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

[inteprocess] Use of duration for the message_queue timed functions
by Achal Shah 10 Nov '09

10 Nov '09

A suggestion for the message_queue class is to overload timed_send and timed_receive so that they can accept a duration (say in milliseconds). I believe currently they work on an absolute time being reached. Thanks, - Achal.

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Two questions on boost::function
by CHRISTOPHE KOUDELLA, CITADEL INVESTMENT G 10 Nov '09

10 Nov '09

Hi, I am hopng to get some help from boost::function users on two questions I have. First, is it possible to extract the underlying functor out of a function? The reason for this is that it is useful to have the boost::function abstraction to move around functors in a generic fashion, but the interface is obviously limited to operator(), so being able to extract the underlying class out of a boost::function would be useful. I am thinking mostly about applied math applications in which functions are defined by more than an operator, whence the interface of boost::function is sometimes insufficient. Second, I was looking to implement a "function algebra" for boost::function (of a given arity, for a start). This algebra would implement sum, difference, product, composition, etc... operations on a pair of like boost::functions. In a template implementation in order to implement the operator() of the result boost::function, I need to access the result type and the argument types of the boost::functions being operated on. So, suppose I want to implement a product operation on a pair of template functors, then in order to define the operator() of the product of the functors, I need the result and argument types. Does boost::function make these types available as some typedefs? Does what I say make at all sense or would you proceed entirely differently in order to define such operations on boost::function? Thanks for any input, CK

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Boost.Asio: "The parameter is incorrect" when assigning native socket
by tiredashell 10 Nov '09

10 Nov '09

The error in the subject line occurs when attempting to assign a native socket to a Boost.Asio socket. I realize it's not very helpful since I'm not explaining where I am getting nativeSocket, but I was hoping someone let me know in general the cause of such an error, since there doesn't appear to be any documentation on it. I am almost positive that it is a valid socket, and its integer value is normally around 740. boost::asio::io_service ioserv; boost::asio::ip::tcp::socket s(ioserv); boost::system::error_code error; s.assign(boost::asio::ip::tcp::v4(), nativeSocket, error); if (error) cout << error.message() << endl;

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at_thread_exit() never getting called
by cowwoc 09 Nov '09

09 Nov '09

Hi, I am registering boost::this_thread::at_thread_exit() against one of my threads. When the main thread exits using "return 0" the at_thread_exit hook never gets invoked. Is this normal? Is there a way to hook the main thread shutting down? Thanks, Gili -- View this message in context: http://www.nabble.com/at_thread_exit%28%29-never-getting-called-tp26053513p… Sent from the Boost - Users mailing list archive at Nabble.com.

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getting shape of numpy array
by TheLonelyStar 09 Nov '09

09 Nov '09

Hi, I am trying to interaface a numpy array using boost::python::numeric::array. void function(numeric::array& a) { tuple shape=extract<tuple>(a.getshape()); double x; int i,j; for(i=0;i<shape[0];++i) for(j=0;j<shape[1];++j) x=extract<double>(a[make_tuple(i,j)]); } Now I had to add numeric::array::set_module_and_type("numpy", "ndarray"); to the module, hope that was correct. When I call this function in python, I get: AttributeError: 'numpy.ndarray' object has no attribute 'getshape' What is the correct way to do it? Thanks! Nathan -- View this message in context: http://old.nabble.com/getting-shape-of-numpy-array-tp26275771p26275771.html Sent from the Boost - Users mailing list archive at Nabble.com.

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[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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