October 2010 - Boost-users - lists.preview.boost.org

[shared_ptr] Better support for allocators
by Alex Dubov 12 Oct '10

12 Oct '10

Greetings. shared_ptr<> can be constructed with both custom allocator and deleter. However, there's an unfortunate shortcoming: if the held object needs to do some unusual housekeeping on itself during destruction, it needs to store an additional copy of the allocator or rely on some other custom functionality. It would be considerably more convenient, if shared_ptr<> could invoke a custom deleter with allocator (optionally) supplied: virtual void sp_counted_impl_pda::dispose() { d_(p_, a_); } Another handy alternative is to be able to obtain the allocator out of shared_ptr<> explicitly, in a manner similar to get_deleter(). Tr1 implementation actually constructs a proxy deleter object around the user supplied one, which inherits from allocator, but it's impossible to obtain a reference to it from the outside.

1 0

Variadic Macro Data library in the Boost sandbox
by Edward Diener 12 Oct '10

12 Oct '10

This may interest end-users who use macros/Boost PP in their own code to do preprocessor metaprogramming. I have put in the Boost sandbox the Variadic Macro Data library, or VMD. This library supplies variadic macro functionality and integrates variadic macros with the Boost PP library without changing the latter in any way. The library in the sandbox is in the variadic_macro_data folder. The library is a header-only library of macros. There is documentation and tests and the appropriate jamfiles for both. To build the documentation you need doxygen but I have also provided documentation in an html subfolder. Access to the Boost sandbox is explained on the Boost web site at http://www.boost.org/community/sandbox.html. The main use of the library is to be able to pass variadic data to macros, and in particular to extract variadic data elements or convert variadic data to Boost PP data types for use by Boost PP. The library also enhances the functionality of Boost PP tuple data. Installation is simply to take the boost and lib subfolders of the library and copy them to a Boost installation, preferable the trunk where support for variadic macros has been added in Boost config in the form of a BOOST_NO_VARIADIC_MACROS which is defined for compilers/versions which do NOT support variadic macros. To use the macros in the library, just "#include <boost/variadic_macro_data/VariadicMacroData.hpp>". Compilers which support variadic macros are gcc 3.0 and above and VC8 and above among a few others. You could also use the library on any installed Boost installation if the compiler you are using supports variadic macros. There is a discussion in the doc of why you might choose to use variadic macros rather than a Boost PP data type in a macro tailored for end-users. Comments, suggestions, and bug reports are welcome. Edward Diener

1 0

[array][bind] Binding boost array to a boost function
by Ryan McConnehey 11 Oct '10

11 Oct '10

I'm trying to bind a boost array to be called at a later time. This is giving me a lot of errors. Is what I'm attempting possible? Ryan template<typename T, std::size_t U> class Sorter { private: typedef boost::function<void(boost::array<T, U> & a)> t_SortFunction; t_SortFunction m_SortFunction; public: Sorter(t_SortFunction func) : m_SortFunction(func) {} bool sort(boost::array<T, U> & a) { m_SortFunction(a); } }; template<typename T, std::size_t U> void quicksort(boost::array<T, U> & a) { } int main(int argc, char* argv[]) { Sorter shell(boost::bind(quicksort, _1)); return 0; }

