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

[function] Defect or feature?
by Germán Diago 09 Nov '09

09 Nov '09

Hello. I think this code should work (or convince me why not): #include <boost/function.hpp> class A {}; class B : public A {}; typedef boost::function<void (A &)> F; void hello(B &) { } int main() { F f(&hello); } Since A & can accept Bs &, should this code work?

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rule.ipp(173) : error C1128: number of sections exceeded object file format limit : compile with /bigobj
by HT4N - 09 Nov '09

09 Nov '09

I have quite a big grammar now, and basically I have multiple grammars separated into many files and at the root grammar I have many alternations like the following: Root = GrammarA | GrammarB ... | GrammarZ It looks like, the compiler complaining about the size of the inline code. Here is the error message from the compiler: "boost\spirit\core\non_terminal\impl\rule.ipp(173) : error C1128: number of sections exceeded object file format limit : compile with /bigobj" What is the solution to this issue? If I move the grammar definition to .cpp files will it help? Thanks HTan _________________________________________________________________ Windows 7: Unclutter your desktop. http://go.microsoft.com/?linkid=9690331&ocid=PID24727::T:WLMTAGL:ON:WL:en-U…

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What is the equivalent of pt_parse() in Spirit 2.1
by HT4N - 09 Nov '09

09 Nov '09

I want to be able to generate ParseTree and dump it into xml like in Spirit Classic. In the Classic we call pt_parse() which return tree_parse_info and we can dump it into XML easily using tree_to_xml(). Do we have the same functionality in Spirit 2.1? Thanks HT _________________________________________________________________ Windows 7: Unclutter your desktop. http://go.microsoft.com/?linkid=9690331&ocid=PID24727::T:WLMTAGL:ON:WL:en-U…

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program_options and wstrings
by Yang Zhang 09 Nov '09

09 Nov '09

I had some questions about using program_options with wstrings. I'm a bit confused after reading the documentation: http://www.boost.org/doc/libs/1_40_0/doc/html/program_options/howto.html#id… http://www.boost.org/doc/libs/1_40_0/doc/html/program_options/design.html#p… Excerpt: """ - Each parser should accept either char* or wchar_t*, correctly split the input into option names and option values and return the data. - For each option, it should be possible to specify whether the conversion from string to value uses ascii or Unicode. - The library guarantees that (1) ascii input is passed to an ascii value without change, (2) Unicode input is passed to a Unicode value without change, and (3) ascii input passed to a Unicode value, and Unicode input passed to an ascii value will be converted using a codecvt facet (which may be specified by the user). """ Bullet 1 tells me the system takes both char* and wchar_t*. Bullet 2 tells me that each option can request the string it's handed to be first coerced as either a char* or wchar_t*. This is the only char/wchar_t conversion that happens in the system (codecvt). Why, then, can't I say value<wstring> (besides wvalue<wstring>)? And why do I need to specify command_line_parser vs. wcommand_line_parser? The complexity stems from the fact that there seem to be three sets of variables in the code: - value vs. wvalue - [w]value<string> vs. [w]value<wstring> - command_line_parser vs. wcommand_line_parser I find it unclear what the consequences are of setting each of these one way vs. the other. Any explanations? Related: I ran into this bug: http://lists.boost.org/boost-users/2008/02/34016.php https://svn.boost.org/trac/boost/ticket/1645 Why does this happen? -- Yang Zhang http://www.mit.edu/~y_z/

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program_options positional and required arguments
by Yang Zhang 09 Nov '09

