August 2010 - Boost - lists.preview.boost.org

accurate sum accumulator (kahan)
by Gaetano Mendola 27 Apr '11

27 Apr '11

Hi all, I had to implement in terms of boost accumulators the Kahan summation algorithm. I will paste at the end of this message the accumulator, the feature and the extractor source code. This accumulator reduces the numerical error obtained with standard sequential sum, as example the sum of 1e6f elements equal to 1e-6f should give 1.0f, this is the results obtained with sum and sum_kahan: tag::sum: 1.009038925 tag::sum_kahan: 1.000000000 I'm not sure if that sum_kahan is worth to be inserted in the accumulators provided with boost, I'm not an expert of boost:accumulators (I just followed the guide to make this new accumulator) so not sure if you prefer to have a fast_sum and an accurate_sum instead of sum and sum_kahan. Regards Gaetano Mendola // File kahan_sum.hpp #ifndef KAHAN_SUM #define KAHAN_SUM #include <boost/accumulators/framework/accumulator_base.hpp> #include <boost/accumulators/framework/parameters/sample.hpp> #include <boost/numeric/conversion/cast.hpp> namespace boost { namespace accumulators { namespace impl { template<typename Sample> struct sum_kahan_accumulator : accumulator_base { typedef Sample result_type; template<typename Args> sum_kahan_accumulator(Args const & args) : sum(args[sample | Sample()]), compensation(boost::numeric_cast<Sample>(0.0)) { } template<typename Args> void operator ()(Args const & args) { const Sample myTemp1 = args[sample] - this->compensation; const Sample myTemp2 = this->sum + myTemp1; this->compensation = (myTemp2 - this->sum) - myTemp1; this->sum = myTemp2; } result_type result(dont_care) const { return this->sum; } private: Sample sum; Sample compensation; }; }}} namespace boost { namespace accumulators { namespace tag { struct sum_kahan : depends_on< > { typedef impl::sum_kahan_accumulator< mpl::_1 > impl; }; }}} namespace boost { namespace accumulators { namespace extract { extractor< tag::sum_kahan > const sum_kahan = {}; } using extract::sum_kahan; }} #endif

21 68

[scope_exit] MSVC error C2355: 'this' : can only be referenced inside non-static member functions
by Lorenzo Caminiti 01 Mar '11

01 Mar '11

Hello all, I am trying to use Boost.ScopeExit parameter binding mechanism to implement Boost.LocalFunction. To do so, I need to use some internal ScopeExit code to detect the type of `this` and bind its value to the local function declaration. The following code works on GCC but not on MSVC... This appears to be a MSVC 2008 bug: http://connect.microsoft.com/VisualStudio/feedback/details/331418/erroneous… 1) Can anyone please try this code on MSVC versions later than 2008 to see if it was fixed? 2) Do you know of a workaround for this problem? // File: lf03.cpp #include <boost/scope_exit.hpp> struct c { void f() { typedef void (*this_t)(int this_ ); #if defined(BOOST_MSVC) // for MSVC typedef boost::type_of::msvc_typeid_wrapper< sizeof(*boost::type_of::encode_start( #else // for GCC typedef __typeof__( boost::type_of::ensure_obj( #endif boost::scope_exit::aux::wrap( boost::scope_exit::aux::deref( this, (this_t)0 ) ) ) #if defined(BOOST_MSVC) // for MSVC )>::type #else // for GCC ) #endif this_w; } }; int main() { c cc; cc.f(); return 0; } I get this error on MSVC 2008 but the code compiles just fine on GCC: Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 14.00.50727.42 for 80x86 Copyright (C) Microsoft Corporation. All rights reserved. lf03.cpp using native typeof lf03.cpp(17) : error C2355: 'this' : can only be referenced inside non-static member functions lf03.cpp(22) : error C2955: 'boost::type_of::msvc_typeid_wrapper' : use of class template requires template argument list C:\Program Files\boost\boost_1_42\boost/typeof/msvc/typeof_impl.hpp(212) : see declaration of 'boost::type_of::msvc_typeid_wrapper' Thank you very much. -- Lorenzo