3 4

[filesystem][v3] remove_all and system::error_code error?
by valblade 11 Oct '10

11 Oct '10

Hi everyone, First of all, I want to thanks boost::filesystem contributors for their amazing work. I have a question in the recent filesystem V3. when using boost::uintmax_t remove_all(const path& p, system::error_code* ec=0); like this : ----------- listing ----------------------- remove_all("C:\\test_path_to_delete"); ------------- end listing --------------- the "C:\\test_path_to_delete" (and its descendent) is successfully deleted (as described in documentation) but when I use it like this : ----------- listing ----------------------- boost::system::error_code ec; remove_all("C:\\test_path_to_delete", ec); ------------- end listing --------------- The directory (and it descendent) aren't removed at all. I have investigated and, I found the following : boost::uintmax_t remove_all_aux(const path& p, fs::file_status sym_stat, error_code* ec) { boost::uintmax_t count = 1; if (!fs::is_symlink(sym_stat)// don't recurse symbolic links && fs::is_directory(sym_stat)) { for (fs::directory_iterator itr(p); itr != end_dir_itr; ++itr) { fs::file_status tmp_sym_stat = fs::symlink_status(itr->path(), *ec); HERE=> if (ec != 0 && ec) return count; count += remove_all_aux(itr->path(), tmp_sym_stat, ec); } } remove_file_or_directory(p, sym_stat, ec); return count; } This function is called by remove_all. Here, ec is passed by address. When remove_all("C:\\test_path_to_delete"); is called, &ec = 0 (default argument) so the check if (ec != 0 && ec) will never hit. But when called with remove_all("C:\\test_path_to_delete", ec); ec is allocated and &ec != 0, the check if (ec != 0 && ec) is allways true, and the function returns at the first iteration, I'm maybe wrong, but, isn't this what you meant to do? if (ec != 0 && *ec) return count; Sorry if I have misunderstood something... Thanks again.

1 0

Re: [Boost-users] boost 1.44.0 undefined reference to boost::filesystem2::no_check
by Asif Fayyaz 11 Oct '10

11 Oct '10

Any one?? any idea? Waiting for response in this regard. Asif -- Muhammad Asif Fayyaz Address: 42A:10 Kista Allevag. 16455 Kista Stockholm Sweden. Mobile: (+46)0707446631 Profile: http://www.isk.kth.se/~mafayyaz/

2 1

[asio] accepting all connections in a seperate thread - how?
by for-gmane 11 Oct '10

11 Oct '10

My server app needs to be "highly responsive". Ie. it shall handle connection attemps with a higher priority. Currently it has the following problem: if a handler function like the one below takes too much time, then unfortunately no new connections will be handled as long as the operation below lasts (ie. new connections have to wait). Which alternatives are there to solve this problem? (I was thinking of doing the accept in a seperate thread, but not sure how and whether that would work?) void session::handle_read(const boost::system::error_code& error, size_t bytes_transferred) { if (!error) { // PROBLEM HERE: // ... a lengthy job here blocks the whole app (ie. new connections have to wait) // ... which coding/design alternatives would solve this problem? boost::asio::async_write(socket_, boost::asio::buffer(data_, bytes_transferred), boost::bind(&session::handle_write, this, boost::asio::placeholders::error)); } else { delete this; } }

