May 2007 - Boost-users - lists.preview.boost.org

[asio] some design questions
by Yuval Ronen 16 Jun '07

16 Jun '07

Hi. I'm looking at the Design page of the asio docs (http://tinyurl.com/2b5afn) and several questions come to mind: 1. The "Proactor" page has Advantages/Disadvantages section, but it doesn't specify in comparison to what (advantages and disadvantages are always compared to something). I'm getting the impression that it's compared to the Reactor approach. Is this correct? 2. The "Platform-Specific Implementation" page notes that when using select/epoll/kqueue, demultiplexing is performed in one of the threads that calls boost::asio::io_service::run(). I assume that when this thread is awaken to perform some task, one of the other threads that called run() on the same boost::asio::io_service takes it position as waiting on select/epoll/kqueue. Is this correct? 3. The "Platform-Specific Implementation" page also notes that "An additional thread per io_service is used to emulate asynchronous host resolution. This thread is created on the first call to either boost::asio::ip::tcp::resolver::async_resolve() or boost::asio::ip::udp::resolver::async_resolve()." So I guess that if I resolve() rather than async_resolve(), then no thread is created, and the actual resolving is done in the thread that called resolve()? I think all these notes would be a good addition to the docs. Thanks.

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Boost 1.34 and Visual C++ "Orcas"
by Josue Gomes 16 Jun '07

16 Jun '07

Hi, I've successfully built Boost 1.34 with MS Visual C++ "Orcas" Express Edition. To do so I've modified msvc.jam and visualc.hpp. Here the patch files for all of you interested. --- msvc.jam 2007-05-13 07:37:48.562500000 -0300 +++ msvc.jam 2007-05-12 13:10:57.734375000 -0300 @@ -231,6 +231,10 @@ local rule configure-really ( { # Even if version is not explicitly specified, try to detect the version # from the path. + if [ MATCH "(Microsoft Visual Studio 9.0)" : $(command) ] + { + version = 9.0 ; + } if [ MATCH "(Microsoft Visual Studio 8)" : $(command) ] { version = 8.0 ; --- visualc.hpp 2006-01-13 04:48:08.000000000 -0200 +++ visualc.hpp 2007-05-12 13:07:19.500000000 -0300 @@ -168,8 +168,8 @@ #error "Compiler not supported or configured - please reconfigure" #endif // -// last known and checked version is 1400 (VC8): -#if (_MSC_VER > 1400) +// last known and checked version is 1500 (VC9): +#if (_MSC_VER > 1500) # if defined(BOOST_ASSERT_CONFIG) # error "Unknown compiler version - please run the configure tests and report the results" # else Regards, josuegomes at gmail dot com

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[mpl] can't transform a map
by Yuval Ronen 12 Jun '07

12 Jun '07

I have the following code: #include <utility> #include <boost/mpl/map.hpp> #include <boost/mpl/transform.hpp> template <typename MplPair> struct make_ptr_pair1 { typedef std::pair<typename MplPair::first *, typename MplPair::second *> type; }; template <typename First, typename Second> struct make_ptr_pair2 { typedef std::pair<First *, Second *> type; }; int main(int argc, char *argv[]) { namespace mpl = boost::mpl; typedef mpl::map< mpl::pair<int, double> > my_map; //typedef mpl::transform< my_map, make_ptr_pair1<mpl::_1> >::type ptr_pair_seq1; //typedef mpl::transform< my_map, make_ptr_pair2<mpl::_1, mpl::_2> >::type ptr_pair_seq2; return 0; } If I uncomment any of the two mpl::transform lines in main(), the code doesn't compile (VC8). The point is to get a sequence of std::pairs out of the content of the mpl::map. Is there anything I'm doing wrong? Can mpl::transform be used for mpl::map? Maybe I can do it with fusion, but the above code seems to be something that's supposed to be working, isn't it? Yuval

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BGL: INTERNAL COMPILER ERROR in VC7.1
by Yariv Tal 10 Jun '07