5 8

[serialization] boost/serialization/path.hpp
by Johan Råde 21 Feb '11

21 Feb '11

There is no boost/serialization/path.hpp. I suggest the following: ---------------------------------------------------------------------------------------------------------------- #ifndef BOOST_SERIALIZATION_PATH_HPP #define BOOST_SERIALIZATION_PATH_HPP // MS compatible compilers support #pragma once #if defined(_MSC_VER) && (_MSC_VER >= 1020) #pragma once #endif #include <boost/config.hpp> #include <boost/filesystem/path.hpp> #include <boost/serialization/level.hpp> BOOST_CLASS_IMPLEMENTATION(boost::filesystem::path, boost::serialization::primitive_type) #ifndef BOOST_NO_STD_WSTRING BOOST_CLASS_IMPLEMENTATION(boost::filesystem::wpath, boost::serialization::primitive_type) #endif namespace boost { namespace serialization { template<class Archive, class String, class Traits> void serialize(Archive& ar, boost::filesystem::basic_path<String, Traits>& p, const unsigned int version) { String s; if(Archive::is_saving::value) s = p.string(); ar & boost::serialization::make_nvp("string", s); if(Archive::is_loading::value) p = s; } }} #endif //-------------------------------------------------------------------------------------------------------------- Comments? Any suggested improvements? --Johan Råde

5 11

[C++0x] Emulation of scoped enums
by Beman Dawes 16 Feb '11

16 Feb '11

The improved type safety of the C++0x scoped enum feature is attractive, so I'd like to start using it as it becomes available in compilers. See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2347.pdf for a description. Note that the committee changed the name from strongly typed enums to scoped enums. See the attached for a boost/detail header that provides macro wrappers that use scoped enums if available, otherwise fall back on C++03 namespaces and unscoped enums. It lets a library write: BOOST_SCOPED_ENUM_START(algae) { green, red, cyan }; BOOST_SCOPED_ENUM_END ... BOOST_SCOPED_ENUM(algae) sample( algae::red ); void func(BOOST_SCOPED_ENUM(algae)); and then a user can write: sample = algae::green; func( algae::cyan ); Comments or suggestions appreciated, --Beman // scoped_enum_emulation.hpp ---------------------------------------------------------// // Copyright Beman Dawes, 2009 // Distributed under the Boost Software License, Version 1.0. // See http://www.boost.org/LICENSE_1_0.txt // Generates C++0x scoped enums if the feature is present, otherwise emulates C++0x // scoped enums with C++03 namespaces and enums. The Boost.Config BOOST_NO_SCOPED_ENUMS // macro is used to detect feature support. // // Caution: only the syntax is emulated; the semantics are not emulated and // the syntax emulation doesn't include being able to specify the underlying type. // // See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2347.pdf for a // description of the feature. Note that the committee changed the name from // strongly typed enums to scoped enums. // // Sample usage: // // BOOST_SCOPED_ENUM_START(algae) { green, red, cyan }; BOOST_SCOPED_ENUM_END // ... // BOOST_SCOPED_ENUM(algae) sample( algae::red ); // void foo( BOOST_SCOPED_ENUM(algae) color ); // ... // sample = algae::green; // foo( algae::cyan ); #ifndef BOOST_SCOPED_ENUM_EMULATION_HPP #define BOOST_SCOPED_ENUM_EMULATION_HPP #include <boost/config.hpp> #ifndef BOOST_NO_SCOPED_ENUMS # define BOOST_SCOPED_ENUM_START(name) enum class name # define BOOST_SCOPED_ENUM_END # define BOOST_SCOPED_ENUM(name) name #else # define BOOST_SCOPED_ENUM_START(name) namespace name { enum enum_t # define BOOST_SCOPED_ENUM_END } # define BOOST_SCOPED_ENUM(name) name::enum_t #endif #endif // BOOST_SCOPED_ENUM_EMULATION_HPP

