March 2006 - Boost - lists.preview.boost.org

[off-topic] why do we not have std::copy_if?
by Caleb Epstein 14 Mar '06

14 Mar '06

I've recently wondered why std::copy doesn't have an analogous std::copy_if: template<class InIt, class OutIt, class Pr> OutIt *copy_if*(InIt first, InIt last, OutIt dest, Pr pred); that would copy elements to dest where the predicate returns true. Not unlike "grep" in Perl and "filter" in Python. The same goal can be achieved with std::remove_copy_if and the use of a sense-reversed predicate, but this leads to confusing code IMHO. Why wouldn't this be part of the Standard Library, or am I missing something ridiculously obvious? -- Caleb Epstein caleb dot epstein at gmail dot com

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no matching function for call to boost::algorithm::split
by Olaf van der Spek 14 Mar '06

14 Mar '06

Hi, I'm trying to compile the following code with g++, but it generates an error. It compiles fine in VC8. typedef vector<string> to_t; to_t to; split(to, row.f(2).s(), is_any_of(",")); error: no matching function for call to 'split(main()::to_t&, std::string, boost::algorithm::detail::is_any_ofF<char>)' /usr/include/boost/algorithm/string/split.hpp:143: note: candidates are: SequenceSequenceT& boost::algorithm::split(SequenceSequenceT&, RangeT&, PredicateT, boost::algorithm::token_compress_mode_type) [with SequenceSequenceT = main()::to_t, RangeT = std::string, PredicateT = boost::algorithm::detail::is_any_ofF<char>] Does anyone know what I'm doing wrong? $ g++ -v Using built-in specs. Target: i486-linux-gnu Configured with: ../src/configure -v --enable-languages=c,c++,java,fortran,objc,obj-c++,ada,treelang --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --program-suffix=-4.1 --enable-__cxa_atexit --enable-clocale=gnu --enable-libstdcxx-debug --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-4.1-1.4.2.0/jre --enable-mpfr --with-tune=i686 --enable-checking=release i486-linux-gnu Thread model: posix gcc version 4.1.0 20060127 (prerelease)

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[spirit] ast_calc_tests, repeast_ast_tests
by Vladimir Prus 14 Mar '06

14 Mar '06

Hi, the above two tests fail on a number of compilers with what looks like a two-phase lookup issue. See: http://tinyurl.com/jeakp http://tinyurl.com/q3hbv I can reproduce this locally with g++ 3.4. Can somebody check if this is a bug in the library, or some quirk with g++ 3.4? Thanks, Volodya

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Hello
by jsiek＠osl.iu.edu 14 Mar '06

14 Mar '06

Mail transaction failed. Partial message is available.

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C++ and XML Data Binding
by Agarwal, Abhishek 14 Mar '06

14 Mar '06

Hello, I was wondering if BOOST currently has any XML data binding library. Any comments? Thanks, Abhi

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[app submission] Paragent Manage
by Timothy Ritchey 14 Mar '06

14 Mar '06

Application: Paragent Manage 2.1 Company: Paragent URL: <http://www.paragent.com> Description: Paragent Manage is a Desktop Management Application that uses a lightweight agent written in C++. Unlike traditional desktop management solutions, Paragent Manage avoids the complexity and cost of servers by using peer-to-peer communication between agents and the administrative console. This allows real-time inventory searching, alerting and software auditing in an easy-to-deploy and maintain package. Boost Usage: We have used boost extensively throughout our agent, including: threads shared_ptr bind spirit date_time algorithm multi_index filesystem Apart from some read_write_mutex issues we had, boost has been a seamless part of our development, and has allowed us to develop and deploy a very complex, highly threaded networking agent with a built-in lisp-like xml-based scripting language all done in C++. Our entire development team would like to thank everyone for their hard work on behalf of C++ coders everywhere.