10 Jun '07

This one was already posted by Nicholas Burlett awhile back (see http://lists.boost.org/MailArchives/boost-users/msg06534.php) but I have some new info that may help. The problem: ========= When compiling code that uses the boost.graph library the VC7.1 compiler shouts: c:\boost_1_32_0\boost\mpl\aux_\preprocessed\plain\apply_wrap.hpp(48) : fatal error C1001: INTERNAL COMPILER ERROR As Nicholas already noted, this seems to be due to some compiler problem with the boost.graph out_edge_iterators since it is caused by the following lines in my code: (FilteredGraphGenerator::FilteredGraph is a typedef of a boost::filtered_graph) typedef boost::graph_traits<FilteredGraphGenerator::FilteredGraph> ::out_edge_iterator oedge_iterator; oedge_iterator edgesItr, edgesEnd; boost::tie(edgesItr, edgesEnd) = boost::out_edges(itr->first, m_g.m_filteredGraph); while (edgesItr != edgesEnd) { // do anything! } In fact, it seems to be related to the operator!= between iterators (if the while loop is commented out it compiles). How ever, the error persists even after changing the operator!= to operator== : while (edgesItr == edgesEnd) { // do anything! } ========================================================================== Some findings: =========== * We used to use boost_1_30_0 and the code used to compile PERFECTLY. The problem only appeared after migrating to boost_1_32_0. * Calling directly to the "equal" function in iterator_core_access instead of the operator== works. typedef boost::graph_traits<FilteredGraphGenerator::FilteredGraph> ::out_edge_iterator oedge_iterator; oedge_iterator edgesItr, edgesEnd; boost::tie(edgesItr, edgesEnd) = boost::out_edges(itr->first,m_g.m_filteredGraph); while (boost::iterator_core_access::equal(edgesItr, edgesEnd, boost::mpl::true_())) { // do somthing } * The error message location is at the mpl::apply_wrap2 function. Any relation to the mpl::apply2 function used for declaring the operator== in the BOOST_ITERATOR_FACADE_INTEROP_HEAD macro? Have these functions changed since v1.30.0?

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[parameter] A few usage questions
by John Maddock 08 Jun '07

08 Jun '07

I have a few usage questions for the Boost.Parameter library: 1) If I want to have a function called "policy" that's declared using BOOST_PARAMETER_FUNCTION can I access the types of the arguments both from within the functions body and for the functions return type: BOOST_PARAMETER_FUNCTION( (return-type-computed-from-arguments), policy, tag, // 3. namespace of tag types (optional // optional parameters, with defaults (domain_error, *, throw_on_error) ) (deduced (optional (precision, *, boost::mpl::int_<53>()) ) ) ) { // what type are the arguments? } I realise I can do this with an argument pack, but then either my users will have to call the function with an extra set of parenthesis, or I will have to write a bunch of forwarding functions myself - which itself generates a "what the is the return type" problem. >From within the body of the BOOST_PARAMETER_FUNCTION generated function it appears that I can use the name "Args" to refer to the type of the argument pack, and maybe in the return type as well? But this isn't documented, so can I rely on it? 2) All the arguments I want to pass are actually going to end up being used in meta-programs: for symbolic values, I can make each one a unique enum type, and use the type of the argument (even though it's actually passed as a value) to generate my metacode. But I have one optional argument where I require the value to be an arbitrary compile time constant, the only interface I can come up with at present is something like: policy(_digits10 = mpl::int_<10>()); But I'd really like to be able to write: policy(_digits10 = 12); and have the "12" converted to mpl::int_<12> "by magic", but I can't think of any magic that could be applied here... anyone any ideas? Thanks, John.

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Boost 1.34 and VC++ x64
by Cory Nelson 05 Jun '07

05 Jun '07

This was pretty straightforward for 1.33, but 1.34 using BB2 seems to have changed things a bit. There doesn't seem to be any documentation on compiling 1.34 for x64 with VC++ - can anyone offer some insight?

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Boost python: cannot compile lambda
by chun ping wang 04 Jun '07