3 5

AIX and Boost.PropertyTree
by Will Mason 10 Oct '10

10 Oct '10

Hello, I'm using Boost 1.42, IBM XL C++ 10.1, and AIX 5.3. I'm running into trouble building code that uses Boost.PropertyTree. I get errors compiling the following code, which works fine on numerous other platforms: boost::property_tree::ptree pt; pt.put(LOG_FILE_KEY, props.log_file_name()); pt.put(LOG_LEVEL_KEY, props.log_level()); pt.put(LOG_NAME_KEY, props.log_name()); pt.put(LOG_FILE_SIZE_MAX_KEY, props.log_file_max_size()); pt.put(LOG_TO_CONSOLE_KEY, props.log_to_console()); pt.put(MESSAGE_MAX_KEY, props.message_max_size()); pt.put(SCAN_THREADS_KEY, props.scan_threads()); std::ostringstream prop_info; boost::property_tree::ini_parser::write_ini(prop_info, pt); The errors, all of which are attributed to the last line of code above, are: "/home/wmason/src/cap-aix/fim/../opt/include/aix/boost/v1.42/boost/property_tree/detail/ptree_implementation.hpp", line 55.28: 1540-0129 (S) The qualifier "subs" is not defined in the current scope. "/home/wmason/src/cap-aix/fim/../opt/include/aix/boost/v1.42/boost/property_tree/detail/ptree_implementation.hpp", line 78.34: 1540-0129 (S) The qualifier "subs" is not defined in the current scope. "/home/wmason/src/cap-aix/fim/../opt/include/aix/boost/v1.42/boost/property_tree/detail/ptree_implementation.hpp", line 91.42: 1540-0716 (S) The template argument "boost::iterator" does not match the template parameter "class Iterator". "/home/wmason/src/cap-aix/fim/../opt/include/aix/boost/v1.42/boost/property_tree/detail/ptree_implementation.hpp", line 101.42: 1540-0274 (S) The name lookup for "const_iterator" did not find a declaration. "/home/wmason/src/cap-aix/fim/../opt/include/aix/boost/v1.42/boost/property_tree/detail/ptree_implementation.hpp", line 101.42: 1540-1226 (I) Declarations for non-dependent names are resolved in the template definition. "/home/wmason/src/cap-aix/fim/../opt/include/aix/boost/v1.42/boost/property_tree/detail/ptree_implementation.hpp", line 101.42: 1540-1227 (I) "const_iterator" does not depend on a template argument. "/home/wmason/src/cap-aix/fim/../opt/include/aix/boost/v1.42/boost/property_tree/detail/ptree_implementation.hpp", line 116.51: 1540-0129 (S) The qualifier "subs" is not defined in the current scope. "/home/wmason/src/cap-aix/fim/../opt/include/aix/boost/v1.42/boost/property_tree/detail/ptree_implementation.hpp", line 138.45: 1540-0129 (S) The qualifier "subs" is not defined in the current scope. "/home/wmason/src/cap-aix/fim/../opt/include/aix/boost/v1.42/boost/property_tree/detail/ptree_implementation.hpp", line 78.34: 1540-0129 (S) The qualifier "subs" is not defined in the current scope. "/home/wmason/src/cap-aix/fim/../opt/include/aix/boost/v1.42/boost/property_tree/ini_parser.hpp", line 231.45: 1540-0700 (I) The previous message was produced while processing "class boost::property_tree::basic_ptree<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::basic_string<char,std::char_traits<char>,std::allocator<char> >,struct std::less<std::basic_string<char,std::char_traits<char>,std::allocator<char> > > >::const_iterator". The release notes for Boost 1.42 at http://www.boost.org/users/news/version_1_42_0 claim that my combination of OS, compiler and Boost version are supported. I was wondering if anyone might know of a way around this problem besides not using Boost.PropertyTree. Thanks very much for any help, Will

3 3

[fusion] deduce type of resulting vector from a transformation
by alfC 10 Oct '10

10 Oct '10

Hi, (I keep struggling with Boos.Fusion.) How do I deduce the type of the vector resulting from the transformation of another vector? I have a source vector of different types, e.g. vector<quantity<si::length>, quantity<si::mass>, quantity<si::time> > and I have a transformation that is well defined and returns another type depending on the original type. The question is how do I generate a vector type that is the result of the given transformation. I though that result_of::transform was the function to obtain the result but it turns not because it returns a type transform_view instead of a vector. vector< ... > v1; T? v2(transform(v1, transformation())); i.e. what is the type of T as a fusion::vector as deduced from the type of v1 and the transformation type? -- Thank you, Alfredo-- Below is the illustrative code: #include<boost/array.hpp> #include <boost/fusion/container.hpp> #include <boost/fusion/algorithm/transformation/zip.hpp> #include <boost/units/systems/si.hpp> #include<iostream> using std::clog; using std::endl; using namespace boost::fusion; using namespace boost::units; // this is the transformation struct divide{ template <typename SignatureT> struct result; template<class Q> struct result<divide(Q const&)>{ typedef typename divide_typeof_helper<Q, quantity<si::time> >::type type; }; template<typename Q> typename result<divide(Q const&)>::type operator()(Q const& q) const { return q/quantity<si::time>(1.*si::second); } }; int main(){ typedef vector< quantity<si::length>, quantity<si::mass>, quantity<si::time> > source_type ; source_type v1(1.*si::meter, 2.*si::kilogram, 3.*si::second); clog << "v1: " << at_c<0>(v1) << ", "<< at_c<1>(v1) << ", " << at_c<2>(v1) << endl; // how can I deduce the result_type from the type "divide"? // here manually defined typedef vector< divide_typeof_helper<quantity<si::length>, quantity<si::time> >::type, divide_typeof_helper<quantity<si::mass>, quantity<si::time> >::type, divide_typeof_helper<quantity<si::time>, quantity<si::time> >::type > result_type ; result_type v2( boost::fusion::transform(v1, divide() ) ); clog << "v2: " << at_c<0>(v2) << ", "<< at_c<1>(v2) << ", " << at_c<2>(v2) << endl; return 0; }