09 Nov '09

More usability issues with program_options: I couldn't really find much mention of positional options in the docs. I'm writing a typical command line program: one that takes some set of optional options and a single required positional argument. Currently, I'm doing (where namespace po = boost::program_options): po::options_description desc("Allowed options"); desc.add_options() ("help,h", "show this help message") ... ("exe", po::wvalue<vector<wstring> >(), "the command line to execute"); po::positional_options_description posopts; posopts.add("exe", -1); po::variables_map vm; po::store(po::wcommand_line_parser(argc, argv). options(desc).positional(posopts).run(), vm); po::notify(vm); if (vm.count("help") > 0) { cout << desc << endl; return 0; } ... if (vm.count("exe") == 0) { cerr << desc << endl; return 1; } wstring exe(vm["exe"].as<vector<wstring> >()[0]); I had to add the exe option to the regular (non-positional) options_description as a vector<wstring>, causing it to show up as an option in the usage message. Omitting it resulted in errors about the option being unregistered (even after trying to add allow_unregistered). Why would I get this error? Shouldn't the wcommand_line_parser::run method be doing this checking after it has collected all the sets of option descriptions? Can I get rid of this? What's the proper way to express what I want? Is there a way to require the positional argument occur (1) at least once and (2) at most once (besides manual checks after parsing)? The configuration of positional options doesn't seem to be quite as rich as those for normal options; is this accurate? Thanks. -- Yang Zhang http://www.mit.edu/~y_z/

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program_options hierarchical options
by Yang Zhang 09 Nov '09

09 Nov '09

Is there an example of using program_options to build a hierarchical options parser (a la svn, apt-get, git, etc.), in which earlier options select parsers for later options? -- Yang Zhang http://www.mit.edu/~y_z/

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[interprocess] Performance problem with managed_shared_memory
by Moritz 09 Nov '09

09 Nov '09

Hi there, I have a performance problem using the managed_shared_memory and the interprocess_vector. I attached a minimalistic, compilable example that demonstrates this. I create a vector that contains a simple class and I write into this vector. If the vector is located in the shared_memory this takes much longer than if it is located in the process-local memory. The main difference then is the used allocator. But I can not explain it. If I run the attached code, I get the following results: (running on Ubuntu 8.10, Boost version 1.40, gcc-Version 4.3.3) SHMEM_TESTING: Mean: 0.024768 seconds. else Mean: 0.015022 seconds. I do not understand where the difference results from. Is there anybody who has an explanation for that? #include <boost/interprocess/containers/vector.hpp> #include <boost/interprocess/allocators/allocator.hpp> #include <boost/interprocess/managed_shared_memory.hpp> #include <boost/thread/xtime.hpp> #include <iostream> #include <vector> namespace ipc = boost::interprocess; double get_timestamp() { boost::xtime timestamp; boost::xtime_get(&timestamp, boost::TIME_UTC); return timestamp.sec + ((double)timestamp.nsec / 1000000000.0); } class Point3f { public: double x; double y; double z; }; #define VECTOR_ELEMENTS 500000 int main() { #define SHMEM_TESTING #ifdef SHMEM_TESTING ipc::shared_memory_object::remove("shmem"); ipc::managed_shared_memory managed_shm( ipc::create_only, "shmem" , VECTOR_ELEMENTS*3*sizeof( double ) + 1024 ); typedef ipc::managed_shared_memory::segment_manager segment_manager_t; typedef ipc::allocator<void, segment_manager_t> void_allocator; typedef ipc::allocator<Point3f, segment_manager_t> Point3fAllocator; typedef ipc::vector<Point3f, Point3fAllocator> Point3fVector; void_allocator alloc( managed_shm.get_segment_manager() ); Point3fVector * vec = managed_shm.construct<Point3fVector>( ipc::unique_instance )( alloc ); if ( !vec ) return -1; #else ipc::vector<Point3f> * vec = new ipc::vector<Point3f>(); // std::vector<Point3f> * vec = new std::vector<Point3f>(); #endif for ( unsigned int i = 0; i < VECTOR_ELEMENTS; ++i ) { vec->push_back( Point3f() ); } double sum = 0; unsigned int count = 0; for ( ; count < 20; ++count ) { double t1 = get_timestamp(); for ( unsigned int i = 0; i < vec->size(); ++i ) { ( *vec )[i].x = i; ( *vec )[i].y = i; ( *vec )[i].z = i; } sum += get_timestamp() - t1; } std::cerr << std::fixed << "Mean: " << sum/static_cast<double>(count) << " seconds." << std::endl; return 0; }