04 Jun '07

---------- Forwarded message ---------- From: chun ping wang <cablepuff(a)gmail.com> Date: May 31, 2007 1:24 PM Subject: Boost python: cannot compile lambda To: boost-users(a)list.boost.org hi , while trying to compile boost.python i get these following errors. ar: creating ./lib/libOperatingSystem.a ranlib ./lib/libOperatingSystem.a rm -f ./lib/DeadLockAvoid.o ./lib/ContainerOperation.o make[1]: Leaving directory `C:/CPW/cs_classes' g++.exe -Wall -D__DEBUG__ -c ./cs540/c++/DeadLockPythonWrapper.cpp -o ./boost_py thon/DeadLockPythonWrapper.o -I"C:/Boost/include/boost_1_34" -I"C:/Python25/inc lude" -I"./Scripts" -ansi -fexceptions -fverbose-asm -fexpensive-optimization s -O3 -pg -g3 In file included from ./cs540/c++/DeadLockPythonWrapper.cpp:7: ./cs540/c++/cppdef/ContainerOperation.cpp: In function `CONT<T, std::allocator<_ CharT> > operator-(CONT<T, std::allocator<_CharT> >, CONT<T, std::allocator<_Cha rT> >)': ./cs540/c++/cppdef/ContainerOperation.cpp:32: error: `_1' undeclared (first use this function) ./cs540/c++/cppdef/ContainerOperation.cpp:32: error: (Each undeclared identifier is reported only once for each function it appears in.) ./cs540/c++/cppdef/ContainerOperation.cpp:32: error: `_2' undeclared (first use this function) ./cs540/c++/cppdef/ContainerOperation.cpp: In function `CONT<T, std::allocator<_ CharT> > operator+(CONT<T, std::allocator<_CharT> >, CONT<T, std::allocator<_Cha rT> >)': ./cs540/c++/cppdef/ContainerOperation.cpp:44: error: `_1' undeclared (first use this function) ./cs540/c++/cppdef/ContainerOperation.cpp:44: error: `_2' undeclared (first use this function) ./cs540/c++/cppdef/ContainerOperation.cpp: In function `CONT<T, std::allocator<_ CharT> > operator*(CONT<T, std::allocator<_CharT> >, CONT<T, std::allocator<_Cha rT> >)': ./cs540/c++/cppdef/ContainerOperation.cpp:56: error: `_1' undeclared (first use this function) ./cs540/c++/cppdef/ContainerOperation.cpp:56: error: `_2' undeclared (first use this function) ./cs540/c++/cppdef/ContainerOperation.cpp: In function `CONT<T, std::allocator<_ CharT> > operator/(CONT<T, std::allocator<_CharT> >, CONT<T, std::allocator<_Cha rT> >)': ./cs540/c++/cppdef/ContainerOperation.cpp:68: error: `_1' undeclared (first use this function) ./cs540/c++/cppdef/ContainerOperation.cpp:68: error: `_2' undeclared (first use this function) ./cs540/c++/cppdef/ContainerOperation.cpp: In function `CONT<T, std::allocator<_ CharT> > operator%(CONT<T, std::allocator<_CharT> >, CONT<T, std::allocator<_Cha rT> >)': ./cs540/c++/cppdef/ContainerOperation.cpp:80: error: `_1' undeclared (first use this function) ./cs540/c++/cppdef/ContainerOperation.cpp:80: error: `_2' undeclared (first use this function) Is there a way to integerate lambda into boost python. OperatingSystemLib.mak works .. i just can't put lambda inside implementation file for boost.python. thanks.

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[multi_index] MSVS 2005 visualizers?
by Filip Konvička 04 Jun '07

04 Jun '07

Hi, I just wanted to know if anyone succeeded creating a visualizer for multi_index containers. I'd love to spend some time doing that for the good of the community (and my own, of course :-)), but I could not find any data members for exploration in the debugger's watch window. Any suggestions? See the following blog for more info: http://www.virtualdub.org/blog/pivot/entry.php?id=120 Some info can be found in the autoexp.dat file directly - there are pre-defined visualizers for eg. std::map (which works nice). Thanks, Filip

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[date_time] UNICODE and wcout problems
by Filip Konvička 04 Jun '07

04 Jun '07

Hi, in MSVC 8.0 _UNICODE build, after I send a ptime to wcout, I can no longer print "international" characters. When I use a temporary wostringstream for printing the ptime, everything is OK. Minimal repro see below (the "2" at the end is never printed). With some characters like the "š" in the example, the output is totally cut off; with others, like "á", the codepage is changed, so the characters are displayed incorrectly. Any suggestions? Thanks, Filip // _UNICODE must be defined; the "2" is never printed. #include <string> #include <iostream> #include <sstream> #include <locale.h> #include <boost/date_time/posix_time/posix_time.hpp> using boost::posix_time::ptime; using boost::date_time::not_a_date_time; int main() { wstring intl=L"\x161"; wostringstream ss; ss << ptime(not_a_date_time); wcout << ss.str() << endl; wcout << intl << endl; wcout << L"1" << endl; wcout << ptime(not_a_date_time) << endl; wcout << intl << endl; wcout << L"2" << endl; }

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[interprocess]
by Aaron W. LaFramboise 03 Jun '07

03 Jun '07

I just got Boost.Interprocess working, and it's really an amazing library. Ion, it's obvious you've put a lot of time into this library, and the result is really nice. However, I've had these issues so far: (1) Is there a way to get a managed_shared_memory segment to tell me allocation statistics? What I'd like is something that can tell me. (a) Segment size (b) Allocated memory (c) Most importantly, free memory (2) It's been brought up before, but there seriously needs to be a way to grow managed shared memory segments. I understand that this is really tricky to implement, and probably just as tricky to use safely, but it's an important feature, in my opinion. I guess the main difficulties here are the potential change of base, and atomicity? (3) Regarding priv_open_or_create() in managed_open_or_create_impl.hpp, this implementation creates some small annoyances for me by throwing. I don't have any idea how to tell if POSIX O_CREAT actually created anything or not. However, I'm using Windows, and on Windows, you always can tell, as far as I know, both for file creation and named shared memory object creation. Would it be difficult to avoid throwing for the Windows case?

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