14 27

[process] How to run test cases
by Boris 23 Jan '11

23 Jan '11

As Boost.Process 0.3 has been released it would be great if the test cases are run on various platforms. So far I've tested Boost.Process on WinXP with MSVC 9.0, Cygwin with g++ 3.4.4 and Solaris with g++ 3.4.6 and Sun C++ 5.9. To make it as easy as possible for others to run the test cases here's a short description of how to proceed. Nearly all test cases depend on a program called "helpers". This program is built first and is started by many test cases as a child process. In order to find the program "helpers" the test cases must know its location. As there is no way to get the location at runtime it is hardcoded in the file libs/process/test/misc.hpp. As the location differs depending on what compiler is used YOU MUST CHECK FIRST THE PATH IN libs/process/test/misc.hpp! Otherwise most of the test cases will fail as they look for a program "helpers" in the wrong directory. As of today only those paths are correct and have been tested which are set for Windows, Cygwin and Solaris. Only after you have checked and maybe updated the path in libs/process/test/misc.hpp you should try to build and run the test cases: WinXP/MSVC 9.0 ************** With MSVC 9.0 you only need to open the Visual Studio 2008 Command Prompt, change to the directory with the test cases and run bjam: C:\boost_1_36_0\libs\process\test> ..\..\..\bjam.exe -q Cygwin/GCC 3.4.4 **************** On Cygwin it's important to know if the Boost libraries have been built for the POSIX or Windows API. By default Boost libraries on Cygwin use the Windows API. With the Windows API the Boost.Process test cases are not passed successfully though (there are compiler errors where I'm not sure currently if they are a Boost.Process problem and how they could be fixed). If you want to run the test cases on Cygwin you must (re-)build the Boost libraries to use the POSIX API: $ cd ~/boost_1_36_0 $ ./bjam cxxflags=-DBOOST_POSIX_API Afterwards you can run the test cases: $ cd ~/boost_1_36_0/libs/process/test $ ../../../bjam cxxflags=-DBOOST_POSIX_API -q Solaris/GCC 3.4.6 ***************** At first you have to put the following line in ~/user-config.jam: using gcc : : : <linker-type>sun ; Then start building the Boost libraries: $ cd ~/boost_1_36_0 $ ./bjam --toolset=gcc cxxflags=-mcpu=ultrasparc For the test cases to be passed successfully you must update Boost.Test. Change line 624 in ~/boost_1_36_0/boost/test/impl/execution_monitor.ipp temporarily to: - , m_CHLD_action( SIGCHLD, catch_system_errors, attach_dbg, alt_stack ) + , m_CHLD_action( SIGCHLD, false, attach_dbg, alt_stack ) It is important that the second parameter is false as the signal SIGCHLD should not be handled by the execution monitor and should not be reported as an error. Afterwards the test cases can be run: $ cd ~/boost_1_36_0/libs/process/test $ ../../../bjam --toolset=gcc cxxflags=-mcpu=ultrasparc -q Solaris/Sun C++ 5.9 ******************* Build the Boost libraries with the sun toolset: $ cd ~/boost_1_36_0 $ ./bjam --toolset=sun stdlib=sun-stlport For the test cases to be passed successfully you must update Boost.Test. Change line 624 in ~/boost_1_36_0/boost/test/impl/execution_monitor.ipp temporarily to: - , m_CHLD_action( SIGCHLD, catch_system_errors, attach_dbg, alt_stack ) + , m_CHLD_action( SIGCHLD, false, attach_dbg, alt_stack ) It is important that the second parameter is false as the signal SIGCHLD should not be handled by the execution monitor and should not be reported as an error. If you run the test cases now you'll get this compiler error for one test case: "../../../boost/asio/detail/socket_ops.hpp", line 218: Error: Cannot assign void* to char*. "../../../boost/asio/detail/socket_ops.hpp", line 229: Error: Cannot assign void* to char*. "../../../boost/asio/detail/descriptor_ops.hpp", line 66: Error: Cannot assign void* to char*. "../../../boost/asio/detail/descriptor_ops.hpp", line 72: Error: Cannot assign void* to char*. The bug has been reported to the Boost.Asio mailing list. If you want to build that one test case, too, you need to fix the two files in Boost.Asio 1.36.0 yourself. All the test cases can be built and run with: $ cd ~/boost_1_36_0/libs/process/test $ ../../../bjam --toolset=sun stdlib=sun-stlport -q

