftWeaponAmmo)) ); // ... IBase const* GetHomeBase() const {return m_HomeBase;} private: // ... IItem* GetCraftWeapon(int slotId) const; void SetCraftWeapon(int slotId, IItem* weapon); TPARAM GetCraftWeaponAmmo(int slotId) const; }; As you can see, properties definition based on boost::preprocessor. It allows to implement quite complex background (with many special abilities) for quite simple front-end. It is assumed what access to the properties in many cases is same as access to the datamember: PlayerCraft craft; std::string craft_name = craft.Name; //... IItem* weapon = craft.CraftWeapon[1]; And there is special access form needs in some cases: craft.Name(); or craft.Name.get(); If there is an interest in such properties implementation I could start prepare code for formal library review. -- Best Regards, Sergey mailto:flex_ferrum@artberg.ru

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Recursive iterator/range adaptors
by Mathias Gaunard 11 Jul '08

11 Jul '08

The traversal library that has been discussed allows tree-like traversal of structures using a functional approach. I suggest an alternative approach: a range-based one. It certainly has limitations: ranges are monomorphic. So you can only do it if is_same< typename range_value<Range>::type, typename range_value< typename range_value<Range> >::type >. However, it would be very practical to use, since you could simply use a foreach loop to perform depth-first search and stop iteration whenever you like. Also, it is lazy and you can combine it easily with other range adaptors (filtering, transforming...) or algorithms. For performance, one would need to provide a way to get the father range of a given range. Maybe that's the occasion to create a new concept. Otherwise iterators will need to have their own stack. Did anyone ever work on that? Does it look like a good idea?

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[pool] segfault
by Phil Bouchard 11 Jul '08

11 Jul '08

I was testing my own "shifted_ptr_test2.cpp" on RHEL 4.5 using Gcc 3.4.6 and the following object declared in "sh_owned_base_nt.hpp" caused a segmentation violation inside its destructor. It doesn't seem to happen on Windows, just Linux: pool owned_base::pool_; // derives from boost::pool<> Thanks, -Phil

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[graph] generating CSR graph from undirected
by Mojmir Svoboda 11 Jul '08

11 Jul '08

hello, i suspect there is something wrong with assign routine in compressed_sparse_row_graph.hpp. when i am constructing directed csr from undirected one via // From any graph (slow and uses a lot of memory) // Requires IncidenceGraph, a vertex index map, and a vertex(n, g) function // Internal helper function template<typename Graph, typename VertexIndexMap> void assign(const Graph& g, const VertexIndexMap& vi, vertices_size_type numverts, edges_size_type numedges) { inherited_vertex_properties::resize(numverts); m_rowstart.resize(numverts + 1); m_column.resize(numedges); it overwrites non-allocated memory, because the number of edges is in fact doubled.. is it an imperfection or am i doing something stupid? have a nice day, mojmir

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Boost DateTime package question
by Mohnish Kodnani 10 Jul '08

10 Jul '08

Hi All, I have a question regarding the boost DateTime package. In our application we have to support storing time from various time zone in UTC and we need to know DST of various timezones. We are currently using standard C runtime libraries for this purpose on various platforms like windows , linux, aix, hpux. My question, Recently there has been a need to store dates prior to epoch in our system and this causes problems since none of the standard C runtime libraries support dates prior to EPOCH. We are also interested in DST settings prior to EPOCH, since in our experiments it looks like Java knows DST till 1942 or in its vicinity, however C only deals with dates after epoch. Our server is in C++ and client in Java, so we have issues here when client sends a date prior to 1942 and we have to store its UTC value, we cannot do this since C runtime mktime like functions dont work. Does Boost DateTime package provide this functionality, if not is that in the plans. >From what I read so far it looks like this package does not have this functionality, but has the functionality to create our own rules, however this is difficult considering all countries around the world, it would be good if we had something similar to C runtime. Please let me know. thanks Mohnish

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