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Boost Iterator: Limiting an existing iterator
by אנטולי קרס נר 03 Aug '13

03 Aug '13

Hello, I'm writing a C++ class which has an STL container as a data member, and I'd like to write an iterator class which allows to iterate through the container. Which container is used, is implementation detail. I want the iterator to be a ForwardIterator, even if a random-access container is used, e.g. std::vector. What's the quick and simple way to define an iterator adapter class which uses the "base" iterator's functions, but only the ones supported by a forward iterator? The reason I need it is error detection. If the user gets a random-access iterator and treats it as such, the compiler won't complain, but in future versions of my code the user's code may break because random access shouldn't really be supported, e.g. if I change from vector to list. Thanks in advance, fr33domlover Hmmm... I guess using boost::iterator_adapter should help

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[asio] using libgamin
by Alexander Nagel 03 Aug '13

03 Aug '13

Hello, one can use "signal_set" to connect to a SIGHUP signal and then reload a configuration file. I am thinking about a different approach. What about using libgamin to get notified if the config file changes and then reload automatically, if the config file is correct and valid. Is it possible to implement that behavior with asio? I read through the reference but I couldn't find something. I am not yet familiar with all aspects of asio. Perhaps I have overread it. Does anybody have a hint or an idea, please? regards, Alexander -- I would prefer to have encrypted communication. If you also prefer to encrypt emails, please do. Alexander Nagel Email: alexander(a)acwn.de Homepage: http://www.acwn.de/

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Boost Regex link errors with clang on Mac OS
by Rodrigo Madera 02 Aug '13

02 Aug '13

Linking with Boost Regex delivers this message: Undefined symbols for architecture x86_64: "boost::regex_error::regex_error(std::string const&, boost::regex_constants::error_type, long)", referenced from: boost::re_detail::basic_regex_creator<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::fixup_recursions(boost::re_detail::re_syntax_base*) in tools_utils.o boost::re_detail::basic_regex_creator<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::create_startmaps(boost::re_detail::re_syntax_base*) in tools_utils.o boost::re_detail::basic_regex_creator<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::create_startmap(boost::re_detail::re_syntax_base*, unsigned char*, unsigned int*, unsigned char) in tools_utils.o boost::re_detail::basic_regex_parser<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::fail(boost::regex_constants::error_type, long, std::string, long) in tools_utils.o "boost::re_detail::lookup_default_collate_name(std::string const&)", referenced from: boost::re_detail::cpp_regex_traits_implementation<char>::lookup_ collatename(char const*, char const*) const in tools_utils.o ld: symbol(s) not found for architecture x86_64 According to the Stack Overflow link [1], the problem lies in a clang bug. But I updated to the latest version I could find and it's still there. Apparently the BOOST_REGEX_NO_EXTERNAL_TEMPLATES define does work on preventing the hack on the template keyword, on boost/regex/v4/instances.hpp . Anyone else had this bug? Thanks for any help letting me compile without ugly hacks, Rodrigo I'm using Mac OS X 10.8.4, and compiling with C++11. > c++ --version Apple LLVM version 4.2 (clang-425.0.28) (based on LLVM 3.2svn) Target: x86_64-apple-darwin12.4.0 Thread model: posix References: [1] http://stackoverflow .com/questions/10879284/how-to-dynamically-build-and-link-boostregex -with-hidden-inlines

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[multi-index] retrieve unique keys of a non-unique index
by Rory McCarthy 02 Aug '13

02 Aug '13

Hi everyone (my apologies if this shows as a report), In the following example is there a more efficient way to retrieve the unique keys of a non-unique index? #include <boost/multi_index_container.hpp> #include <boost/multi_index/member.hpp> #include <boost/multi_index/hashed_index.hpp> #include <boost/tuple/tuple.hpp> #include <algorithm> #include <iostream> #include <iterator> #include <string> using boost::multi_index_container; using namespace boost::multi_index; struct name {}; struct value {}; struct guid {}; struct TaggedNodeEntry { int name; int value; std::string guid; TaggedNodeEntry(int name_, int value_, std::string guid_) : name(name_), value(value_), guid(guid_) {} friend std::ostream& operator<<(std::ostream& os, const TaggedNodeEntry& e) { os << e.name << " " << e.value << " " << e.guid; return os; } }; typedef multi_index_container< TaggedNodeEntry, indexed_by< hashed_non_unique< tag<name>, BOOST_MULTI_INDEX_MEMBER(TaggedNodeEntry, int, name) >, hashed_non_unique< tag<value>, BOOST_MULTI_INDEX_MEMBER(TaggedNodeEntry, int, value) >, hashed_non_unique< tag<guid>, BOOST_MULTI_INDEX_MEMBER(TaggedNodeEntry, std::string, guid) > > > TaggedNodes; int main() { TaggedNodes taggedNodes; taggedNodes.insert(TaggedNodeEntry(1, 1, "one-one")); taggedNodes.insert(TaggedNodeEntry(1, 2, "one-two")); taggedNodes.insert(TaggedNodeEntry(1, 3, "one-three")); taggedNodes.insert(TaggedNodeEntry(2, 1, "two-one")); taggedNodes.insert(TaggedNodeEntry(2, 2, "two-two")); taggedNodes.insert(TaggedNodeEntry(3, 6, "three-six")); std::cout << std::endl << "Unique names :-" << std::endl; boost::multi_index::index<TaggedNodes, name>::type::iterator ic0 = get<name>(taggedNodes).begin(); boost::multi_index::index<TaggedNodes, name>::type::iterator ic1 = get<name>(taggedNodes).end(); while (ic0 != ic1) { std::cout << ic0->name << std::endl; ic0 = get<name>(taggedNodes).equal_range(ic0->name).second; } return 0; }

