February 2005 - Boost - lists.boost.org

Singleton/Multiton Longevity
by Jason Hise 04 Feb '05

04 Feb '05

Just a status update on the singleton/multiton library, so that people know I am still alive ;). After much chaos trying to write a multiton longevity lifetime policy, I had the sudden realization that both singletons and multitons should be able to play nicely together. Thus, I am writing a single(ton) class to manage a priority queue of shared_ptrs to nodes. The longevity policies will derive privately from their respective dependency policies, and create their own derived node types which hold dependencies. As the inheritance is private, these will be the only dependencies in existence. Both multitons and singletons will be destroyed as the dependency-holding nodes are popped in the destructor of the instance registry, which itself will have a static dependency to ensure existence for the entire lifetime of the program. Thoughts and suggestions, as always, are welcome. -Jason

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Semaphore in boost.Thread
by Serguei Kolos 04 Feb '05

04 Feb '05

Hello As far as I know semaphores have been removed from the boost.Thread library. But the point is that on many platforms (Linux for example) semaphore is the only async-signal safe synchronization object. Does anybody know how to synchronize signal handlers with the other programming threads without semaphores? Cheers, Sergei

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A swapping implementation of the C++ library
by Chris Jefferson 04 Feb '05

04 Feb '05

While this isn't strictly related to the development of boost, I believe it may be interesting to developers of boost, and I would also be very interested in hearing any opinions (good and bad) from users and developers of boost. I am currently in the process of implementing all applicable (sort, rotate, partition, etc..) functions in the C++ standard library using only calls to iter_swap. Obviously for those classes with expensive copies and cheap swaps (list, vector, map, set, etc) this is a big win, however it unfortunatly can be slightly slower for classes and types which fall on the basic definition of swap. Therefore there will be an implementation-specific type trait defined (name to be decided) which can be defined to enable the swapping versions of functions. I'm implementing much of this for my own personal usage, but I hope to submit the code to libstdc++-v3 (g++'s implementation of the c++ standard library). While this may not be quite as general as the ideas of "move symantics", it has the advantage of being implementable now, and providing some significant improvements. I would be interested in knowing if anyone has any comments, and also should such code be implemented in g++ if boost would be willing to add the compiler-specific extra information to mark any classes with efficent swap as such. Note: I am aware there are various ways of trying to approximate if someone has specialised swap, such as checking for a swap member function. However at least at first, it is my belief such a library should probably be strictly op-in. Thank you, Chris

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boost v 1.33 ?
by Robert Ramey 04 Feb '05

04 Feb '05

Could we consider fixing a date for boost 1.33. I would like to agree to just concentrate on fixes, tests and resolving pending issues regarding code currently checked into cvs.. I think this would be relatively painless - at least compared to the last time. Robert Ramey

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[serialization] add_facet question
by Jonathan Turkanis 04 Feb '05

04 Feb '05

Hi Robert, I'd like to use add_facet from serialization in the iostreams library, but I don't understand why the generated locale is dynamically allocated. It would seem be more reusable to declare it as follows: template<typename Facet> inline std::locale add_facet(const std::locale& loc, Facet* facet); If you need a dynamically allocated locale, you could write new std::locale(add_facet(loc, facet)) Jonathan

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Re: [boost] Re: Two alined_storage classes in the CVS
by JOAQUIN LOPEZ MU?Z 04 Feb '05

04 Feb '05

----- Mensaje original ----- De: Robert Ramey <ramey(a)rrsd.com> Fecha: Jueves, Febrero 3, 2005 9:51 pm Asunto: [boost] Re: Two alined_storage classes in the CVS > Since these are in different namespaces, can this not be just > ignored? Is > it worth spending any time on? > Hi Robert, I'm afraid both classes live directly in namespace boost. Joaquín M López Muñoz Telefónica, Investigación y Desarollo

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Gauging Interest: New Functional Library and Programming Language
by christopher diggins 03 Feb '05

03 Feb '05

I have just completed a prototype for a functional programming language called Unimperative, which is also valid C++. This language is implemented in C++ by overloading the comma operator and use of the boost::any library. The language syntax is similar to Scheme but with the significant difference that a Function is called as (MyFxn, x, y). For instance where in Scheme you might write a factorial function as: (define factorial (lambda (n) (if (zero? n) 1 (* n (fact (- n 1)))))) In Unimperative you could write it as: Function Factorial = (If, (Eq, _1, 0), 1, (Mult, _1, (Eval, self, (Dec, _1)))); You can also write procedural code in Unimperative Function F = (Proc, (Output, 1), (Output, 2), (Output, 3), End); I have written a bit more on the language and provided some code examples at http://lambda-the-ultimate.org/node/view/512 . Well anyway, my question to the group, is whether there is some potential interest in this kind of library, and to find out if anyone wants to collaborate. Also, any suggestions on the kinds of features that would make this language/library more interesting to users and/or the boost community? Thanks in advance. Christopher Diggins Object Oriented Template Library (OOTL) http://www.ootl.org

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boost::basic_wrap_stringstream SIGBBUS with SunPRO
by Caleb Epstein 03 Feb '05