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Re: [Boost-users] boost thread on x64
by Pascal Kesseli 08 Nov '09

08 Nov '09

Hi again In another attempt to compile my code using boost-thread headers, unfortunately none of the suggested preprocessor definitions worked. Does anyone see a possibility to make boost mingw64 compatible? Thx and best regards Pascal

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Avoiding reinventing the wheel for a public api with binary compatibility in mind
by Geoff Hilton 08 Nov '09

08 Nov '09

I'm writing a public api for a product which will be bundled as a precompiled dll or binary and one of my goals is binary compatibility (if not across major versions, at least across minor). I'd like to implement the pimpl idiom and reference counting for the handle classes as appropriate, but I'm worried about all the typical stuff (exception safety, memory leaks, etc) and I'd rather not reinvent the wheel. eg. template<typename T> class MyClass { public: T foo(); private: boost::shared_ptr<MyClassImpl<T> > impl; }; Using boost::shared_ptr would be great, but this means clients of my code would have to have the same version of boost installed that we use, and I imagine this could cause conflicts in the event that they happen to use boost (and a different version of it). I'd rather not include more code dependencies than I absolutely have to, especially if they may prove problematic in the future. What do I do? I know I'm not the first in this situation. How often have others opted for this dependency as opposed to furnishing their own alternative that would avoid additional dependencies (at the expense of the benefit of time-tested code)?

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[variant] Length of variant
by Seweryn Habdank-Wojewódzki 08 Nov '09

08 Nov '09

Hi, According to Karlsson boost::variant is limited to 11 elements. Is there any option to extend that? What are the real limitations for the VS 9.0 and GCC 4.0? If number might be extended what might happen e.g. during compilation? Is the size somewhere defined once or is spread in all the code of variant? Best regards, Seweryn Habdank-Wojewodzki.

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ASIO or Thread
by Lloyd 08 Nov '09

08 Nov '09

Hi, We need to develop a server in a LAN environment, in which the number of connections at a time will be less, but the data traffic per connection will be huge (gigabytes). So for the best performance which library is better? ASIO or Thread? Is thre is any specif advice for attaining the maximum performace (data rate)? I am a newbie. Thanks, Lloyd ______________________________________ Scanned and protected by Email scanner

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tons of errors because boost::thread::thread() in thread/detail/thread.hpp is private
by tiredashell 08 Nov '09

08 Nov '09

I am successfully using Boost.Thread on Windows without a hitch, but when porting my program to OSX I get the following compile error, followed by an enormous chain of errors that probably are a derivative of it: ./boost/thread/detail/thread.hpp:108: error: ‘boost::thread::thread(boost::thread&)’ is private When checking the class that it mentioned, it appears that it is in fact declared as private for some reason. Is there a reason I'm only receiving this error on OSX, and how can it be fixed?

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[Boost Asio] Newtork Programming
by Boost lzw 08 Nov '09

08 Nov '09

Folks, I want to start learning network programming + socket programming so that I can understand Boost.Asio and beyond it. Any good books for beginners or online resources to recommend? I have MSVS 2008 Profssional on Windows XP Professional installed on my PC. Thanks in advance, Robert

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Building Boost on Snow Leopard (with Xcode 3.2 installed)
by Manfred Schwind 07 Nov '09

