December 2006 - Boost-users

Re: [Boost-users] Visual C++ 2005 help installing Boost
by Harry Georgakopoulos 17 Jan '07

17 Jan '07

I am having exactly the same problem as a previous user. Could you please show me how you fixed your boost build? I'm getting the following errors ...failed updating 120 targets ...skipped 80 targets... ...updated 847 targets... I don't know how to open the vsvars32.bat file in order to change the paths that Mr Kozicki suggested. Any help would be greatly appreciated. I have installed the latest SDK. Also, how do i get rid of the warnings? I know i need to define _SCL_SECURE_NO_DEPRECATE globally, but how do i do that exactly? Finally, how do i know i have a correct build install? How do i test it? Thank you Please send your response to hgeorgako(a)hotmail.com harry g.

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[regex] difficulties with the "Leftmost Longest" Rule
by Detlef Meyer-Eltz 11 Jan '07

11 Jan '07

I have a difficulty to predict, which part of a regular expression will match. Example: I have a regular expression for a general HTML tag: <[^>]*> combined with an expression for the body tag: <body([^>]*)> to: (<[^>]*>)|(<body([^>]*)>) This expression matches the text: <body bgcolor="white"> As both alternatives can match the input with the same length, I expected, that the repeated fouth part of the "Leftmost Longest" Rule would determine, which alternatve is chosen: 4. Find the match which has matched the first sub-expression in the leftmost position, along with any ties. If there is only on(e) such match possible then return it. // note the missing 'e' As the tag-expression has no sub-expression at all, the body-expression should win. Its sub-expression could match, but doesn't. It seems to me, that the sequence of the alternatives determines the match. Now I guess, that I misinterpreted 4.: its not a means to predict the matching alternative but only to find the one that matched accidentally? My software constructs lexers from elementary expressions automatically. So it's important for me to direct and predict the expected matching alternative. Are there any other rules? Does the sequence of the alternatives determine the match unmistakably? With Kind Regards, Detlef Meyer-Eltz

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[Boost.Array] gcc 4.1.2 vs. boost alignment
by Robert Mecklenburg 08 Jan '07

08 Jan '07

I've just upgraded my compiler to gcc 4.1.2 and tried the latest implementation of tr1 included with gcc. I've discovered the gcc array implementation is not what I expect: #include <boost/array.hpp> #include <tr1/array> #include <iostream> int main(int , char **) { boost::array<char, 6> barray; std::cout << sizeof(barray) << std::endl; std::tr1::array<char, 6> tr1array; std::cout << sizeof(tr1array) << std::endl; } When run this code produces: g++ foo.cpp && ./a.out 6 16 That is, the boost array is exactly the size I require 6 bytes, but the tr1 array is larger, 16 bytes. I believe this is due to the following declaration in 4.1.2/tr1/array: // Support for zero-sized arrays mandatory. value_type _M_instance[_Nm ? _Nm : 1] __attribute__((__aligned__)); The boost version is not aligned, but the gcc version is. Does the tr1 implementation require the alignment? If so, it appears that tr1::array is definitely not a suitable wrapper for C-style arrays since they aren't the same size! What's the scoop? Thanks, -- Robert

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portland group compilers (pg++, pgi, pgCC)
by Server Levent Yilmaz 05 Jan '07

05 Jan '07

Hi All, Please correct me if this is off topic here.. I sadly realized that there is no compiler toolset available for Portland Group Compilers (http://www.pgroup.com/) Before submitting an entry in the Support Request, and digging in (probably REALLY deep), I was wondering if there is anyone that has any experience with these compilers (failure or success, *nix or win), particularly for the following libraries: serialization multi_array bind lambda filesystem thank you, levent

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mpl::inherit_linearly question
by Ovanes Markarian 04 Jan '07

04 Jan '07

Hi! I am trying to create a static visitor using metapgramming. This approach worked fine in some test code, but now I face some problems. Let me first show some example: I've define an item_visitor template class: template <class Pair> //mpl::pair obtained from map sequence struct item_visitor { public: typedef typename Pair::second value_type; virtual void visit(value_type const& t) { assert(0 && "This function must be overriden in the concrete handler class!"); } }; template<class Seq> struct base_sequence_visitor : public boost::mpl::inherit_linearly < Seq , boost::mpl::inherit<boost::mpl::_1, item_visitor<boost::mpl::_2> > >::type {}; This example works fine and I can dispatch my type. Now I have some additional type, which provides a view to my structure. And I would like my visit to implemented as: virtual void visit(GenericView<Pair::second> const& t) { ... } In such a case I have to introduce a second parameter to the item_visitor template: template<class Pair, template<class> SomeView> struct item_visitor { ... }; Therefore the base_sequence_visitor must be updated as well to forward the View template: template<class Seq, template<class> SomeView> struct base_sequence_visitor : public boost::mpl::inherit_linearly < Seq , boost::mpl::inherit<boost::mpl::_1, item_visitor<boost::mpl::_2, SomeView> > >::type {}; Using this construct I get an error, that mpl::arg<2> does not have a type second. That means that the placeholder _2 does not get expanded. So I tried to "code around" and used the following trick: template<class> calss SomeView; template<class Pair> struct some_visitor : item_visitor<Pair, SomeView> {}; Then I added to the base_sequence_visitor template an additional argument, which specifies an item visitor class to be used: template<class Seq, template<class> ItemVisitor> struct base_sequence_visitor : public boost::mpl::inherit_linearly < Seq , boost::mpl::inherit<boost::mpl::_1, ItemVisitor<boost::mpl::_2> > >::type {}; And it compiles fine! But when I try to cast the base_sequence_visitor to some complete item_visitor type, which is really in the sequence I receive a compiler error, that cannot convert from 'base_sequence_visitor<Seq,ItemVisitor>' to 'ClassWhereSimpleVisitorIsDefined::simple_visitor<PairType> &' Do I miss something? With Kind Regards, Ovanes Markarian

