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Re: [Boost-users] circular_buffer, debug and invalid iterator checking
by Jan Gaspar 09 Nov '10

09 Nov '10

Hi Antony, If you a problem only with iterator invalidation (which works in debug mode only) you can disable it completely. The documentation says: The debug support is enabled only in the debug mode (when the NDEBUG is not defined). It can also be explicitly disabled (only for circular_buffer) by defining BOOST_CB_DISABLE_DEBUG macro. Regards, Jan On 6 Nov 2010, at 01:17, Anthony Foglia <afoglia(a)princeton.com> wrote: The invalid iterator checking in the circular_buffer library is excessively strict. It checks not when an iterator is dereferenced, but whenever any operator involving that iterator is used. I have an class defined to keep the last few data points, up to either a maximum number, or some condition on the stored data (e.g. the sum must be below a threshold) is met. So I figured I'd store the data in a circular buffer, and push new data onto the front, and store my own iterator into it to use as the end. If my end iterator is pointing to the next to last element in the buffer, when a new item is pushed onto the front of the circular buffer, that iterator becomes invalid. But that's not a problem for me, because I don't read past it. _Except_ the validity of the iterator is checked even when using it in operator== (and other iterator comparison operators), so my lopp condition tests now throw because the end of my ranges are no longer valid. Why isn't iterator invalidation only checked on dereferencing? Is there any suggested convention for changing my code to work under debug? I would try checking for BOOST_CB_ENABLE_DEBUG and catching these cases before the push_front occurs, but that macro is undefined at the end of the header. Or I could try something more complicated without the macro check, such as storing my ends in reverse iterators, and converting them whenever I need to do comparisons, though that is rather painful. I've attached a simple example which demonstrates the problem, not that it fails when the distance from my_end to end and the next element is pushed into the front. -- Anthony Foglia Princeton Consultants (609) 987-8787 x233 <circular_buffer_test.cpp> _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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[Proto] First steps
by Luc Danton 09 Nov '10

09 Nov '10

Hello everyone, I've been meaning to learn to use Boost.Proto for quite some time and I've finally started getting my hands dirty in code ever since that fantastic video from BoostCon 2010. After the usual exercises that are presented in it and the docs, I've set up my own goal of trying to write composable futures (something that I think quite a lot of people have been doing in their own time). You can see the code at http://pastebin.com/DW4LckMP and I'd welcome comments on what I've been doing wrong and how I could improve the design. I also welcome answers to my following questions: * regarding copying, the docs present the following example: auto sum = boost::proto::lit(1) + 2; here, since the 1 is held by a reference which will outlive (in the variable sum) the actual literal expression (in the call to proto::lit) we will have UB. To avoid this exact problem, and since Boost.Proto is not move aware and std::future is move-only, my terminals are actually of the form: future_expresion<typename boost::proto::terminal<std::future&>::type> (where future_expression is the expression wrapper). Can I do this? Obviously I still have a problem if I do: std::future<int> fint = ... auto sum = ns::compose(fint) + 3; // then use sum.get() don't I? I can't solve it by using proto::deep_copy since std::future is move-only (apparently my terminals get stripped of their reference). This means that the 'correct' way of doing the above would be std::future<int> fint = ... auto const operand = 3; auto sum = ns::compose(fint) + operand; // use sum.get() thus separating lifetimes from computations (expression trees, really). * the following doesn't compile: struct local { int method() { return 1; } int method() const { return 2; } }; auto method = (int (local::*)()) &local::method; auto cmethod = (int (local::*)() const) &local::method; auto f1 = std::async([] { return local(); }); auto f2 = std::async([] { return local(); }); auto r1 = (ns::compose(f1)->*cmethod)(); // this line OK auto r2 = (ns::compose(f2)->*method)(); // Not OK! assert( r1.get() == 2 && r2.get() == 1 ); ( you can replace the above in main() instead of the previous ) Apparently the problem is an attempt to convert a pointer to const local to a pointer to non-const local. Invoking cmethod instead (with the appropriate assertion) is fine. I've checked that the result of ns::compose(f1).get() is indeed a local and not a const local via static_assert. This is using Boost 1.42. Any idea?

