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boost::sub_range vs boost::iterator_range
by Victor A. Wagner Jr. 11 Dec '05

11 Dec '05

After reading (and re-reading a few times) the documentation on range, it appears to me that there is little (if any) difference between: boost::sub_range<T> and boost::iterator_range<T::iterator> I've been working on a N way merge algorithm for work, and thought it might be a nice chance to learn bost::range and maybe even get it general enough to submit for boost utility some day. At any rate. Here's the problem: I've written a test case and two implementations (work still in progress) but I get compile errors when I try to use sub_range. the code can be found at http://www.noidea128.org/sourcefiles/15646~ to change the program from compiling/running the iterator_range to sub_range simply change the lne from: Nway_merge(contain, ourmerged); -to- SNway_merge(contain, ourmerged); my compiler (VC-8_0) gives two errors which I cannot decipher. Any assistance would be appreciated.... especially if I've misunderstood why sub_range instead of iterator_range. Victor A. Wagner Jr. http://rudbek.com The five most dangerous words in the English language: "There oughta be a law"

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mapping strings to indexes at compile time - MPL map?
by Paul Baxter 10 Dec '05

10 Dec '05

I have a fixed list of parameter names and with each an associated set of attributes. I wish to access the attributes via the parameter name rather than the equivalent list entry index. In the past, we've created ENUMs with meaningful names to represent the parameter name->index mapping but I can't help feeling there must be a better way usng the name directly without this extra artificial mapping type. Rather than access an attribute of a given parameter via a numerical index into an array of attribute structures or similar, I'd like to be able to use the name field directly. I would like the name->index mapping to happen at compile time so as not to include some run-time overhead. // Define a list of all allowable parameter names along with associated attributes .. // Not necessarily the required syntax unsigned config_offset = parameter["third parameter"].get_byte_offset(); I want a compile time error if "third parameter" isn't a valid name, and if it is valid, I want the code to reduce to parameter[3].get_byte_offset() which the compiler would further reduce to an inlined access to the right attribute. I've tried looking at the MPL map, but am having difficulty with the documentation though I confess part of this may be a lack of familiarity with meta template programming. Can anyone point me to the right area of Boost for doing this name->index mapping at compile time.

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ANN: asio formal review begins
by Jeff Garland 10 Dec '05

10 Dec '05

I'm cross-posting this announcement to the user list as I expect that there will be high interest in this review. Please post reviews on the developer list. ------------- All - Today (Dec 10th) is the start of the format review of the Asynchronous I/O library (asio) library by Christopher Kohlhoff. The review will run until Friday December 23rd. I will be serving as review manager. From the library synopsis: Boost.Asio is a cross-platform C++ library for network programming that provides developers with a consistent asynchronous I/O model using a modern C++ approach. Downloads of the library as well as online documentation can be found at: http://asio.sourceforge.net/ (please refresh the page if you don't see "Boost Review Material" at the top) http://asio.sourceforge.net/boost-asio-proposal-0.3.6/libs/asio/doc/ As usual, please state in review comments how you reviewed the library and whether the you think the library should be accepted into Boost. Further guidelines for writing reviews can be found on the website at: http://www.boost.org/more/formal_review_process.htm#Comments Please review early and often! Thanks, Jeff ******************************************************* A Few Library Details: ******************************************************* Supported Platforms The following platforms and compilers have been tested: * Win32 using Visual C++ 7.1 and Visual C++ 8.0. * Win32 using Borland C++Builder 6 patch 4. * Win32 using MinGW. * Linux (2.4 or 2.6 kernels) using g++ 3.3 or later. * Solaris using g++ 3.3 or later. * Mac OS X 10.4 using g++ 3.3 or later. Rationale The Boost.Asio library is intended for programmers using C++ for systems programming, where access to operating system functionality such as networking is often required. In particular, Boost.Asio attempts to address the following goals: * Portability. The library should support, and provide consistent behaviour across, a range of commonly used operating systems. * Scalability. The library should allow, and indeed encourage, the development of network applications that scale to hundreds or thousands of concurrent connections. The library implementation for each operating system should use the mechanism that best enables this scalability. * Efficiency. The library should support techniques such as scatter-gather I/O, and allow protocol implementations that minimise data copying. * Model Berkeley sockets. The Berkeley sockets API is widely implemented and understood, as well as being covered in much literature. Other programming languages often use a similar interface for networking APIs. * Ease of use. Lower the entry barrier for new users by taking a toolkit, rather than framework, approach. That is, try to minimise the up-front investment in time to just learning a few basic rules and guidelines. After that, a library user should only need to understand the specific functions that are being used. * Basis for further abstraction. The library should permit the development of other libraries that provide higher levels of abstraction. For example, implementations of commonly used protocols such as HTTP. Although the current incarnation of Boost.Asio focuses primarily on networking, its concepts of asynchronous I/O can be extended to include other operating system resources such as files.

