June 2008 - Boost - lists.boost.org

Mac OS universal builds: testers needed
by Mat Marcus 25 Jul '08

25 Jul '08

I've made a number of changes to my universal-binary supporting darwin.jam patch (shipping with the Adobe Source Library) in order to address the concerns raised by Rene and others at http://svn.boost.org/trac/boost/ticket/989 : My current version supports invocations like: bjam architecture={combined,x86,power} link={shared,static} address-model={64,32} That is, universal builds are now supported, along with 64 bit builds. I'd like to ask for the help from a few volunteers who'd be willing to test it out, before I submit my patch for consideration. Anyone interested in helping me test it? If so, please contact me off list and I'll send you a couple of boost build files to replace. I still have a bit of cleanup to do. Specifically, on the mac, if a build doesn't specify an -arch parameter, the architecture (and perhaps the address model) of the host machine is used. I'm not really comfortable with the same folder path meaning different things on different machines. So, I plan to do something like the following in darwin.jam (in invented pseudo code) SWITCH(on result of /usr/bin/arch) { # host machine's architecture CASE(ppc) use <architecture>power/<address-model>32 as the default CASE(i386) use <architecture>x86/<address-model>32 as the default CASE(ppc64) use <architecture>power/<address-model>64 as the default CASE(x86_64) use <architecture>x86/<address-model>64 as the default DEFAULT error, unknown arch Thanks, Mat

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Re: [boost] Is our subversion server/archive 1.5 yet?
by Douglas Gregor 18 Jul '08

18 Jul '08

On Sun, 2008-06-29 at 16:12 -0400, Daryle Walker wrote: > Last week, a was bouncing around sites and found out that Subversion > 1.5.0 has gone final. I've downloaded it because I want to try its > built-in merging support (to fix up Boost.Integer in a branch). Has > our subversion system been updated to 1.5? No, we're still using Subversion 1.4 on the server. > Obviously, if the client and server use subversion versions 1.x and > 1.y respectively, the transactions will proceed as the lower of those > versions. Therefore, both individual clients and the server must be > at least the 1.5 level to use built-in merging. There's another > requirement, though: if the server is upgraded to 1.5, the > repositories it manages aren't automatically upgraded. If a > repository isn't upgraded to the 1.5 format, then the server will act > in 1.4-compatibility mode as needed. > > Is there a schedule for these upgrades to be done (if not done > already)? Is it possible to tell from the client side which mode a > server/repository uses? I actually don't know how to tell from the client-side which version of Subversion the server is running. As for the upgrade... we're looking into Subversion 1.5, but it appears to be a nontrivial process to perform the upgrade and migrate svnmerge.py merge information appropriately, so we need to read more, do some test runs, check that other projects haven't run into serious problems, etc. So much depends on the Subversion repository that we need to be careful. When we're ready to move, we'll send out an e-mail to the mailing list. - Doug

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Possible MingW ASIO bug with Boost 1.35.0 g++ 4.2.1
by Jason Turner 17 Jul '08

17 Jul '08

Some ASIO test code is crashing in a way that I do not understand. GDB is unable to debug it (no stack available on crash) and the error is a rather obtuse "This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information." Test code which crashes: #include <boost/asio/ip/address.hpp> #include <iostream> int main() { std::cout << boost::asio::ip::address::from_string("1.1.2.3") << std::endl; } By changing the asio file included, the code no longer crashes: #include <boost/asio.hpp> #include <iostream> int main() { std::cout << boost::asio::ip::address::from_string("1.1.2.3") << std::endl; } This is windowsxp professional, gcc version 4.2.1-dw2. I'm unable to test this on Linux at the moment, so I do not know if it affects other platforms. -Jason -- http://emptycrate.com Games, Programming, Travel & other stuff

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[intrusive] Problem with EDG base compilers in strict Ansi mode.
by Markus Schöpflin 14 Jul '08

14 Jul '08

Hello, currently any_test and doc_any_hook fail on Tru64/CXX with the following errors: cxx: Error: ../boost/intrusive/detail/any_node_and_algorithms.hpp, line 276: class template "boost::intrusive::any_algorithms<VoidPointer>" has no member "unlink_not_available_for_any_hooks" (notmember) any_algorithms<VoidPointer>::unlink_not_available_for_any_hooks(); -----------------------------------^ cxx: Error: ../boost/intrusive/detail/any_node_and_algorithms.hpp, line 283: class template "boost::intrusive::any_algorithms<VoidPointer>" has no member "swap_nodes_not_available_for_any_hooks" (notmember) any_algorithms<VoidPointer>::swap_nodes_not_available_for_any_hooks(); -----------------------------------^ AFAICT this is the only EDG based compiler which tests in strict Ansi mode, adding -strict_ansi to the other EDG based compilers (acc for example) would probably lead to the same error. Attached patch contains a proposed fix for this. It checks for __EDG__ and __STD_STRICT_ANSI to enable the fix and works for me locally. The patch should replace the compile error by a link error, because in strict Ansi mode EDG doesn't allow you to refer to non-existing names. OK to apply? Regards, Markus Index: detail/any_node_and_algorithms.hpp =================================================================== --- detail/any_node_and_algorithms.hpp (revision 46676) +++ detail/any_node_and_algorithms.hpp (working copy) @@ -269,6 +269,11 @@ static bool unique(const_node_ptr node) { return 0 == node->node_ptr_1; } + +#if defined(__EDG__) && defined(__STD_STRICT_ANSI) + static void unlink(node_ptr); + static void swap_nodes(node_ptr l, node_ptr r); +#else static void unlink(node_ptr) { //Auto-unlink hooks and unlink() call for safe hooks are not @@ -282,6 +287,7 @@ //what algorithm they must use from unlink them from the container any_algorithms<VoidPointer>::swap_nodes_not_available_for_any_hooks(); } +#endif }; } //namespace intrusive