3 4

[boost-install]update old version to new one by 'bjam install'
by hongleij 10 Oct '10

10 Oct '10

i have install 1.43 version in my system,after use “./bjam install” to intall boost1.44,i met the following error. [root@localhost gridcast]# g++ -o datetime datetime_tcp_async_server.cpp -lpthread -lboost_system -L/usr/local/lib datetime_tcp_async_server.cpp:142:2: 警告：文件未以空白行结束 /tmp/ccjG0R2d.o: In function `__static_initialization_and_destruction_0(int, int)': datetime_tcp_async_server.cpp:(.text+0x16c): undefined reference to `boost::system::get_system_category()' datetime_tcp_async_server.cpp:(.text+0x176): undefined reference to `boost::system::get_generic_category()' datetime_tcp_async_server.cpp:(.text+0x180): undefined reference to `boost::system::get_generic_category()' datetime_tcp_async_server.cpp:(.text+0x18a): undefined reference to `boost::system::get_generic_category()' datetime_tcp_async_server.cpp:(.text+0x194): undefined reference to `boost::system::get_system_category()' /tmp/ccjG0R2d.o: In function `boost::asio::error::get_system_category()': datetime_tcp_async_server.cpp:(.text._ZN5boost4asio5error19get_system_categoryEv[boost::asio::error::get_system_category()]+0x7): undefined reference to `boost::system::get_system_category()' /tmp/ccjG0R2d.o: In function `boost::system::error_code::error_code()': datetime_tcp_async_server.cpp:(.text._ZN5boost6system10error_codeC1Ev[boost::system::error_code::error_code()]+0x10):undefined reference to `boost::system::get_system_category()' collect2: ld 返回 1 so i delete /usr/local/include/boost dir ,and rerun ”./bjam install” -bash-3.2# g++ datetime_tcp_async_server.cpp -lpthread datetime_tcp_async_server.cpp:142:2: warning: no newline at end of file /tmp/ccQeKssV.o: In function `__static_initialization_and_destruction_0(int, int)': datetime_tcp_async_server.cpp:(.text+0x176): undefined reference to `boost::system::generic_category()' datetime_tcp_async_server.cpp:(.text+0x182): undefined reference to `boost::system::generic_category()' datetime_tcp_async_server.cpp:(.text+0x18e): undefined reference to `boost::system::system_category()' /tmp/ccQeKssV.o: In function `boost::system::get_system_category()': datetime_tcp_async_server.cpp:(.text._ZN5boost6system19get_system_categoryEv[boost::system::get_system_category()]+0x5): undefined reference to `boost::system::system_category()' /tmp/ccQeKssV.o: In function `boost::system::error_code::error_code()': datetime_tcp_async_server.cpp:(.text._ZN5boost6system10error_codeC1Ev[boost::system::error_code::error_code()]+0x17): undefined reference to `boost::system::system_category()' collect2: ld returned 1 exit status --------------------------------- the name changed from `boost::system::get_generic_category()' to `boost::system::generic_category()',so it seems if i already have an old version of boost,i need remove it clearly to reinstall the new one by myself.

2 3

[boost.datetime] query
by Sean Farrow 10 Oct '10

10 Oct '10

Hi: Is it possible to return a number representing the date. Like you can with COleDateTime.m_dt; Any help appreciated. Regards Sean.

3 2