07 Nov '09

Hi, I'm trying to build boost 1.40 on Mac OS X 10.6 Snow Leopard (with Xcode 3.2 is installed). This is the command I used to use on Mac OS X 10.5 Leopard and Xcode 3.1.x: bjam --prefix=/somepath --layout=versioned toolset=darwin architecture=combined address-model=32_64 link=static install This used to give me great universal binaries (ppc/intel, 32-/64-bit). But since installing Snow Leopard and Xcode 3.2 it does not build anymore. No binaries are created and I get strange compiler errors like this: /usr/include/time.h:77: error: expected constructor, destructor, or type conversion before ‘typedef’ /usr/include/time.h:124: error: ‘clock_t’ does not name a type In file included from /usr/include/c++/4.2.1/cwchar:52, from /usr/include/c++/4.2.1/bits/postypes.h:46, from /usr/include/c++/4.2.1/iosfwd:49, from /usr/include/c++/4.2.1/bits/stl_algobase.h:70, from /usr/include/c++/4.2.1/bits/char_traits.h:46, from /usr/include/c++/4.2.1/string:47, from ./boost/program_options/errors.hpp:12, from ./boost/program_options/options_description.hpp: 12, from libs/program_options/src/ options_description.cpp:10: I _assume_ the problem is gcc 4.2 that was probably installed by Xcode 3.2. I am also not sure if gcc 4.2 even supports PCC code generation. So is there a way to switch to gcc 4.0? Or any other solution for the problem? I tried toolset=gcc-4.0 instead of darwin. This resulted in some binaries, but they are not universal anymore, as far as I can see. Any ideas/hints how to successfully build boost on Snow Leopard? Thank you very much, Mani -- http://mani.de - friendly software iVolume - listen to music freehand LittleSecrets - the encrypted notepad Sahara - sand in your pocket Watchdog - baffle the curious

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Library failing
by Mathew Benson 07 Nov '09

07 Nov '09

I wrote a utility to abstract sending a data buffer to a central server with a single function call. I verified it works, and then split out the functionality into a library (.lib). I tried using it in a test application, but keep getting an "Access violation reading location 0x00000000" error. It occurs in the call: socket_.async_receive_from( boost::asio::buffer(data_, max_length), sender_endpoint_, boost::bind(&CommIn::handle_receive_from, this, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred)); I'm using Visual C++ 2005 Express, and a UML to C++ modeler and code generator called Rhapsody. I'm not sure where to even begin troubleshooting this.

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[program_options] multiple_occurrences exception
by Sam Miller 07 Nov '09

07 Nov '09

Is there a way to determine which option triggers the multiple_occurences exception to be thrown when calling program_options::store? As an example I have a component that takes a positional --exe argument. It would be nice to know when the exception is throw if --exe had been specified earlier in the command line. Thanks, Sam

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[serialization] Serializing const* to serialized data
by Noah Roberts 07 Nov '09

07 Nov '09

Consider something like so: struct A { ...? }; struct B { std::list<A> items; }; struct C { A const* ptr_to_item_in_B_items; }; Serializing B is easy. Serialization of C ... not so much. The naive approach did not work because it wants a non-const pointer. Having read posts about the problem it seems the serialization library expects to modify the data pointed to, but I don't need or want that...I just want to recover the structure layout. Possible? Impossible?

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Slicing multi_array
by James Amundson 06 Nov '09

06 Nov '09

Hi, I want to write a function that operates on one-dimensional multi_array's and use it to modify the columns of a two-dimensional multi_array. I thought that this would be a straightforward application of slicing, i.e., views with dimensional reduction. However, my first attempt to do so does not compile. (Please see the attached source code.) When I try to pass a view to my function, I get: error: invalid initialization of non-const reference of type boost::multi_array_ref<double, 1ul>& from a temporary of type boost::detail::multi_array::multi_array_view<double, 1ul> I have now read the section on views and subarrays in the multi_array reference documentation several times, but I do not see how I can do what I want. Any suggestions? Thanks, Jim Amundson

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[ASIO]what's the meaning of CompletionCondition in boost::asio::async_read?
by zong jinliang 06 Nov '09

06 Nov '09

dears, in function: void async_read<file:///F:/boost_1_40_0/doc/html/boost_asio/reference/async_read/overload2.html> (AsyncReadStream & s,const MutableBufferSequence & buffers, CompletionCondition completion_condition,ReadHandler handler); I am puzzled for the variant: "CompletionCondition completion_condition". take follow code as example: boost::asio::async_read(socket_,boost::asio::buffer(...),boost::asio::transfer_at_least(1),boost::bind(...)); Before I think it'll return if read 1 bit, but at fact it return until receive EOF or buffer is full. So why need this variant? It can return when receive EOF or buffer is full if there is no this varant, just like: boost::asio::async_read(socket_,boost::asio::buffer(...),boost::bind(...));