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segfault using boost test
by David M. Lee 09 Nov '10

09 Nov '10

I'm consistently getting segfaults trying to use boost test on my Mac. The test works fine on Linux. This is Mac is running Snow Leopard. I compiled boost using Homebrew (http://mxcl.github.com/homebrew/; seehttps://github.com/mxcl/homebrew/blob/master/Library/Formula/boost.rb for the build formula), but I've also tried building Boost myself with the same results. Any help figuring this out would be greatly appreciated! Here's the test I'm running: #define BOOST_TEST_MODULE simple #include <boost/test/included/unit_test.hpp> BOOST_AUTO_TEST_CASE(testSimple) { BOOST_CHECK_EQUAL(true, true); } Here's the backtrace: Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_INVALID_ADDRESS at address: 0x0000000000000000 0x0000000100265ccc in boost::unit_test::framework::get () (gdb) bt #0 0x0000000100265ccc in boost::unit_test::framework::get () #1 0x0000000100270855 in boost::unit_test::results_collector_t::assertion_result () #2 0x00000001000242cf in boost::unit_test::framework::assertion_result () #3 0x00000001000262a6 in boost::test_tools::tt_detail::check_impl () #4 0x000000010006aa01 in boost::test_tools::tt_detail::check_frwd<boost::test_tools::tt_detail::equal_impl_frwd, bool, bool> () #5 0x0000000100026409 in testSimple::test_method () #6 0x0000000100026468 in testSimple_invoker () #7 0x000000010004056d in boost::unit_test::ut_detail::invoker<boost::unit_test::ut_detail::unused>::invoke<void (*)()> () #8 0x0000000100040591 in boost::unit_test::ut_detail::callback0_impl_t<boost::unit_test::ut_detail::unused, void (*)()>::invoke () #9 0x000000010005bf38 in boost::unit_test::callback0<boost::unit_test::ut_detail::unused>::operator() () #10 0x0000000100014698 in boost::unit_test::(anonymous namespace)::zero_return_wrapper_t<boost::unit_test::callback0<boost::unit_test::ut_detail::unused> >::operator() () #11 0x00000001000146b9 in boost::unit_test::ut_detail::invoker<int>::invoke<boost::unit_test::(anonymous namespace)::zero_return_wrapper_t<boost::unit_test::callback0<boost::unit_test::ut_detail::unused> > > () #12 0x00000001000146d9 in boost::unit_test::ut_detail::callback0_impl_t<int, boost::unit_test::(anonymous namespace)::zero_return_wrapper_t<boost::unit_test::callback0<boost::unit_test::ut_detail::unused> > >::invoke () #13 0x000000010005c65c in boost::unit_test::callback0<int>::operator() () #14 0x000000010005c6a7 in boost::detail::do_invoke<boost::scoped_ptr<boost::detail::translate_exception_base>, boost::unit_test::callback0<int> > () #15 0x00000001000206f1 in boost::execution_monitor::catch_signals () #16 0x00000001000218da in boost::execution_monitor::execute () #17 0x00000001000240a0 in boost::unit_test::unit_test_monitor_t::execute_and_translate () #18 0x000000010006b78d in boost::unit_test::framework_impl::visit () #19 0x0000000100008b2e in boost::unit_test::traverse_test_tree () #20 0x0000000100023753 in boost::unit_test::traverse_test_tree () #21 0x00000001000233a8 in boost::unit_test::traverse_test_tree () #22 0x000000010002376a in boost::unit_test::traverse_test_tree () #23 0x000000010002aad6 in boost::unit_test::framework::run () #24 0x000000010002ae39 in boost::unit_test::unit_test_main () #25 0x000000010002b0c2 in main () Thanks! dave <>< -- David M. Lee Digium, Inc. | Software Developer 445 Jan Davis Drive NW - Huntsville, AL 35806 - USA Check us out at: www.digium.com & www.asterisk.org

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[Boost 1.44][BGL] Compiling error with MinGW
by Florian.PONROY＠fr.thalesgroup.com 09 Nov '10

09 Nov '10

Hi folks, My C++ Windows/Linux project used to compile properly using the following items: * Boost 1.33.1, using BGL, Serialization, Thread ; * GNU g++ 4.1.2 under Linux ; * MinGW 3.4.5 under Linux (cross-compiling). I recently updated my Boost distribution to version 1.44. Unfortunately, I now have the following BGL/linking error compiling with MinGW : /path/to/liblocd_topology_manager.a(locTopology.o):locTopology.cpp:(.rdata$_ ZZN5boost3putINS_26vec_adj_list_vertex_id_mapINS_8propertyINS_13vertex_root_ tEiNS_11no_propertyEEEjEEEEvRKNS_17two_bit_color_mapIT_EENS_15property_trait sIS8_E8key_typeENS_18two_bit_color_typeEE17elements_per_char+0x0): multiple definition of `_elements_per_char' /path/to/liblocd_topology_manager.a(locTopology.o):locTopology.cpp:(.rdata$_ ZZN5boost3putINS_26vec_adj_list_vertex_id_mapINS_8propertyINS_13vertex_root_ tEiNS_11no_propertyEEEjEEEEvRKNS_17two_bit_color_mapIT_EENS_15property_trait sIS8_E8key_typeENS_18two_bit_color_typeEE17elements_per_char+0x0): first defined here I've checked the //www.boost.org/doc/libs/1_44_0/libs/graph/doc/trouble_shooting.html webpage, but I haven't seen any answer related to my problem. For sure, the MinGW compiler version we use is pretty old. Since updating it would be very cumbersome in our case, I would like to be sure it's actually a compiler issue. Thanks in advance for your advice. Best regards, -- Florian PONROY Thales Land & Joint France Tel. : +33(0)1 41 304 363 Fax : +33(0)1 41 303 907 Email : florian.ponroy(a)fr.thalesgroup.com