4 9

[SoC] BGL project idea
by Gautam Sewani 03 Jan '11

03 Jan '11

Hi, I am a Computer Science student hoping to contribute to Boost for this year's summer of code. I had a few questions regarding the BGL project idea (https://svn.boost.org/trac/boost/wiki/SoC2010#Boost.Graph) for SOC 2010. 1. I can think of only a few places where the suggested algorithms will be used. Does the community think that these algorithms are used frequently enough to put them in a library? How important does the community consider this project? 2. Will the project proposal be expected to include the API design? Thanks and Regards Gautam

5 29

[GIL] [patch] read multipage TIFF files
by Robert Pollak 29 Nov '10

29 Nov '10

Hello, the following patch (against the current trunk) allows to read any page of a multipage TIFF file, by optionally specifying the zero-based directory number. (The correct term for a TIFF page is "directory".) It adds a "dirnum" to the relevant functions, and uses the corresponding libtiff functionality. The "dirnum" default value is 0 for compatibility with present callers. Additionally, it defines the function tiff_get_directory_count to get the number of directories in the TIFF file. Please give me some feedback or consider applying the patch. This patch would close the corresponding feature request https://svn.boost.org/trac/boost/ticket/2373 . Credits go to Roland Richter, whose code the patch is based on. Best Regards, Robert Pollak Index: boost/gil/extension/io/tiff_io.hpp =================================================================== --- boost/gil/extension/io/tiff_io.hpp (revision 64065) +++ boost/gil/extension/io/tiff_io.hpp (working copy) @@ -122,9 +122,13 @@ protected: TIFF *_tp; public: - tiff_reader(const char* filename) { + tiff_reader(const char* filename,tdir_t dirnum=0) { io_error_if((_tp=TIFFOpen(filename,"r"))==NULL, "tiff_reader: fail to open file"); + if(dirnum>0) { + io_error_if(TIFFSetDirectory(_tp,dirnum)!=1, + "tiff_reader: fail to set directory"); + } } ~tiff_reader() { TIFFClose(_tp); } template <typename View> @@ -171,10 +175,10 @@ private: CC _cc; public: - tiff_reader_color_convert(const char* filename) : - tiff_reader(filename) {} - tiff_reader_color_convert(const char* filename,CC cc_in) : - tiff_reader(filename),_cc(cc_in) {} + tiff_reader_color_convert(const char* filename,tdir_t dirnum=0) : + tiff_reader(filename,dirnum) {} + tiff_reader_color_convert(const char* filename,CC cc_in,tdir_t dirnum=0) : + tiff_reader(filename,dirnum),_cc(cc_in) {} template <typename View> void apply(const View& view) { point2<std::ptrdiff_t> dims=get_dimensions(); @@ -336,18 +340,34 @@ }; /// \ingroup TIFF_IO +/// \brief Returns the number of directories in the TIFF file +inline int tiff_get_directory_count(const char* filename) { + TIFF *tif; + io_error_if((tif=TIFFOpen(filename,"r"))==NULL, + "tiff_get_count: fail to open file"); + + int dircount = 0; + do { + dircount++; + } while (TIFFReadDirectory(tif)); + + TIFFClose(tif); + return dircount; +} + +/// \ingroup TIFF_IO /// \brief Returns the width and height of the TIFF file at the specified location. /// Throws std::ios_base::failure if the location does not correspond to a valid TIFF file -inline point2<std::ptrdiff_t> tiff_read_dimensions(const char* filename) { - detail::tiff_reader m(filename); +inline point2<std::ptrdiff_t> tiff_read_dimensions(const char* filename,tdir_t dirnum=0) { + detail::tiff_reader m(filename,dirnum); return