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Documentation Typo
by Merrill Cornish 09 Dec '05

09 Dec '05

In the documentation for BOOST_WARN_NO_THROW() and friends, http://www.boost.org/libs/test/doc/components/test_tools/reference/index.ht…, the second sentence starts, "Ttool execute the supplied statement...". Notice the Ffirst word. Merrill

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[Boost-users ] [program options: Is there a way to remove some options from the variables_map?]
by Suresh T 09 Dec '05

09 Dec '05

hi, I would like to know if there is any method provided to remove selected options from variables map. I am using program options to parse and assign initial values to all parameters in an application. I have a situtation where i would like to remove some of the parameters from the store ( variables_map) before i call notify. ( before the program options part is called i get a list of options that are already initialized. These options should not be parsed again) Currently i am using a dirty approach of removing the options from the command line/ini file. If i can directly remvoe the options from the store it will be much easier ( and safer). As allow_unregistered is supported now, i would not have to bother about unknown options in the command line. Thanks & --------------------------------------------------------------------------------------------------------- Regards, Suresh.T

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serialization: loading std::map replaces existing map data objects
by Peter Whaite 09 Dec '05

09 Dec '05

I was kinda hoping I could construct a std::map with default data objects, then use serialization to overwrite some of the their member variables. Unfortunately serialization completely replaces the map's data objects. I see in 'collections_load_imp.hpp' what I presume is code to do what I want but it is commented out: template<class Archive, class Container, class InputFunction, class R> inline void load_collection(Archive & ar, Container &s){ // if(0 != (ar.get_flags() & boost::archive::no_object_creation)) // copy_collection<Archive, Container>(ar, s); // else rebuild_collection<Archive, Container, InputFunction, R>(ar, s); Is there any chance that copy_collection will work one day, or has it been abandoned? --- Peter Whaite.

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[date_time] time_from_string() bug?
by Michael Lin 09 Dec '05

09 Dec '05

Hi all, I come across a bug in boost::posix_time::time_from_string(); try { ptime t1(time_from_string("2005-01-01")); cout << to_simple_string(t1) << endl; } catch (...) { cout << "exception thrown" << endl; } The above code will strangely output: "2005-Mar-25 13:01:01" time_from_string() will parse "2005-01-01 12", "2005-01-01 12:23" and "2005-01-01 12:23:33" correctly. It will even parse "2005-01-01 34" to the next day and output "2005-Jan-02 10:00:00" Does anyone have a fix for this bug? It should either parse correctly or it should throw an exception. Thanks Michael

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implicit() in program_options::value_semantic
by Alterman, Eugene 09 Dec '05

09 Dec '05

Program options library overview doc illustrates using implicit() for specifying 0 or 1 token value, but this function does not seem to be present in reference doc or source files (as of 1.33.1).

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[numeric/conversion] Possible bug in converter.hpp ?
by Eric Belanger 08 Dec '05

08 Dec '05

Hello, I'm trying to build openvrml 0.15.10 which uses the Boost library. However, I get the following error message: /usr/include/boost/numeric/conversion/detail/converter.hpp:233: error: expected unqualified-id before numeric constant /usr/include/boost/numeric/conversion/detail/converter.hpp:238: error: type/value mismatch at argument 6 in template parameter list for 'template<class expr0, class expr1, class TT, class TF, class FT, class FF> struct boost::numeric::convdetail::for_both' /usr/include/boost/numeric/conversion/detail/converter.hpp:238: error: expected a type, got '0l' /usr/include/boost/numeric/conversion/detail/converter.hpp:238: error: 'type' does not name a type which appears to be a problem with the header file. I'm using Linux with gcc 4.0.2. The problematic code from converter.hpp is : template<class PredA, class PredB> struct combine { typedef applyBoth<PredA,PredB> Both ; typedef void None ; //LINE 233 typedef typename PredA::do_apply do_applyA ; typedef typename PredB::do_apply do_applyB ; typedef typename for_both<do_applyA, do_applyB, Both, PredA, PredB, None>::type type ; //LINE 238 } ; Can anyone confirm that there is indeed a problem with the converter.hpp header file? If so, how could it be fixed? Thanks. Regard, Eric Belanger -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.

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interval library: simple rounding control?
by Reinder Verlinde 08 Dec '05

08 Dec '05

I am trying to use the boost interval library. It works fine, until I try to use exp, log, or one of the goniometric functions: error: 'struct boost ::numeric::interval_lib::detail::save_state_unprotected< boost::numeric::interval_lib::rounded_arith_opp< double, boost::numeric::interval_lib::rounding_control<double> > >' has no member named 'cos_up' and similar errors for cos_down, sin_up, etc. I read the documentation, but could not find what to do about this. From <http://www.boost.org/libs/numeric/interval/doc/rounding.htm>, I get the impression that I need to write a rounding policy, but am at a loss about how to do this. My problem is twofold: - getting this to be compiled using erroneous versions of this where cos_up and cos_down simply call 'cos' - getting correct versions of cos_up, etc. Any help is appreciated. Reinder

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