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[iostreams] Why devices must be copy-constructible?
by Alberto Ganesh Barbati 07 Nov '05

07 Nov '05

Hi, I started using the iostreams library for a pet project. I thinks it's a great piece of software. However, I immediately stumbled in what I think it may be a defect. Consider this simple source device: #include <boost/iostreams/stream.hpp> struct Source : boost::noncopyable { typedef char char_type; typedef boost::iostreams::source_tag category; Source(int); // ctor std::streamsize read(char* s, std::streamsize n) { // implementation here } private: /* ... private members here */ }; int main() { boost::iostreams::stream<Source> s(0); } the boost::noncopyable up there has been put because the device keeps handles to OS resources whose duplication can be very expensive. I was amazed that the code above doesn't compile. This is the error message reported by VC7.1: C:\lib\Boost\include\boost-1_33\boost\iostreams\detail\wrap_unwrap.hpp(52) : error C2558: struct 'Source' : no copy constructor available or copy constructor is declared 'explicit' (full error message is very long and is reported, for reference, at the end of the message) It seems that a device must be copy-constructibile. In particular, the code above makes at least three short-lived copies of the device. Question is: why? I believe this requirement is unintended and not due to a conscious design choice, my arguments are: 1) it's not documented, there is no mention of such requirement in http://www.boost.org/libs/iostreams/doc/concepts/device.html 2) it's unnatural and I believe my case (where copying the device could be expensive) occurs more often in practice than the opposite case 3) from the error messages it seems that a copy is only required as a side-effect of the template machinery used in BOOST_IOSTREAMS_FORWARD. In fact, the offending line detail\wrap_unwrap.hpp(52) is: inline T wrap(const T& t BOOST_IOSTREAMS_DISABLE_IF_STREAM(T)) { return t; } that requires T to be copy-constructible. Am I missing something? Thanks in advance, Ganesh ----- full error messaage follows C:\lib\Boost\include\boost-1_33\boost\iostreams\detail\wrap_unwrap.hpp(52) : error C2558: struct 'Source' : no copy constructor available or copy constructor is declared 'explicit' C:\lib\Boost\include\boost-1_33\boost\iostreams\stream_buffer.hpp(90) : see reference to function template instantiation 'T boost::iostreams::detail::wrap<T>(const T &,boost::disable_if_c<B,void>::type *)' being compiled with [ T=Source, B=false ] C:\lib\Boost\include\boost-1_33\boost\iostreams\stream_buffer.hpp(90) : while compiling class-template member function 'void boost::iostreams::stream_buffer<T,Tr,Alloc>::open(const T &,int,int)' with [ T=Source, Tr=std::char_traits<char>, Alloc=std::allocator<char> ] C:\lib\Boost\include\boost-1_33\boost\utility\base_from_member.hpp(69) : see reference to class template instantiation 'boost::iostreams::stream_buffer<T,Tr,Alloc>' being compiled with [ T=Source, Tr=std::char_traits<char>, Alloc=std::allocator<char> ] C:\lib\Boost\include\boost-1_33\boost\iostreams\stream.hpp(61) : see reference to class template instantiation 'boost::base_from_member<MemberType>' being compiled with [ MemberType=boost::iostreams::stream_buffer<Source,std::char_traits<char>,std::allocator<char>> ] C:\lib\Boost\include\boost-1_33\boost\iostreams\stream.hpp(98) : see reference to class template instantiation 'boost::iostreams::detail::stream_base<Device,Tr,Alloc>' being compiled with [ Device=Source, Tr=std::char_traits<char>, Alloc=std::allocator<char> ] TestVc2.cpp(26) : see reference to class template instantiation 'boost::iostreams::stream<Device>' being compiled with [ Device=Source ]

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bjam question
by Robert Ramey 07 Nov '05

07 Nov '05

I have made some tests to compare serialization of different types of data different archives and to compare against raw i/o. So far so good. Now I would like to alter my test/Jamfile to achieve the following: a) I would like to run a command after the test run to display the size of the test executable. b) I would like to run a command (gprof) after the test for certain tests. I would hope that the output of these post processing command would appear in the output log of the standard output. c) I would like to inhibit the running of these tests when the build is in debug mode. d) I intend to uses these in my own environment as this would impose extra burden on testing and I don't really need to run this stuff except for once in a while. However, I'm am curious how one achieves the effect of the config_info test on the main test matrix whereby the test passes but still produces a link to the test output. Robert Ramey

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Re: [boost] Global object initialization [was: Phoenix-2 prerelease]
by David Abrahams 07 Nov '05