m.get_dimensions(); } /// \ingroup TIFF_IO /// \brief Returns the width and height of the TIFF file at the specified location. /// Throws std::ios_base::failure if the location does not correspond to a valid TIFF file -inline point2<std::ptrdiff_t> tiff_read_dimensions(const std::string& filename) { - return tiff_read_dimensions(filename.c_str()); +inline point2<std::ptrdiff_t> tiff_read_dimensions(const std::string& filename,tdir_t dirnum=0) { + return tiff_read_dimensions(filename.c_str(),dirnum); } /// \ingroup TIFF_IO @@ -356,17 +376,17 @@ /// Throws std::ios_base::failure if the file is not a valid TIFF file, or if its color space or channel depth are not /// compatible with the ones specified by View, or if its dimensions don't match the ones of the view. template <typename View> -inline void tiff_read_view(const char* filename,const View& view) { +inline void tiff_read_view(const char* filename,const View& view,tdir_t dirnum=0) { BOOST_STATIC_ASSERT(tiff_read_support<View>::is_supported); - detail::tiff_reader m(filename); + detail::tiff_reader m(filename,dirnum); m.apply(view); } /// \ingroup TIFF_IO /// \brief Loads the image specified by the given tiff image file name into the given view. template <typename View> -inline void tiff_read_view(const std::string& filename,const View& view) { - tiff_read_view(filename.c_str(),view); +inline void tiff_read_view(const std::string& filename,const View& view,tdir_t dirnum=0) { + tiff_read_view(filename.c_str(),view,dirnum); } /// \ingroup TIFF_IO @@ -375,25 +395,25 @@ /// Throws std::ios_base::failure if the file is not a valid TIFF file, or if its color space or channel depth are not /// compatible with the ones specified by Image template <typename Image> -void tiff_read_image(const char* filename,Image& im) { +void tiff_read_image(const char* filename,Image& im,tdir_t dirnum=0) { BOOST_STATIC_ASSERT(tiff_read_support<typename Image::view_t>::is_supported); - detail::tiff_reader m(filename); + detail::tiff_reader m(filename,dirnum); m.read_image(im); } /// \ingroup TIFF_IO /// \brief Allocates a new image whose dimensions are determined by the given tiff image file, and loads the pixels into it. template <typename Image> -inline void tiff_read_image(const std::string& filename,Image& im) { - tiff_read_image(filename.c_str(),im); +inline void tiff_read_image(const std::string& filename,Image& im,tdir_t dirnum=0) { + tiff_read_image(filename.c_str(),im,dirnum); } /// \ingroup TIFF_IO /// \brief Loads and color-converts the image specified by the given tiff image file name into the given view. /// Throws std::ios_base::failure if the file is not a valid TIFF file, or if its dimensions don't match the ones of the view. template <typename View,typename CC> -inline void tiff_read_and_convert_view(const char* filename,const View& view,CC cc) { - detail::tiff_reader_color_convert<CC> m(filename,cc); +inline void tiff_read_and_convert_view(const char* filename,const View& view,CC cc,tdir_t dirnum=0) { + detail::tiff_reader_color_convert<CC> m(filename,cc,dirnum); m.apply(view); } @@ -401,31 +421,31 @@ /// \brief Loads and color-converts the image specified by the given tiff image file name into the given view. /// Throws std::ios_base::failure if the file is not a valid TIFF file, or if its dimensions don't match the ones of the view. template <typename View> -inline void tiff_read_and_convert_view(const char* filename,const