November 2009 - Boost - lists.preview.boost.org

Boost using MS Visual Studio 2010 - C2027
by Christofer Weßeling 04 Nov '09

04 Nov '09

Hi! I've tried to build Boost using MS Visual Studio 2010, but I'm getting a C2027 error. Basically the problem is known and located as a problem of the MS compiler: https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?Feedb… Is there still a workaround? Greets! Christofer Here comes the error....: 1>c:\projekte\boost\1.40.0\boost\bind\bind.hpp(1657): warning C4180: qualifier applied to function type has no meaning; ignored 1> c:\projekte\boost\1.40.0\boost\bind\bind.hpp(1691) : see reference to class template instantiation 'boost::_bi::add_cref<Pm,I>' being compiled 1> with 1> [ 1> Pm=FileTime<UTC> (__thiscall File::* )(void), 1> I=1 1> ] 1> c:\projekte\ps3controlmodule\productformattingasd\fileadmin.cpp(346) : see reference to class template instantiation 'boost::_bi::dm_result<Pm,A1>' being compiled 1> with 1> [ 1> Pm=FileTime<UTC> (__thiscall File::* )(void), 1> A1=boost::arg<1> 1> ] 1>c:\projekte\boost\1.40.0\boost\bind\bind.hpp(1691): error C2027: use of undefined type 'boost::_bi::add_cref<Pm,I>' 1> with 1> [ 1> Pm=FileTime<UTC> (File::* )(void), 1> I=1 1> ] 1> c:\projekte\ps3controlmodule\productformattingasd\fileadmin.cpp(347) : see reference to class template instantiation 'boost::_bi::dm_result<Pm,A1>' being compiled 1> with 1> [ 1> Pm=FileTime<UTC> (__thiscall File::* )(void), 1> A1=boost::arg<2> 1> ] 1> 1>Build FAILED.

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Build boot 1.40.0 on IBM z/OS (EBCDIC)
by norbert.hanke＠bluewin.ch 03 Nov '09

03 Nov '09

Hi folks, I am trying to build boost on the IBM Mainframe on z/OS USS. I successfully modified the jam bootstrap script and have a running bjam binary now. But when trying to build the boost libraries, I get the error below. Does anybody have a hint what to look for? EBCDIC character encoding on my machine might be the reason: digits 0-9 are encoded as character values 240-249, but I have no idea where to start looking. regards, Norbert > ./bjam /home/u250672/boost_1_40_0/tools/build/v2/util/numbers.jam:22: in numbers.check from module numbers error: 03 in 03 1 17 error: is not a number /home/u250672/boost_1_40_0/tools/build/v2/build/version.jam:50: in version-less from module version /home/u250672/boost_1_40_0/tools/build/v2/build/version.jam:102: in version.check-jam-version from module version /home/u250672/boost_1_40_0/tools/build/v2/util/path.jam:172: in join from module path /home/u250672/boost_1_40_0/tools/build/v2/util/path.jam:207: in path.root from module path /home/u250672/boost_1_40_0/tools/build/v2/util/path.jam:247: in path.glob from module path /home/u250672/boost_1_40_0/tools/build/v2/tools/types/register.jam:25: in load from module types/register /home/u250672/boost_1_40_0/tools/build/v2/kernel/modules.jam:283: in import from module modules /home/u250672/boost_1_40_0/tools/build/v2/tools/stage.jam:19: in load from module stage /home/u250672/boost_1_40_0/tools/build/v2/kernel/modules.jam:283: in import from module modules /home/u250672/boost_1_40_0/tools/build/v2/tools/builtin.jam:25: in load from module builtin /home/u250672/boost_1_40_0/tools/build/v2/kernel/modules.jam:283: in import from module modules /home/u250672/boost_1_40_0/tools/build/v2/build-system.jam:11: in load from module build-system /home/u250672/boost_1_40_0/tools/build/v2/kernel/modules.jam:283: in import from module modules /home/u250672/boost_1_40_0/tools/build/v2/kernel/bootstrap.jam:138: in boost-build from module /home/u250672/boost_1_40_0/boost-build.jam:16: in module scope from module

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Temporary objects
by DE 03 Nov '09