07 Nov '05

Joel de Guzman <joel(a)boost-consulting.com> writes: > Any links to the thread? No, we've been doing this offline. I'll try to forward something to you. >> 1. The placeholders are statically initialized const POD objects in >> an unnamed namespace and you have likely ODR violation when used >> by templates in multiple translation units. >> 2. The placeholders are dynamically initialized references in an >> unnamed namespace and you risk undefined behavior when they are >> used without initialization due to initialization order issues >> 3. The placeholders are dynamically initialized objects in an >> unnamed >> namespace, and you have likely ODR violation *and* initialization >> order issues >> Seems from the doc like you have #3, which is the worst of both >> worlds. No? > > Actually it is 4: > > 4. The placeholders are dynamically initialized *const* objects in > namespace phoenix That's essentially 1, in that you get a different object in each TU and are likely to end up with an ODR violation. > Well, we can easilly make them PODs, so: > > 5. The placeholders are statically initialized *const* POD objects > in namespace phoenix Same problem. > So, question: how does this code below constitute ODR violation? > > namespace x // named > { > T const pod = T(); // T is a POD > } It does not. You need two translation units and a template, instantiated in each one, that uses your object "pod." > is this link relevant?: > http://lists.boost.org/Archives/boost/2004/06/67159.php Precisely. > how about: > http://lists.boost.org/Archives/boost/2001/05/12609.php I don't think so. Internal linkage doesn't save you from an ODR violation. -- Dave Abrahams Boost Consulting www.boost-consulting.com

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Re: [boost] Gender neutral documentation
by brangdon＠cix.compulink.co.uk 07 Nov '05

07 Nov '05

In-Reply-To: <uacgkh76q.fsf(a)boost-consulting.com> dave(a)boost-consulting.com (David Abrahams) wrote (abridged): > Angus' version is better. > > This means that if Bind is unneeded the user can discard it > completely. > > Of course, "this" needs an antecedent :) > > > For example, if Bind is unneeded the user can discard it > completely. > > is much more to the point. But "is unneeded" again fails to say who doesn't need it, and hence fails to say why it isn't needed. It's vague. I think clarity and precision are more important than good grammar or political correctness. -- Dave Harris, Nottingham, UK.

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[test] --catch_system_errors=no doesn't work with minimal test
by David Abrahams 07 Nov '05

07 Nov '05

When using boost/test/minimal.hpp, it doesn't respond to the presence of --catch_system_errors=no, which makes it unreasonably difficult to debug problems on Windows. All I get is an exception caught by the test library, with all of the info about the real cause of the error lost, which is absolutely unhelpful. It seems to me that the minimal configuration ought to at least be useful for writing and debugging simple test cases. -- Dave Abrahams Boost Consulting www.boost-consulting.com

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[mpl] apply as a placeholder expression?
by Eric Niebler 07 Nov '05

07 Nov '05

I have an MPL sequence of metafunction classes. I want to apply<> each with mpl::transform. So I did this: struct metafnclass { template<typename T> struct apply { typedef T type; }; }; typedef mpl::vector<metafnclass, metafnclass> metafnclasses; typedef mpl::transform< metafnclasses , mpl::apply<mpl::_1, int> >::type transmetafnclasses; This fails horribly, and I don't know why. If I add an indirection like this: template<typename T,typename U> struct indirect_apply : mpl::apply<T, U> {}; typedef mpl::transform< metafnclasses , indirect_apply<mpl::_1, int> >::type transmetafnclasses; then it works fine. Why should that be? Is something getting evaluated too eagerly? -- Eric Niebler Boost Consulting www.boost-consulting.com

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multi_index problem in VC 7.1
by Brock Peabody 07 Nov '05

07 Nov '05

If I try to compile the very first example in multi index I get the following error: c:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\boost\multi_index\detail\node_type.hpp(56) : error C2903: 'node_class' : symbol is neither a class template nor a function template I get this with 1.33 and 1.32. I've tried many different compiler options. Here is my latest command line: /Ox /D "WIN32" /D "NDEBUG" /D "_CONSOLE" /D "NOMINMAX" /D "_AFXDLL" /D "_MBCS" /FD /EHsc /MD /GS /Fo"Release/" /Fd"Release/vc70.pdb" /W3 /nologo /c /Wp64 /Zi /TP I've dug around a bit and I can't make any sense of this problem. Has anyone else seen this? The exact code I'm compiling is: #include <boost/multi_index/key_extractors.hpp> #include <boost/multi_index_container.hpp> #include <string> struct employee { int id; std::string name; employee(int id,const std::string& name):id(id),name(name){} bool operator<(const employee& e)const{return id<e.id;} }; using namespace boost::multi_index; // define a multiply indexed set with indices by id and name typedef multi_index_container< employee, indexed_by< // sort by employee::operator< ordered_unique<identity<employee> >, // sort by less<string> on name ordered_non_unique<member<employee,std::string,&employee::name> > > > employee_set; employee_set e; Thanks!