View& view) { - detail::tiff_reader_color_convert<default_color_converter> m(filename,default_color_converter()); +inline void tiff_read_and_convert_view(const char* filename,const View& view,tdir_t dirnum=0) { + detail::tiff_reader_color_convert<default_color_converter> m(filename,default_color_converter(),dirnum); m.apply(view); } /// \ingroup TIFF_IO /// \brief Loads and color-converts the image specified by the given tiff image file name into the given view. template <typename View,typename CC> -inline void tiff_read_and_convert_view(const std::string& filename,const View& view,CC cc) { - tiff_read_and_convert_view(filename.c_str(),view,cc); +inline void tiff_read_and_convert_view(const std::string& filename,const View& view,CC cc,tdir_t dirnum=0) { + tiff_read_and_convert_view(filename.c_str(),view,cc,dirnum); } /// \ingroup TIFF_IO /// \brief Loads and color-converts the image specified by the given tiff image file name into the given view. template <typename View> -inline void tiff_read_and_convert_view(const std::string& filename,const View& view) { - tiff_read_and_convert_view(filename.c_str(),view); +inline void tiff_read_and_convert_view(const std::string& filename,const View& view,tdir_t dirnum=0) { + tiff_read_and_convert_view(filename.c_str(),view,dirnum); } /// \ingroup TIFF_IO /// \brief Allocates a new image whose dimensions are determined by the given tiff image file, loads and color-converts the pixels into it. /// Throws std::ios_base::failure if the file is not a valid TIFF file template <typename Image,typename CC> -void tiff_read_and_convert_image(const char* filename,Image& im,CC cc) { - detail::tiff_reader_color_convert<CC> m(filename,cc); +void tiff_read_and_convert_image(const char* filename,Image& im,CC cc,tdir_t dirnum=0) { + detail::tiff_reader_color_convert<CC> m(filename,cc,dirnum); m.read_image(im); } @@ -433,23 +453,23 @@ /// \brief Allocates a new image whose dimensions are determined by the given tiff image file, loads and color-converts the pixels into it. /// Throws std::ios_base::failure if the file is not a valid TIFF file template <typename Image> -void tiff_read_and_convert_image(const char* filename,Image& im) { - detail::tiff_reader_color_convert<default_color_converter> m(filename,default_color_converter()); +void tiff_read_and_convert_image(const char* filename,Image& im,tdir_t dirnum=0) { + detail::tiff_reader_color_convert<default_color_converter> m(filename,default_color_converter(),dirnum); m.read_image(im); } /// \ingroup TIFF_IO /// \brief Allocates a new image whose dimensions are determined by the given tiff image file, loads and color-converts the pixels into it. template <typename Image,typename CC> -inline void tiff_read_and_convert_image(const std::string& filename,Image& im,CC cc) { - tiff_read_and_convert_image(filename.c_str(),im,cc); +inline void tiff_read_and_convert_image(const std::string& filename,Image& im,CC cc,tdir_t dirnum=0) { + tiff_read_and_convert_image(filename.c_str(),im,cc,dirnum); } /// \ingroup TIFF_IO /// \brief Allocates a new image whose dimensions are determined by the given tiff image file, loads and color-converts the pixels into it. template <typename Image> -inline void tiff_read_and_convert_image(const std::string& filename,Image& im) { - tiff_read_and_convert_image(filename.c_str(),im); +inline void tiff_read_and_convert_image(const std::string& filename,Image& im,tdir_t dirnum=0) { + tiff_read_and_convert_image(filename.c_str(),im,dirnum); } /// \ingroup TIFF_IO