03 Nov '09

hi all unfortunately i'm totally out of time now so i only write my proposal and an example forgive me for that the code #include <algorithm> template<typename type> class temporary : public type { temporary() : type() {} temporary(temporary &a) : type() { using std::swap; swap(static_cast<type&>(*this), static_cast<type&>(a)); } template<typename other> temporary(const other &a) : type(a) {} temporary &operator=(temporary &a) { using std::swap; swap(static_cast<type&>(*this), static_cast<type&>(a)); return *this; } template<typename other> temporary &operator=(const other &a) { type::operator=(a); return *this; } }; example1 temporary<huge_type> foo(const huge_type &a) {//returning temporary object temporary<huge_type> ret; //or even 'ret(a)' //doing something... return ret; } //... huge_type result; result = foo(bar); //somewhere in code only one copy operation -- assignment operator return by value copying overhead is eliminated with help of swap() example2 struct my_type { //... my_type(temporary<my_type> &a) { this->swap(a); } //... my_type &operator=(temporary<my_type> &a) { this->swap(a); return *this; } //... }; temporary<my_type> process(const my_type &item) { temporary<my_type> ret; //processing item... return ret; } //... my_type result = process(item); //somewhere in code //or result = process(item); no temporary object handling overhead at all return by value, copy-construct and assign from temporary objects for free! thank you for attention

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[interval container (itl)] A pretty large bitset
by Joachim Faulhaber 03 Nov '09

03 Nov '09

Dear list! In thread http://lists.boost.org/Archives/boost/2009/06/152786.php Zachary Turner posted an article about a compressed bitset, that uses run-length defined intervals to achieve a compact representation of large bitsets that are useful for managing huge file allocation tables. As I mentioned in a reply to this article, Zach's compressed bitsets, in their basic ideas, are quite similar to itl::interval_sets: They allow for compression of large quantities of elements as long as they occur in (large) uninterrupted chunks. As Zach pointed out, this nice behavior is completely spoiled, if we would want to handle a set like {1,3,5,7,9,...,2(k-1)} or as bitset '0101010101...01' Here, the capability of usual bitsets to compress elements that are distributed over only small ranges can neither be applied to Zach's compressed bitset nor to an itl::interval_set of the Interval Template Library. As a new use case of interval containers I have developed a *large_bitset* class template on top of itl::interval_map that is able to combine interval compression *and* bitset compression. It is, for instance, capable of representing the bitset mentioned above '01010101...010' a b a: bit 0 b: bit 2^64-1 containing 2^63 bits (or elements) with just *one* internal interval associated to only *one* value of 64bit length ;) Curious?? Find the documented example code in my updated library docs at http://www.herold-faulhaber.de/boost_itl/doc/libs/itl/doc/html/boost_itl/pr… While the documented class template 'large_bitset', for reasons of a short presentation, is only a minimal one, you can find a more elaborated version as 'interval_bitset' in the sandbox at https://svn.boost.org/svn/boost/sandbox/itl/boost/itl_xt/interval_bitset.hpp I'd like to ask Zachary Turner to comment on the use case. Can this be useful in your field? Moreover I'd like to encourage everyone to give feedback on my interval container library, report problems, bugs and share suggestions. If you find this stuff useful please volunteer as review manager for the submitted library Boost Interval Containers. Note, that the new example on 'large_bitsets' is not yet included in the library submitted for review in the vault but it is contained in the sandbox. I am currently preparing an update of the review version of the itl, that is adjusted and corrected for the feedback, suggestions and patches that I have received during the last weeks. I will integrate further feedback and account for bug reports if you have any. Best regards Joachim

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[tree?] STL like tree data structure in boost?
by Nil Geisweiller 03 Nov '09

03 Nov '09

hi, any idea if there is in boost a similar tree data structure such as Kasper Peeters's tree.hh http://tree.phi-sci.com/ ? thanks Nil

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Parallel Tree Merge
by Biddiscombe, John A. 03 Nov '09

03 Nov '09

If I have a representation of a tree and I have sub-portions of it spread across a number of processes (but the whole tree represents a well-formed and simple tree structure). Is there a reasonably straightforward way of doing this using BGL or PBGL. I had hoped that it might be as simple as defining some templated tree structure and using the add operator after gathering pieces onto one node. (The tree structure could be represented as XML where the root would exist on all processes, different sub-nodes and leaves and would occur on different processes - a simple xml merge would probably suffice for my needs right now). If examples using boost libraries ((p)BGL/MPI) or other similar combination exist and anyone can point me to resources I'd be most grateful. (I'm not an expert with BGL so will need some do some learning...) Thanks JB -- John Biddiscombe, email:biddisco @ cscs.ch http://www.cscs.ch/ CSCS, Swiss National Supercomputing Centre | Tel: +41 (91) 610.82.07 Via Cantonale, 6928 Manno, Switzerland | Fax: +41 (91) 610.82.82