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Re: [Boost-users] [date_time] obtaining the current time
by Eric J. Holtman 06 Nov '09

06 Nov '09

Sean Farrow wrote: > > Hi: > > I need to obtain the users current local time in the users current > time zone. > > How would I go about doing this. Using a window operating system and > visual studio 2008. > boost::posix_time::microsec_clock::local_time();

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Get "Native" thread id - feature request
by Ondrej Sluciak 06 Nov '09

06 Nov '09

Hello, is there a way how to get the thread id that system assigns to thread? I mean the id that is located in "thread_info->id". It would quite nice if boost could return this value, because for example if I want to set name of the thread on windows using function SetThreadName(), I need exactly that id. In my application I would have to add this "feature" directly to boost::thread.hpp, which is not very nice solution. I know that also GetThreadName(myThread->native_handle()) should work, but if I do it like this I always get a Windows error "The procedure entry point GetThreadId could not be located in the dynamic link library KERNEL32.dll". And I also guess, that this new "feature" wouldn't destroy the overall design of boost::thread architecture. To get the "real" thread id is in my opinion in general a useful thing.

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[date_time] obtaining the current time
by Sean Farrow 06 Nov '09

06 Nov '09

Hi: I need to obtain the users current local time in the users current time zone. How would I go about doing this. Using a window operating system and visual studio 2008. Cheers Sean.

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[graph] Usage (and possible removal) of LEDA and Stanford GraphBase adaptors for Boost.Graph
by Jeremiah Willcock 06 Nov '09

06 Nov '09

Are there any users of the LEDA and Stanford GraphBase adaptors for Boost.Graph? They are no longer actively maintained and there have been bug reports that the LEDA adaptor does not work with current versions of LEDA. If they are no longer used, Andrew Sutton and I will consider deprecating and/or removing them. Please reply if you would like these components kept in Boost.Graph. -- Jeremiah Willcock

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RTTI disabled in boost.graph
by Koh Hwee Miin 06 Nov '09

06 Nov '09

I'm building boost library on windows xp (32-bit) using visual c++ 2005, with RTTI enabled. Then I received a warning D9025 stating that "overriding /GR with /GR-", and after checking the jamfile I find out that RTTI was disabled for boost.graph library. I'm assuming boost library will work correctly with RTTI enabled all the while, and all my other projects are built with RTTI enabled. Will there be any undefined behavior if I try to use boost.graph in other RTTI projects? _________________________________________________________________ Windows 7: Simplify what you do everyday. Find the right PC for you. http://windows.microsoft.com/shop

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[Serialization]
by Dylan Klomparens 05 Nov '09

05 Nov '09

Hello, I have 2 questions regarding the Serialization library: ========================= I have a function that I am using to load a serialized class, called "Configuration". A particular line in the function produces a warning message. Should I be worried about this warning? The function is below, with a comment denoting the warning-producing line. void Configuration::Save(const string& Name) { ofstream Out(Name.c_str()); if(Out.fail()) throw runtime_error("Error: unable to save configuration file."); boost::archive::text_oarchive Archiver(Out); Archiver << *this; // This line produces the warning. } The warning is: C4308: negative integral constant converted to unsigned type ... error is from file: \boost\mpl\print.hpp line: 51 ========================= In a separate question, I'm wondering why this code compiles: template<class Archive> void save(Archive& ar, const boost::asio::ip::udp::endpoint& endpoint, unsigned int version) { unsigned short Port = endpoint.port(); ar << endpoint.address().to_string(); ar << Port; } But this code does not compile: template<class Archive> void save(Archive& ar, const boost::asio::ip::udp::endpoint& endpoint, unsigned int version) { ar << endpoint.address().to_string(); ar << endpoint.port(); } The only difference is endpoint.port() is stored in a seperate unsigned short. ========================= Any help is much appreciated! -- Dylan

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