2 7

[gsoc] Boost.Process done
by Boris Schaeling 31 Oct '10

31 Oct '10

Here are the results of the Boost.Process project within this year's Google Summer of Code program: We have a complete library to manage system processes now! If you like to play around with the library download the ZIP file from <http://www.highscore.de/boost/gsoc2010/process.zip>. As it's a header-only library simply copy the files to your Boost folder. If you like to quickly check the documentation click on <http://www.highscore.de/boost/gsoc2010/>. The library is now complete and basically ready for a review. As there have been so many Boost.Process drafts before (after all the first version was created 2006) this library's version number is 0.4. This will somehow make it possible to refer to the various drafts if it's necessary. For now I would appreciate if the library's test cases are run on as many platforms as possible. After copying the files from the ZIP file to the Boost folder change to libs/process/test/ and run bjam - that's all! What has been changed? * All previous Boost.Process drafts including Ilya's 2008 version from the vault have been thoroughly studied to create a better version. From the multiple Boost.Process drafts which have been floating around since 2006 we took the best ideas and created a new unified version. * The design and implementation of the library have been simplified. The library's API is smaller, and the implementation is easier to understand. It should be possible to benefit from this library as quickly as possible. Even developers who have no experience in managing system processes should be able to do so easily. * There are no POSIX and Windows specific classes anymore (posix_context, posix_child, win32_context, win32_child etc. have been dropped). Instead of trying to support each and every feature platforms provide extension points have been defined. They enable library users to "link in" those platform specific features they are interested in. * For the first time there is full support for synchronous and asynchronous operations. While asynchronous operations are built on top of Boost.Asio synchronous operations can be utilized without that library. Developers don't need to include any Boost.Asio headers and don't need to learn about Boost.Asio if they don't need asynchronous operations. * Stream behaviors define if and how standard streams can be used by a child process. While the various stream behaviors were defined as an enumeration or a boost::variant in previous Boost.Process drafts they are now implemented as classes. This makes it possible for developers to create new stream behaviors. * The code to start child processes on POSIX platforms has been carefully adapted to support multi-threaded applications (it turned out that this code was wrong in all Boost.Process drafts so far). The documentation explains what you need to take care of if you want to create child processes in a multi-threaded application on POSIX platforms. * The documentation is new and has been shortened and simplified. There is a user guide which can be read in 10 minutes and introduces all the major features of the library. The documentation is now also based on Quickbook. * The test cases have been restructured to simplify them. They can now be run without patching Boost.Test and without setting a path to a helper executable in the source files - it's now all automatic. They are all passed successfully with MSVC 9 (2008) and g++ 4.2.1. What is currently missing? * Pipelines are not (yet) supported. If you have been using boost::process::launch_pipeline() there is nothing in this Boost.Process draft you can use instead. Depending on feedback this feature will be added again (there was simply no time yet to do this). We hope that after four years, two Google Summer of Code programs and countless drafts this new version will finally become the official Boost.Process library so many have been waiting for. Boris and Felipe

18 182

Thoughts for a GUI (Primitives) Library
by Gwenio 20 Oct '10

20 Oct '10

As it stands, neither Boost nor C++ has any support for GUI applications. Therefore I am suggesting a library that provides the bare minimum required to create a GUI application. My thoughts on what this library would contain are as follows: - Types for controls (contexts bound to the extent of their parent) and windows (contexts that remain separate from their parents). - An event handler class that is passed when controls and windows are created that contains all information needed to handle events for the new context. - Functions for generating events (if applicable) and (a) function(s) to initiate message handling (unless the event loop is run in its own thread like in Java). - Functions to access and manipulate the data of the contexts (size, position, z-order, ect). - Miscellaneous other types used for support (such as for screen positions). - A way to retrieve the native concept of a window/control. As you can see, there are no controls/widgets/ect defined, either from the library or using the native versions. Such things can be added later, if people can ever agree on how they should be implemented. It needs a lot of refining, but I believe this covers the *minimum* support that is needed for a GUI.

22 78

Re: [boost] [exception] ostringstream like
by Fabien Castan 19 Oct '10

19 Oct '10

> No, I mean that if you do advanced string manipulation in the exception > itself, you may screw up, adn cause a bad_alloc beign thrown and masking > your own exception. Create an error sentence with some values inside is not really an advanced string manipulation. You can have 2 kinds of errors: bug inside a custom operator<< or a memory problem. There is no particular reason to not have sufficient memory to create an error sentence when throwing something like a logic_error. > Just make your own, informative exception type deriving from logic_error. The problem is not really the kind of exception, but an easy way to create message with boost exception tag system. The idea is to create a new base class for tags allowing to use an ostringstream with tags, which is not possible. typedef ::boost::error_info<struct tag_message,std::ostringstream> message; This little class only remap operator+ call to operator<< on an internal ostringstream. typedef ::boost::error_info<struct tag_message,::boost::error_info_sstream> message; I use it in my code, but I ask here if we can hope to see such things in boost exception. I would prefer to use a standard boost object rather than a custom class.

4 3