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[Boost.Function] (too) loosly treated argument types
by Slawomir Lisznianski 02 Jan '07

02 Jan '07

Given example below, is there any way to enforce parameter type strictness? [-- Example begin: #include <boost/function.hpp> using namespace boost; // some kind of callback sig. // typedef function1<void, int &> signature; void fn1(int v) // notice arg by-value (say, user typo) { // here, assignments to `v' are lost after // return } void fn2(int & v) // OK { // here, assignments to `v' are // preserved after return } int main(int, char**) { // I want this to fail at compile-time... signature f1 = fn1; // ...and this to work signature f2 = fn2; return 0; } -- code end] On my compiler (g++ (GCC) 4.0.2 20051125) everything compiles fine but ideally, I'd like to fail the first case. Rationale: Users of my library register callbacks and occasionally mistype their function signature which causes them to modify temporaries rather than "out" variables. Thanks, -- Slawomir Lisznianski Paramay Group, LLC "Programs for Research Machinery"

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[Boost.Multi-Index] ICE w/ VC7.1
by Marc Viala 31 Dec '06

31 Dec '06

I'm just trying to use Boost.MultiIndex in a large project but I'm not being able to compile this library with VC 7.1.6030: I've got an ICE in file "apply_wrap.hpp" of Boost.MPL. I've tried to change the headers order but without success. My environment is: - Windows XP - Boost 1.33.1 - VC 7.1.6030 To demonstrate this ICE, you will find hereafter a code snippet. Thanks in advance. Marc Viala // MultiIndex Container #include <boost/config.hpp> #include <boost/multi_index_container.hpp> #include <boost/multi_index/composite_key.hpp> #include <boost/multi_index/ordered_index.hpp> #include <boost/multi_index/member.hpp> #include <boost/multi_index/key_extractors.hpp> // STL #include <string> using namespace boost::multi_index ; struct Item { const std::string& getCls() const { return _cls ; } const std::string& getId() const { return _id ; } std::string _cls ; std::string _id ; int _i ; int _j ; } ; void main() { typedef const_mem_fun< Item , const std::string& , &Item::getCls > key_cls ; typedef const_mem_fun< Item , const std::string& , &Item::getId > key_id ; typedef composite_key<Item,key_cls,key_id> ckey_clsid ; typedef composite_key< Item , ordered_non_unique<member<Item,int,&Item::_i> > , ordered_non_unique<member<Item,int,&Item::_j> > > ckey_ij ; typedef multi_index_container< Item, indexed_by< ordered_non_unique<key_id> , ordered_non_unique<key_cls> , ordered_unique<ckey_ij> > > ObjectContainer ; ObjectContainer c ; }

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[serialization and asio] Trying to serialize asio IPs
by Eoin O'Callaghan 30 Dec '06

30 Dec '06

Hello, my name is Eoin O'Callaghan. I wasn't sure if this email should have been sent to ASIOs own mailing list or this Boost one, hopefully this was an ok place. My bit of bother is in trying to use Boost.Serialization to save some IP addresses stored internally as Boost.ASIO asio::ip::address_v4 and address_v6 classes. I wonder has anyone any pointers as my attempts thus far are not getting me anywhere? The IP classes can be constructed from, and exported to, boost::array<unsigned char, ##> types so a solution for boost::arrays would probably be one road to a solution but unfortunately I can't successfully write a serialize function for boost::array. I've held back from posting my own attempts to save myself from embarrassment. But will do so if someone wants to see what I've tried. Kind regards, Eoin. -- Eoin O'Callaghan <eoin(a)zl.vc>

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[Thread] condition.cc test doesn't work..
by Giacomo Piccolo 29 Dec '06

29 Dec '06

Hello everybody, I've got a synchronization problem with two threads and I need a semaphore or a condition class in which a thread can wait on until that condition is verified. In other words i need to synchronize two or more threads and I need the wait() and notify() routines. I found some useful code in boost::thread libraries, but it seems I could not use it because it seems not completely built...or.. boh I don't really know. I tried also to build it lauching an executable builder I downloaded from the internet but I can't use it because don't have the root priviledges. I attach the source code and the errors I got. Is there anyone so kind to help me solving this little question? Thank you in advance! Giacomo

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Boost threads + MSVSC + /Za + client code
by Sohail Somani 29 Dec '06

29 Dec '06

Hi, With Visual C++, I can't seem to determine why if I simply include boost/threads/once.hpp, I need to enable language extensions for that translation unit. I'm going to dig into this further today but I would appreciate if someone has figured out a solution short of allowing language extensions. I can understand requiring it for building boost threads (as windows.h seems to have some extended syntax) but I'm not sure of the logic behind requiring client code to use it as well. Thanks for listening :) Sohail

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