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[thread] lockable traits and concepts classes adding proposal
by vicente.botet 14 Jul '08

14 Jul '08

Hello boosters , While writtig a generic library I have needed some lockable traits and concepts to be chacked with BCCL. If you think that these classes are of general use it will be a pleasure for me, if Anthony accepts, to included them on the Boost.Thread library. Otherwise I will left them in my Sync library. For the moment all is defined in a sync (as synchronization) namespace and directory but this is without importance. Attached a short introduction (in quickbook format- sorry I can not attach the html file) as well as the header files (which should with gcc 3.4 on cygwin) Of course all this is subject to discusion, naming and file structure changes, ... For each one of the mutex in the thread library, we need to * make the mutex inherit from the helper lock_traits_base or * have nested typedefs or * specialize each one of the traits templates As an external library I have do this in a non-intrusive way as for example: template<> struct timed_interface_tag<boost::mutex> { typedef hasnt_timed_interface_tag type; }; template<> struct reentrancy_tag<boost::mutex> { typedef non_recursive_tag type; }; template<> struct category_tag<boost::mutex> { typedef exclusive_lock_tag type; }; template<> struct scope_tag<boost::mutex> { typedef multi_threaded_tag type; }; But if included in the Thread library it will be better to use one of the intrusive methods. I have also defined other classes that could be of general interest. * A make_lockable class will make Lockable/ShareLocakble/UpgradeLocable the derived class depending on the Lock parameter. This class could be the base of a monitor class. It can be used as follows: class X : public make_lockable<boost::mutex> { } X x; unique_lock<X> lock(x); * a ..._synchronization_family set of classes that can be used as follows: template <class SyncFamily> message_queue; typedef message_queue<thread_synchonization_family> my_mt_message_queue; typedef message_queue<null_synchonization_family> my_st_message_queue; The null_synchonization_family needs a null_mutex and a null_condition classes. There is already something similar in Boost::Interprocess. * To finish, I'm working on a filter_matching_lockables meta-function which take as parameter a vector of lockables types and will filter the lockables types not satisfying a list of traits. The use shoul be somthing like typedef filter_matching_lockables<vector<boost::mutex, boost::recursive_mutex, ...>, mpl::and_<is_exclusive_lock<_>, mpl::not_<is_recursive_lock<_> > >::type candidates. and a find_best_lock which choose between the lockables given as parameter the best one following a given criteria. Of course, there is yet a lot of work to do, add lock concepts, lockable and lock concept traits, document, tests, document, tests ... between others. As you see there is nothing new, neither complex, only some helper classes making easier the construction of higher abstraction levels, and that currently are missing in boost. Have a good code reading and please let me know what do you think. _____________________ Vicente Juan Botet Escriba

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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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[constrained_value] Formal review request
by Robert Kawulak 11 Jul '08

11 Jul '08

Dear Boosters, I'm glad to say the Boost Constrained Value library is finally ready for a formal review. To remind what this library is about, an excerpt from the motivation section of the documentation is attached at the bottom of this message. Jeff, you volunteered to be the review manager - is your proposition still up to date? If so, I'd be thankful if you could do the work. ;-) The code and documentation can be downloaded here: http://rk.go.pl/f/constrained_value.zip The documentation is also available online here: http://rk.go.pl/r/constrained_value The only thing that's missing is test programs - I will try to add them during/after the review. The changes made since previous version: - rewritten the documentation at some points and added tutorial, - no more value generators - direct types or MPL integral constants are used instead, - bounded types use bounds exclusion instead of inclusion (so bounds are included by default in all cases), - changed order and default values of some of template parameters, - removed throw_verbose_exception error policy, - made other minor fixes and improvements. As always, feedback is welcome. Best regards, Robert Kawulak FROM THE MOTIVATION SECTION OF THE DOCUMENTATION: The Boost Constrained Value library contains class templates useful for creating constrained objects. A simple example is an object representing an hour of a day, for which only integers from the range [0, 23] are valid values: bounded_int<int, 0, 23>::type hour; hour = 20; // OK hour = 26; // exception! Behavior in case of assignment of an invalid value can be customized. For instance, instead of throwing an exception as in the example above, the value may be adjusted to meet the constraint: wrapping_int<int, 0, 255>::type buffer_index; buffer_index = 257; // OK: adjusts the value to fit in the range by wrapping it assert( buffer_index == 1 ); The library doesn't focus only on bounded objects as in the examples above -- virtually any constraint can be imposed by using a predicate: // constraint (a predicate) struct is_odd { bool operator () (int i) const { return (i % 2) != 0; } }; // and the usage is as simple as: constrained<int, is_odd> odd_int = 1; odd_int += 2; // OK ++odd_int; // exception! The library has a policy-based design to allow for flexibility in defining constraints and behavior in case of assignment of invalid values. Policies may be configured at compile-time for maximum efficiency or may be changeable at runtime if such dynamic functionality is needed.