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FW: Build boost win MinGW ?
by krys＠polarlights.net 09 Nov '10

09 Nov '10

Hi, I'm trying to use Boost 1.44 with QT Creator for this I have try this : 1 - download boost 1.44 from the Boost web site, and unzip it 2 - download the bjam.exe and copy it in the root of boost 3 - run the following command : d:\Boost\boost_1_44_0>bjam stage --build-type=complete --build-dir="d:\Boost144\ build" --toolset=gcc --stagedir="d:\Boost144" But I got the following errors : d:\Boost\boost_1_44_0>bjam stage --build-type=complete --build-dir="d:\Boost144\ build" --toolset=gcc --stagedir="d:\Boost144" notice: could not find main target stage notice: assuming it is a name of file to create. D:/Boost/boost_1_44_0/tools/build/v2/build\project.jam:737: in attribute warning: rulename $($(project).attributes).get expands to empty string D:/Boost/boost_1_44_0/tools/build/v2/build\project.jam:749: in project.target D:/Boost/boost_1_44_0/tools/build/v2\build-system.jam:707: in load d:\Boost\boost_1_44_0\tools\build\v2/kernel\modules.jam:283: in import d:\Boost\boost_1_44_0\tools\build\v2\kernel\bootst rap.jam:142: in boost-build d:\Boost\boost_1_44_0\boost-build.jam:17: in module scope D:/Boost/boost_1_44_0/tools/build/v2/build\project.jam:737: in project.attribute warning: rulename $($(project).attributes).get expands to empty string D:/Boost/boost_1_44_0/tools/build/v2/build\targets.jam:206: in object(project-ta rget)(a)43.__init__ D:/Boost/boost_1_44_0/tools/build/v2/kernel\class.jam:88: in new D:/Boost/boost_1_44_0/tools/build/v2/build\project.jam:749: in project.target D:/Boost/boost_1_44_0/tools/build/v2\build-system.jam:707: in load d:\Boost\boost_1_44_0\tools\build\v2/kernel\modules.jam:283: in import d:\Boost\boost_1_44_0\tools\build\v2\kernel\bootst rap.jam:142: in boost-build d:\Boost\boost_1_44_0\boost-build.jam:17: in module scope :/Boost/boost_1_44_0/tools/build/v2/build\project.jam:737: in project.attribute warning: rulename $($(project).attributes).get expands to empty string D:/Boost/boost_1_44_0/tools/build/v2/build\targets.jam:226: in object(project-ta rget)(a)43.get D:/Boost/boost_1_44_0/tools/build/v2\build-system.jam:720: in load d:\Boost\boost_1_44_0\tools\build\v2/kernel\modules.jam:283: in import d:\Boost\boost_1_44_0\tools\build\v2\kernel\bootst rap.jam:142: in boost-build d:\Boost\boost_1_44_0\boost-build.jam:17: in module scope D:/Boost/boost_1_44_0/tools/build/v2\build-system.jam:721: in load *** argument error * rule project.load ( jamfile-location ) * called with: ( ) * missing argument jamfile-location D:/Boost/boost_1_44_0/tools/build/v2/build\project.jam:53:see definition of rule 'load' being called d:\Boost\boost_1_44_0\tools\build\v2/kernel\modules.jam:283: in import d:\Boost\boost_1_44_0\tools\build\v2\kernel\bootst rap.jam:142: in boost-build d:\Boost\boost_1_44_0\boost-build.jam:17: in module scope Do you have an idea to solve my problem and build boost please ? Thx

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[Fusion] functor fused and unfused at the same time
by alfC 09 Nov '10