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[xpressive] OSL2-V2 test failures
by Vladimir Prus 14 Mar '06

14 Mar '06

Doug, in the current OSL2-V2 results, many of xpressive tests fail at runtime with some dynamic linking error: http://tinyurl.com/q62ly The error basically says that 3.4.4 binary links to runtime from another gcc version. I have no idea why it shows up on one test, but I'd need your help to solve this. Can you do this: 1. Given me the exact content of toolset files you use for V1 (not V2) testing. 2. Give me the content of user-config.jam 3. Go to libs/xpressive/test, touch c_traits.cpp and then run the "c_traits" test using -n option with both V1 and V2 and with both compiler version. I think that the following commands should work bjam -n -sTOOLS=gcc-3.3.6-linux c_traits bjam -n -sTOOLS=gcc-3.4.4-linux c_traits bjam -n --v2 gcc-3.3.6 c_traits bjam -n --v2 gcc-3.4.4 c_traits and send me the output. Thanks in advance, Volodya

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[statechart] gcc-patches
by Juergen Hunold 14 Mar '06

14 Mar '06

Hi Andreas ! I've tried to run the statechart examples and tests with gcc 4.0 using Boost.Build V2. The attached patch corrects some minor glitches: The examples don't run from the "run" directory because gcc's -rpath option is not used when using shared libraries. This is enabled by <hardcode-dll-paths>true The test Jamfile produces *tons* of warnings because -Wno--non-virtual-dtor is not set and detail/rtti_policy has an (empty) virtual function named "dummy" but no virtual destructor. I simply disabled this warning, but I'm not happy about it. It has been helpful in my own code in the past. Is there any chance to make the destructor virtual when a vtable is needed ? Yours, Jürgen -- * Dipl.-Math. Jürgen Hunold ! Ingenieurgesellschaft für * voice: ++49 511 262926 57 ! Verkehrs- und Eisenbahnwesen mbH * fax : ++49 511 262926 99 ! Lister Straße 15 * hunold(a)ive-mbh.de ! www.ive-mbh.de

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[test] gcc-warnings patch
by Juergen Hunold 14 Mar '06

14 Mar '06

Hi ! The attached patch fixes the following annoying gcc-Warnings: --- snip ------- boost/test/test_observer.hpp:38: warning: unused parameter 'test_cases_amount' /boost/test/test_observer.hpp:43: warning: unused parameter 'elapsed' boost/test/test_observer.hpp:47: warning: unused parameter 'passed' --- snap ------- And "boost/test/included/unit_test_framework.hpp" is missing a newline at EOF. I found those glitches because I compile with Boost.Build V2 which has -W -Wall as default for the gcc toolset. Yours, Jürgen -- * Dipl.-Math. Jürgen Hunold ! Ingenieurgesellschaft für * voice: ++49 511 262926 57 ! Verkehrs- und Eisenbahnwesen mbH * fax : ++49 511 262926 99 ! Lister Straße 15 * hunold(a)ive-mbh.de ! www.ive-mbh.de

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lambda and typeof, finally an effective in-place arithmetic metafunction generator.
by pongba 14 Mar '06

14 Mar '06

Okay, just image some sort of code like this: typedef mpl::vector_c<int,1,2,3> v; typedef mpl::accumulate<v,int_<0>,MPL_METAFUNC(_1*CONS(10)+_2)>::type::value result_value; // =123 Imaginably, the implementation of MPL_METAFUNC would involve BOOST_TYPEOF to deduce the type of "_1*CONS(10)+_2" so as to construct a corresponding metafunction, that is, "mpl::plus<_2,mpl::times<_1,int_<10> > >" (CONS here is used to work around the embarrassment that 10 becomes sort of variable when passed directly to operator*, so we use CONS(10) which expands into something like "int_<10>()" which entirely preserve "10" at compile-time). Arguably this is feasible, but I lack the time to implement it fully. (although it would be pretty simple, e.g. #define DEFINE_BINARY_OP(op,mpl_binray_op) \ template <typename T, typename U> \ mpl_binary_op<T,U> operator op (T t, U u) \ { \ return mpl_binary_op<T,U>(); \ } \ DEFINE_OP(+,mpl::plus) DEFINE_OP(-,mpl::minus) DEFINE_OP(*,mpl::times) DEFINE_OP(/,mpl::divide) ... Admittedly, there exists a name confliction between mpl::_1 and lambda::_1 due to the inherent difference between type and variable in the language, so we couldn't use the same _1 and _2 in both "plus<_1,_2>" and "_1+_2". Any good remedies for that?(of course we could always turn to "_1()+_2()" in which _1/2 means mpl::_1/2) My question is: Is this valuable?(IMO,it'll make arithmetic operation in metaprogramming much easier and clearer, just watch "_1*10+_2" v.s. "mpl::plus<_2,mpl::times<_1,int_<10> > >" you'll see that). And if it is, would Dave consider adding it to MPL? Thanks in advance! -- Regards!

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