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Boost regression notification (2005-11-07 [RC_1_33_0])
by Douglas Gregor 07 Nov '05

07 Nov '05

Boost regression test failures ------------------------------ Report time: 2005-11-07T14:04:14Z This report lists all regression test failures on release platforms. Detailed report: http://engineering.meta-comm.com/boost-regression/CVS-RC_1_33_0/developer/i… 2 failures in 2 libraries: program_options (1) python (1) |program_options| variable_map_test: vc-8_0 |python| map_indexing_suite: vc-8_0

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Boost regression notification (2005-11-07 [HEAD])
by Douglas Gregor 07 Nov '05

07 Nov '05

Boost regression test failures ------------------------------ Report time: 2005-11-07T06:00:45Z This report lists all regression test failures on release platforms. WARNING: The following libraries have failing regression tests but do not have a maintainer on file. Once a maintainer is found, add an entry to libs/maintainers.txt to eliminate this message. io Detailed report: http://engineering.meta-comm.com/boost-regression/CVS-HEAD/developer/issues… 202 failures in 12 libraries: bind (1) concept_check (11) graph (2) io (1) mpl (1) serialization (30) spirit (8) thread (4) tr1 (120) tuple (1) typeof (18) xpressive (5) |bind| bind_dm3_test: intel-win32-9_0 |concept_check| stl_concept_covering: cw-9_4 gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3.4.4-linux gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin intel-win32-9_0 intel-win32-9_0 vc-7_1 |graph| graphviz_test: vc-7_1 layout_test: intel-win32-9_0 |io| ios_state_unit_test: intel-win32-9_0 |mpl| size_t: gcc-4_0-darwin |serialization| test_class_info_load_binary_archive: gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin test_class_info_load_binary_archive_dll: gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin test_class_info_load_text_archive: gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin test_class_info_load_text_archive_dll: gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin test_class_info_load_text_warchive: gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin test_class_info_load_text_warchive_dll: gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin test_class_info_load_xml_archive: gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin test_class_info_load_xml_archive_dll: gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin test_class_info_load_xml_warchive: gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin test_class_info_load_xml_warchive_dll: gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin |spirit| action_tests_debug: gcc-3_4_3-sunos distinct_tests_debug: gcc-3_4_3-sunos escape_char_parser_tests_debug: gcc-3_4_3-sunos grammar_def_test_debug: gcc-3_4_3-sunos switch_problem_debug: gcc-3_4_3-sunos switch_tests_single_debug: gcc-3_4_3-sunos traverse_tests: intel-win32-9_0 traverse_tests_debug: intel-win32-9_0 |thread| test_condition: gcc-3_4_3-sunos test_mutex: gcc-3_4_3-sunos test_tss: gcc-3_4_3-sunos gcc-3_4_3-sunos |tr1| run_complex_overloads: gcc-2.95.3-linux std_run_complex_overloads: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.4.4-linux std_run_random: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.4.4-linux std_test_array: gcc-2.95.3-linux std_test_bind: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3.4.4-linux gcc-3_3-darwin intel-win32-9_0 std_test_boost: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux std_test_complex: gcc-2.95.3-linux std_test_function: gcc-2.95.3-linux std_test_hash: gcc-2.95.3-linux std_test_mem_fn: gcc-2.95.3-linux std_test_random: gcc-2.95.3-linux std_test_reference_wrapper: gcc-2.95.3-linux std_test_regex: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.4.4-linux std_test_result_of: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux std_test_shared_ptr: gcc-2.95.3-linux std_test_tr1_include: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux std_test_tuple: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux std_test_type_traits: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3_3-darwin