03 Feb '05

I'm running into numerous examples of the regression test programs hanging/crashing today due to what may be a problem with basic_wrap_stringstream. Here's an example: /home/nbde52d/src/boost-regression/results/bin/boost/libs/assign/test/my_vector_example.test/sunpro-5_3/debug/my_vector_example --log_level=all Running 1 test case... Entering test suite "List Test Suite" Entering test case "check_list_inserter" ../libs/assign/test/my_vector_example.cpp(98): info: test vec.size() == 10u passed. Exception in "check_list_inserter": signal: memory access violation /home/nbde52d/src/boost-regression/boost/boost/test/impl/unit_test_suite.ipp(179): fatal error in "check_list_inserter": Testing aborted Leaving test case "check_list_inserter" Leaving test suite "List Test Suite" *** errors detected in test suite "List Test Suite"; see standard output for details Here's a stack trace from dbx (same program): (/opt/SUNWspro/bin/../WS6U2/bin/sparcv9/dbx) run Running: my_vector_example (process id 10116) Running 1 test case... signal SEGV (no mapping at the fault address) in _free_unlocked at 0x7fa42bbc 0x7fa42bbc: _free_unlocked+0x0040: ld [%i0 - 0x8], %o0 Current function is boost::test_tools::predicate_result::~predicate_result 47 ~predicate_result() { delete m_message; } (/opt/SUNWspro/bin/../WS6U2/bin/sparcv9/dbx) where [1] _free_unlocked(0x2000, 0x7fabc008, 0x2000, 0x7fabc008, 0x22310, 0x7fa42b64 ), at 0x7fa42bbc [2] free(0x2000, 0x5, 0x5, 0x7fabc008, 0x22310, 0x7fa42b64), at 0x7fa42b6c [3] operator delete(0x2000, 0x7fabc008, 0x0, 0x7fabc008, 0x22310, 0x7fa42b64), at 0x7fb46260 [4] std::basic_stringbuf<char,std::char_traits<char>,std::allocator<char> >::~ basic_stringbuf(0xffbedb60, 0xffbed7b0, 0x34a68, 0x2, 0x222e8, 0x7fb46260), at 0 x71630 [5] std::basic_ostringstream<char,std::char_traits<char>,std::allocator<char> >::~basic_ostringstream(0xffbedb58, 0xffffffff, 0x60, 0xa1768, 0x220b8, 0x4d774) , at 0x66450 [6] boost::basic_wrap_stringstream<char>::~basic_wrap_stringstream(0xffbedb58, 0xa0034, 0xa11bc, 0xffbed838, 0x2f8, 0xa1490), at 0x38250 =>[7] boost::test_tools::predicate_result::~predicate_result(this = 0xffbed88c), line 47 in "predicate_result.hpp" [8] check_list_inserter(), line 98 in "my_vector_example.cpp" [9] boost::unit_test::function_test_case::do_run(this = 0xab248), line 138 in "unit_test_suite.hpp" [10] boost::unit_test::ut_detail::unit_test_monitor::function(this = 0xa0a10), line 79 in "unit_test_monitor.ipp" [11] boost::execution_monitor::run_function(this = 0xa0a10), line 197 in "exec ution_monitor.ipp" [12] boost::detail::catch_signals(exmon = CLASS, catch_system_errors = true, t imeout = 0), line 418 in "execution_monitor.ipp" [13] boost::execution_monitor::execute(this = 0xa0a10, catch_system_errors = t rue, timeout = 0), line 223 in "execution_monitor.ipp" [14] boost::unit_test::ut_detail::unit_test_monitor::execute_and_translate(thi s = 0xa0a10, target_test_case = 0xab248, f = 0xffbee024, timeout = 0), line 46 i n "unit_test_monitor.ipp" [15] boost::unit_test::test_case::run(this = 0xab248), line 173 in "unit_test_ suite.ipp" [16] boost::unit_test::test_suite::do_run(this = 0xab168), line 277 in "unit_t est_suite.ipp" [17] boost::unit_test::test_case::run(this = 0xab168), line 186 in "unit_test_ suite.ipp" [18] main(argc = 1, argv = 0xffbee4dc), line 84 in "unit_test_main.ipp" -- Caleb Epstein caleb dot epstein at gmail dot com

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BIL and boost::any
by christopher diggins 03 Feb '05

03 Feb '05

Hello all, I just realized that an empty BIL interface, BOOST_IDL_BEGIN(IAnything) BOOST_IDL_EMPTY(IAnything) has some common ground with: boost::any Where boost::any stores a copy of a value of practical any type for later extraction, IAnything can point to just about anything. void BoostAnyTest() { int x = 5; boost::any a = x; TEST(any_cast<int>(a) == 5); } void AnythingTest() { int x = 5; IAnything a = x; TEST(extract<int>(a) == 5); } void ObjectTests() { BoostAnyTest(); AnythingTest(); } I just thought this could lead to some kind of connection between the libraries. It might be nice to see this in the boost::any namespace, i.e. a boost::any::any_ref. Christopher Diggins Object Oriented Template Library (OOTL) http://www.ootl.org

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is_incrementable fixes for VC6
by Jonathan Turkanis 03 Feb '05

03 Feb '05

Hi, I've encountered some compile errors using is_incrementable with VC6. They can be fixed by fully qualifying remove_cv and by using macros from type traits to define the traits is_incrementable and is_postfix_incrementable: # include <boost/type_traits/detail/bool_trait_def.hpp> .... // Local macro, #undef'd below # define BOOST_DETAIL_BOOL_TRAIT_DEF1(trait,T,C) \ template< typename T > struct trait \ BOOST_TT_AUX_BOOL_C_BASE(C) \ { \ BOOST_TT_AUX_BOOL_TRAIT_VALUE_DECL(C) \ }; \ /**/ BOOST_DETAIL_BOOL_TRAIT_DEF1(is_incrementable, T, ::boost::detail::is_incrementable_::impl<T>::value) BOOST_DETAIL_BOOL_TRAIT_DEF1(is_postfix_incrementable, T, ::boost::detail::is_incrementable_::postfix_impl<T>::value) # undef BOOST_DETAIL_BOOL_TRAIT_DEF1 Can I go ahead and add this stuff? Also, should I put in lambda and template arity support? Other options would be: * add a header detail/bool_trait_def.hpp for defining traits in namespace detail. * write a macro for generating traits like is_incrementable Jonathan

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