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[Boost.Log1]: Bug in boost/log/detail/ts_posix.hpp
by Jens Seidel 09 Jul '08

09 Jul '08

Hi, I know that version 1 of John's logging library was never accepted and is probably not wildly used anymore nevertheless I found a nasty bug in it. It's strange but even after applying valgrind I found initially not the reason (probably I just assumed John's code is OK and it's something else) and it took some time until I resolved it. OK, for all users of this lib here is the patch: boost/log/detail/ts_posix.hpp: @@ -51,7 +51,7 @@ mutex & operator = ( const mutex & Not_Implemented); mutex( const mutex & From); public: - mutex() : m_mutex() { + mutex() : m_mutex(), m_count(0) { pthread_mutexattr_t attr; int res = pthread_mutexattr_init(&attr); assert(res == 0); I haven't checked whether this occurs in version 2 as well. Jens

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[test][darwin][trunk] using some undefined signal macros on Power PC
by JOAQUIN M. LOPEZ MUÑOZ 07 Jul '08

07 Jul '08

Hello, I guess it is pretty apparent by now, but Boost.Test is causing a lot of regressions in the Sandia-darwin-ppc regression runner with the following: http://tinyurl.com/689u7x ../boost/test/impl/execution_monitor.ipp: In member function 'void boost::detail::system_signal_exception::report() const': ../boost/test/impl/execution_monitor.ipp:292: error: 'ILL_ILLOPN' was not declared in this scope ../boost/test/impl/execution_monitor.ipp:297: error: 'ILL_ILLADR' was not declared in this scope ../boost/test/impl/execution_monitor.ipp:312: error: 'ILL_PRVREG' was not declared in this scope ../boost/test/impl/execution_monitor.ipp:317: error: 'ILL_COPROC' was not declared in this scope ../boost/test/impl/execution_monitor.ipp:322: error: 'ILL_BADSTK' was not declared in this scope ../boost/test/impl/execution_monitor.ipp:332: error: 'FPE_INTDIV' was not declared in this scope ../boost/test/impl/execution_monitor.ipp:337: error: 'FPE_INTOVF' was not declared in this scope ../boost/test/impl/execution_monitor.ipp:367: error: 'FPE_FLTSUB' was not declared in this scope ../boost/test/impl/execution_monitor.ipp:397: error: 'BUS_ADRERR' was not declared in this scope ../boost/test/impl/execution_monitor.ipp:402: error: 'BUS_OBJERR' was not declared in this scope AFACIS <signal.h> does not define these macros in Power PC architectures, further confirmation of this fact here http://source.winehq.org/source/dlls/ntdll/signal_powerpc.c I guess it's easy enough to conditionally #define the offending parts out relying on defined(__POWERPC__). I'd propose a patch mysel but I don't have the appropriate environment to test locally with. And unfortunately we don't have a Darwin/PPC champion yet: http://svn.boost.org/trac/boost/wiki/PlatformChampions HTH, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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[utility/swap] Okay to add array support to Boost.Swap (sandbox/swap)?
by Niels Dekker - mail address until 2008-12-31 06 Jul '08

06 Jul '08

Hi Joe, hi Steven, Would it be okay to you if we would add support for array types to the Boost.Swap utility that is located in the sandbox? I'm asking now, because I wrote an issue, asking the C++ Standards Committee to add an overload of std::swap for array types. And Howard Hinnant just mailed me the other day that the issue has reached status Ready. :-) LWG issue 809, "std::swap should be overloaded for array types" http://home.twcny.rr.com/hinnant/cpp_extensions/issues_preview/lwg-active.h… Of course, it will still take a while before STL implementations will actually add such an std::swap overload. It isn't yet part of the Standard, officially. So I would very much appreciate if boost::swap would already start supporting array types. And I think it would be helpful when implementing swap member functions for templates like boost::value_initialized<T>. Array support could easily be added to swap/boost/utility/swap.hpp (http://svn.boost.org/trac/boost/browser/sandbox/swap/boost/utility/swap.hpp) by overloading boost_swap_impl::swap_impl, as follows: template<class T, std::size_t N> void swap_impl(T (& left)[N], T (& right)[N]) { for (std::size_t i = 0; i < N; ++i) { ::boost_swap_impl::swap_impl(left[i], right[i]); } } Please tell me what you think. I do have SVN write access, so I wouldn't mind committing the necessary changes. :-) Kind regards, -- Niels Dekker http://www.xs4all.nl/~nd/dekkerware Scientific programmer at LKEB, Leiden University Medical Center

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