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Cross-platform date/time problems
by Zachary Turner 03 Nov '09

03 Nov '09

Hello list, Apologies for the cross-posting, this originally went to the boost-users list but it got no responses, and then I also realized it was actually more appropriate here. Suppose I have a cross-platform agent that communicates with a server. Agent from platform X sends a message to the server which contains a date/time. Server sends a message to another agent running platform Y with the same date/time. In practice X/Y are always either windows/linux or linux/windows. The server always tells the agent which platform's native format the time is represented in, so there should be no problem. Ideally I'd like to write the following code: ptime time; if (msg.is_from_windows()) { time = from_ftime<ptime>(msg.time()); } else { time = from_time_t(msg.time()); } But this doesn't work because from_ftime<> is not defined on linux. If from_ftime<> is already templated on the FILETIME type, is there any reason it needs to be #ifdef'd out on non-windows platforms? I mean, a FILETIME is really just a uint64, can't the templated function also just operate on a boost::uint64_t? Zach

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#3541 Support <boost/ptr_map.hpp>
by Olaf van der Spek 02 Nov '09

02 Nov '09

Hi, https://svn.boost.org/trac/boost/ticket/3541 Could a forward header file be created such that #include <boost/ptr_map.hpp> works? The extra ptr_container directory is hard to remember..., I always have to look it up. boost/ptr_* looks much more natural. Greetings, Olaf

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Re: [boost] loglite - A logging library (JD) (Zachary Turner)
by Tan, Tom (Shanghai) 02 Nov '09

02 Nov '09

>I've always found it was easiest to do something like: >namespace boost { namespace filesystem { >#if defined(_WIN32) || defined(WIN64) > typedef wpath npath; >#else > typedef path npath; >#endif >} } >and then use boost::filesystem::npath everywhere. Performance isn't >generally the bottleneck when dealing with the filesystem, but why even >bother with so many behind-the-scenes conversions when you can just as >easily store everything in the type the O/S is expecting in the first place >with a simple typedef? That's handy when only OS API is involved, but if you have to use it other Libraries which are only string-ready, e.g. LIGLITE, you have no choice. Even Some popular Boost libraries are only for strings, Boost.Test is one.

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The C++ Post-Processor
by Christian Schladetsch 02 Nov '09

02 Nov '09

Hello, This is a general post about C++. Why is it that the pre-processor (PP) is the source of so much disdain, and yet it is the first resource exploited to 'fix' problems with C++? Why has the PP received so little attention over the years, from its early use as M4? This is a message to the powers that be: the PP is a powerful tool. It provides a 'context-cutting' mechanism for creating and extending solutions. It is a true "meta-programming" system built right into C++. No other language I can think of has a PP. This is often viewed as being a good thing, but I wonder more and more as I get older that a good PP is in fact needed to span some otherwise very difficult boundaries. Other languages are "dynamic" inasmuch as they reflect classes and allow for runtime changes to types and instances. I think we all here agree that this ability is counter to building firm, safe and efficient software. But the PP is similar to that, allowing a degree of dynamicy not otherwise available. Specifically, by exposing concepts to the PP we can leverage reflection and synthesis while building on inheritance and conglomeration. I don't have a point as such; I just wanted to raise the idea of developing M4 and the PP past where it is. There is a lot of low-hanging fruit there. This is evidenced by the fact that a lot of other languages are or can be transliterated to C++. Rather than thinking of C++ as the output, we could be thinking of C++ as the input. Perhaps a way forward for C++ is a good PP and a standards-based implementation of C++ in C++ so it can embed itself. I've written a number of languages, and in each I've had to address the issue of pre-processing. The latest attempts have resulted in a system where it parses and executes via AST input to produce an output that is then parsed by the same system to produce an AST that is then walked to eventually produce machine code. I think this model is best, and would be delighted to see some similar movements in the PP/C++. We have Boost.Wave to start with... Why not give it real Expressions? Loops? Scopes? Classes? Templates? memory management? IO? Is there any interest in a Boost.C++ ? Regards, Christian

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