09 Nov '10

Hi, I have an internally generated templated functor that naturally takes fusion sequences. since this function can also be called by the user I want to make it also "unfused" For example, the struct is struct F{ typedef result_of::make_map::type mapped_arguments; template<class Args> struct result{ typedef double type; }; double operator()(mapped_arguments const& args) const{ return at_key(args) + at_key<q>(args); } }; and can be called as F f; f(make_map<p,q>(one, two)); (I need this because of internal conventions of the library) but I want it to be also called as f(one, two); // somehow (I need this because the user can call it) I tried this struct F : unfused<F const&>{ typedef result_of::make_map::type mapped_arguments; template<class Args> struct result{ typedef double type; }; double operator()(mapped_arguments const& args) const{ return at_key(args) + at_key<q>(args); } }; but I get: usr/include/boost/utility/result_of.hpp:80: error: invalid use of incomplete type ‘const struct F’ I then tried this struct F_impl{ typedef result_of::make_map::type mapped_arguments; template<class Args> struct result{ typedef double type; }; double operator()(mapped_arguments const& args) const{ return at_key(args) + at_key<q>(args); } }; struct F : F_impl, unfused<F_impl const&>{ F() : unfused<F_impl const&>((F_impl const&)*this){} F(F_impl const& f) : F_impl(f), unfused<F_impl const&>((F_impl const&)*this){} template<class Args> struct result{ typedef typename F_impl::result<Args>::type type; }; using F_impl::operator(); }; which seems to work but looks and feels awkward. It works in the sense that F f; can be called clog << f(make_map<p,q>(1.,2.)) << endl; clog << fu(uno, dos) << endl; Is there any simpler way to get this. Thank you, Alfredo

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[asio] __sync_lock_test_and_set problem, cross-compiling for ARM
by Igor R 09 Nov '10

09 Nov '10

Hello, I'm trying to cross-compile my project for Android (Win, cygwin, crystax-ndk). The linker emits the following error: ../asio/detail/gcc_fenced_block.hpp:41: undefined reference to `__sync_lock_test_and_set_4' I understand that in 1.44 I can disable this "fenced-block" by defining BOOST_ASIO_DISABLE_FENCED_BLOCK, but I'm not sure it's safe to do this. IUUC, __sync_lock_test_and_set gcc function is unavailable for some older arm-based platforms, but should be available for the newer ones, shouldn't it? So maybe I have to define some compiler flag to enable it? I'd appreciate any idea. Thanks.

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[fusion][Functional] LValue arguments limitation
by alfC 09 Nov '10

09 Nov '10

Fusion manual says: Only LValue arguments are accepted. To overcome this limitation, apply Boost.Functional/Forward. I understand that this has to do with not being able to pass literal constants to the function, e.g. unfused<f> uf; uf(1., 2.); //can't First: 1) can anybody explain why is this? 2) uf( (double const&) 1., (double const&) 2. ); seems to work, but it is probably a hack. (not portable maybe?) 3) the manual says also to use Boost.Functional/Forward to overcome this limitation. What does it mean by this? Thank you, Alfredo

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unable to load the module from simple example
by Cuma Tyszkiewicz 09 Nov '10

09 Nov '10

Hello I have followed the simple example from the python boost wiki page: my source file py_moddef.cc: ___________________________________________ #include <string> #include <boost/python.hpp> char const* greet() { return "hello, world"; } BOOST_PYTHON_MODULE(hello_ext) { using namespace boost::python; def("greet", greet); } ____________________________________________ In the next step I have built the shared library 1. g++ -c -fpic -I/usr/include/python2.6/ py_moddef.cc 2. ld -G py_moddef.o -o libpy_moddef.so The libpy_moddef.so file I have copied to the directory which next was included to PYTHONPATH >>> import sys >>> sys.path.append("the_path") I am not able to import the module "hello_ext" defined in py_moddef.cc, but I am able to import each other python module from this path, so something wrong is with the shared library. >>> import hello_ext ImportError: No module named hello_ext Please explain to me what is wrong. I will be gratefull for any help. Best regards Cuma

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[xpressive] Using it with input iterators or how far the backtracing will go back
by Alex Dubov 09 Nov '10

09 Nov '10

Greetings. There exists a fairly common need to apply regexp matching to streams, rather than to blocks of data. Streams are represented by input iterators, which have no ability to decrement their value. On the other hand, xpressive requires a bidirectional iterator, to go back and forth as required by backtracking (if I understand correctly). One approach to work around this limitation is to create an iterator adapter, which will store a copy of every character delivered by input iterator and provide expressive with bidi iterator to work with. So the question is, how can one establish the size for this iterator adapter's internal storage so as to avoid match failures due to incomplete storage and avoid storing too much unnecessary data? I suppose, the storage can be reset when the match is reported. This, however, still leaves an open problem for situations where matches are separated by, possibly, gigabytes of non-matching data. Alternatively, may there be a way to relax the iterator requirements of the xpressive library itself? If xpressive could be made to store partial match data within its data structures, bidi iterators would not be strictly necessary. Thanks.

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