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[Wave] Making wave driver work with 0 arguments passed as __VA_ARGS__
by Szymon Kurek 02 Aug '13

02 Aug '13

Hello everyone, I'm porting some g++ code to MSVC, and I'm trying to use the Boost.Wave driver executable as a preprocessor instead of Visual Studio's. Boost 1.54.0. I'm generally successful, but I'm having trouble with macros like these: #define LOG(msg, ...) whatever Usage examples: LOG("Hello world!"); LOG("Hello and print out some variables", foo, bar); Both g++ and MSVC have custom extensions that make these examples work, but Wave is pretty strict and follows the standard to the letter, so gives the error message "not enough arguments for macro LOG" for the first example. I know it's possible to rewrite each macro like this in a standard-compliant way, but it's a lot of work and gets complicated if I want recursive macro invocation. Is it possible to enable this behaviour in wave somehow? Do I need to compile Wave Driver with a specific option? I searched through the docs and tried looking at the code, but I can't find anything. Regards, Szymon Kurek

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[Interprocess] Page default
by Oodini 02 Aug '13

02 Aug '13

Hello, I use Boost.Interprocess on Windows 2003 Server. I am experiencing performances troubles. I am trying to understand what happens, and arrived on Microsoft web pages. I seems that on Windows, shared memory is implemented only through mapped files, and that only a portion of the shared memory is physically in the RAM (this limited number of pages is called "working set"). The Windows API provides some functions for this working set : http://msdn.microsoft.com/en-us/library/windows/desktop/cc441804%28v=vs.85%… I would have liked Interprocess wraps the functions GetProcessMemoryInfo() and SetProcessWorkingSetSize(), so that the full shared memory is put in RAM. But for now, I fear it is impossible to have with Interprocess performances similar to the ones provided by the alternative : data in the process memory.

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[boost::gil] Type conversion in Generic Image Library
by Nestor Morales Hernández 01 Aug '13

01 Aug '13

Hello, I'm a newbie in this library and I feel a little bit lost. I have the following problem: I currently have an image of the type ` boost::gil::rgb8c_view_t`. I need to pass it to a function (from a code I don't mantain) with this prototype: void function(const boost::gil::rgb8c_view_t& input, const int index, const boost::gil::rgb8c_view_t::view_t &output) I have created an output image by using the following syntax: boost::gil::rgb8c_view_t::view_t output(input._dynamic_cast<boost::gil::rgb8c_view_t::view_t>()); At this point, the compiler accepts the image output as input for the function. However, I need the image back to the `boost::gil::rgb8c_view_t` type. The question is: - Is it a correct way to allocate the image output? - How do I transform it back to the type boost::gil::rgb8c_view_t? Thank you in advance, Néstor

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[iostreams] How can I use the Stream Insertion operator (<<) with a filtering_streambuf?
by Stephen Greenfield 01 Aug '13

01 Aug '13

Partially asked in another question, but so far unanswered: Once I create a filtering_streambuf that is connected to the zlib_compressor() and the output file, how do I then construct an object that can accept data from the Stream Insertion Operator? void CompressUsingFilteringStreambuf() { std::ofstream myFile("hello.z", std::ios_base::out | std::ios_base::binary); boost::iostreams::filtering_streambuf<boost::iostreams::output> out; out.push(boost::iostreams::zlib_compressor()); out.push(myFile); // MY QUESTION: How can I use the "stream insertion" operator (<<) // to go through the filtering_streambuf // and place compressed text into myFile? // HOW DO I CREATE someStream? someStream << "text I want to be compressed and end up in the file..."; myFile.close(); } I have scoured the documentation and the web looking for the answer -- and come up empty. Stephen

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Using Boost-Log for real-time logging (windows)
by Gheorghe Marinca 01 Aug '13

01 Aug '13

Hi all, I want to use boost-log for "real time" logging. what I mean by that is a logging where one can enable/disable parts of the logging at runtime and is also has performance. We have used logging on windows based on ETW (Event tracing for Windows) that offers high performance and is dynamic. Can we use ETW based logging with boost-Log on windows ? Regards -Ghita

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[quickbook] Understanding xsl:param(s) for TOC generation
by legalize+jeeves＠mail.xmission.com 01 Aug '13

01 Aug '13

[Please do not mail me a copy of your followup] I have this magic recipe in my jam file: import quickbook ; boostbook foo : src/foo.qbk : <xsl:param>chunk.section.depth=4 <xsl:param>chunk.first.sections=1 <xsl:param>toc.section.depth=4 <xsl:param>toc.max.depth=4 <xsl:param>generate.section.toc.level=4 and to be honest I copy/pasted it from somewhere else and I really don't understand this recipe. I looked in the quickbook documentation and I couldn't find anything discussing these parameters like toc.max.depth, etc. Where can I find documentation on these paramters? -- "The Direct3D Graphics Pipeline" free book <http://tinyurl.com/d3d-pipeline> The Computer Graphics Museum <http://computergraphicsmuseum.org> The Terminals Wiki <http://terminals.classiccmp.org> Legalize Adulthood! (my blog) <http://legalizeadulthood.wordpress.com>

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