test_algorithm: gcc-2.95.3-stlport-4.6.2-linux test_bind: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3.4.4-linux gcc-3_3-darwin intel-win32-9_0 test_complex: gcc-2.95.3-linux test_exception: gcc-2.95.3-stlport-4.6.2-linux test_functional: gcc-2.95.3-linux test_hash: gcc-2.95.3-linux test_memory: gcc-2.95.3-linux test_new: gcc-2.95.3-stlport-4.6.2-linux test_regex: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.4.4-linux test_result_of: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux test_tr1_include: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux test_tuple: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux test_type_traits: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3_3-darwin test_utility: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux tr1_add_const_test: gcc-2.95.3-linux tr1_add_cv_test: gcc-2.95.3-linux tr1_add_pointer_test: gcc-2.95.3-linux tr1_add_reference_test: gcc-2.95.3-linux tr1_add_volatile_test: gcc-2.95.3-linux tr1_aligned_storage_test: gcc-2.95.3-linux tr1_alignment_of_test: gcc-2.95.3-linux tr1_extent_test: gcc-2.95.3-linux tr1_has_nothrow_assign_test: gcc-2.95.3-linux tr1_has_nothrow_constr_test: gcc-2.95.3-linux tr1_has_nothrow_copy_test: gcc-2.95.3-linux tr1_has_trivial_assign_test: gcc-2.95.3-linux tr1_has_trivial_constr_test: gcc-2.95.3-linux tr1_has_trivial_copy_test: gcc-2.95.3-linux tr1_has_trivial_destructor_test: gcc-2.95.3-linux tr1_has_virtual_destructor_test: gcc-2.95.3-linux tr1_is_arithmetic_test: gcc-2.95.3-linux tr1_is_array_test: gcc-2.95.3-linux tr1_is_base_of_test: gcc-2.95.3-linux tr1_is_class_test: gcc-2.95.3-linux tr1_is_compound_test: gcc-2.95.3-linux tr1_is_const_test: gcc-2.95.3-linux tr1_is_empty_test: gcc-2.95.3-linux tr1_is_enum_test: gcc-2.95.3-linux tr1_is_floating_point_test: gcc-2.95.3-linux tr1_is_function_test: gcc-2.95.3-linux tr1_is_fundamental_test: gcc-2.95.3-linux tr1_is_integral_test: gcc-2.95.3-linux tr1_is_member_func_test: gcc-2.95.3-linux tr1_is_member_obj_test: gcc-2.95.3-linux tr1_is_member_pointer_test: gcc-2.95.3-linux tr1_is_object_test: gcc-2.95.3-linux tr1_is_pod_test: gcc-2.95.3-linux tr1_is_pointer_test: gcc-2.95.3-linux tr1_is_polymorphic_test: gcc-2.95.3-linux tr1_is_reference_test: gcc-2.95.3-linux tr1_is_same_test: gcc-2.95.3-linux tr1_is_scalar_test: gcc-2.95.3-linux tr1_is_signed_test: gcc-2.95.3-linux tr1_is_union_test: gcc-2.95.3-linux tr1_is_unsigned_test: gcc-2.95.3-linux tr1_is_void_test: gcc-2.95.3-linux tr1_is_volatile_test: gcc-2.95.3-linux tr1_rank_test: gcc-2.95.3-linux tr1_remove_all_extents_test: gcc-2.95.3-linux tr1_remove_bounds_test: gcc-2.95.3-linux tr1_remove_const_test: gcc-2.95.3-linux tr1_remove_cv_test: gcc-2.95.3-linux tr1_remove_extent_test: gcc-2.95.3-linux tr1_remove_pointer_test: gcc-2.95.3-linux tr1_remove_reference_test: gcc-2.95.3-linux tr1_remove_volatile_test: gcc-2.95.3-linux tr1_tricky_abstract_type_test: gcc-2.95.3-linux tr1_tricky_add_pointer_test: gcc-2.95.3-linux tr1_tricky_incomplete_type_test: gcc-2.95.3-linux tr1_tricky_partial_spec_test: gcc-2.95.3-linux |tuple| tuple_test_bench: gcc-3_4_3-sunos |typeof| data_member_native: cw-9_4 function_native: cw-9_4 function_ptr_native: cw-9_4 function_ref_native: cw-9_4 lvalue_native: cw-9_4 member_function_native: cw-9_4 modifiers_emulation: cw-9_4 modifiers_native: cw-9_4 noncopyable_native: cw-9_4 std_emulation: cw-9_4 std_native: cw-9_4 template_dependent_native: cw-9_4 template_enum_native: cw-9_4 template_int_native: cw-9_4 template_multiword_native: cw-9_4 template_tpl_native: cw-9_4 template_type_native: cw-9_4 type_native: cw-9_4 |xpressive| test3u: gcc-3_3-darwin test4u: gcc-3_3-darwin test5u: gcc-3_3-darwin test6u: gcc-3_3-darwin test9u: gcc-3_3-darwin

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execution_monitor and threads
by Raymond Haeb 07 Nov '05

07 Nov '05

Hi, Is there any defined behavior of the execution_monitor if the controlled function starts new threads? Does every thread need its own monitor or is one for the main thread from where the others are started sufficient? Thanks in advance, Raymond

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