- Boost-users - lists.boost.org

Re: [Boost-users] [multi_index] passing 'const TYPE' as 'this' argument discards qualifiers
by damny＠web.de 27 Dec '07

27 Dec '07

ahh, very nice. please excuse my thick-wittedness. but ... what if, if i would like to add an additional, unique key to my structure; a last update time, maybe. name-identifer-time >> value; valu1:=map[nme1], valu1:=map[idf1], valu1:=map[time1] in this case bimap will not solve my problem and multiindex will be the best solution. is that right? and for interest, how to solve the original problem in this case? thnx daniel _____________________________________________________________________ Der WEB.DE SmartSurfer hilft bis zu 70% Ihrer Onlinekosten zu sparen! http://smartsurfer.web.de/?mc=100071&distributionid=000000000066

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Re: [Boost-users] [review] Fast track formal review of Forward library begins today
by Tobias Schwinger 27 Dec '07

27 Dec '07

shunsuke wrote: > "A FunctionObject that can be used with boost::bind" is not good. :-) It's much better than using cryptic Concept names in tutorial-style documentation, IMO. We have a bunch of Function object Concepts defined in Fusion - and I have to say I'm waiting for the day I can remove them IOW result type computation crutches are not needed anymore... Regards, Tobias

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time date newbie problem
by Michał Nowotka 27 Dec '07

27 Dec '07

Hi, I'm a date time library newbie and currenty working on simple web server implementation in C++. I want to generate string containing actual date in following format: Wed, 26 Dec 2007 17:33:47 GMT Date time documentation is so complicated and I can't find clear answer how to do that. Can you help me? -- Cheers, Michał Nowotka

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Re: [Boost-users] [multi_index] passing 'cons t TYPE' as 'this' argument discards qualifiers
by "JOAQUIN LOPEZ MU?Z" 27 Dec '07

27 Dec '07

----- Mensaje original ----- De: damny(a)web.de Fecha: Martes, Diciembre 25, 2007 5:17 pm Asunto: [Boost-users] [multi_index] passing 'cons t TYPE' as 'this' argument discards qualifiers Para: boost-users(a)lists.boost.org > merry xmas everyone, Merry Xmas :) [...] > class cClass { > private: > int att1; > public: > std::string nme; // name > int idf; // identifier > cClass(); > cClass(std::string nme, int idf); > int get_attribute(); > }; > [...] > mMapByNme::iterator itrNme = locMsg.get<0>().find("name1"); > mMapByIdf::iterator itrIdf = locMsg.get<1>().find(456); > printf( "att1 = %d\n", itrNme->get_attribute() ); [...] > main.cpp: In function `int main()': > main.cpp:33: error: passing 'const cClass' as 'this' argument of > 'int cClass::get_attribute()' discards qualifiers > Process terminated with status 1 (0 minutes, 20 seconds) > > any hints how to solve the problem? The problem here is that elements of a multi_index_container are immutable, and the iterators ony grant const access to them. In this regard, the behavior is the same as that of a regular std::set. To solve your particular problem you can const-qualify the offending member function: int get_attribute() const; > how to encapsulate this special multi_index into a class, that > fits the above description of the needed 'map'. You should probably consider whether Boost.Bimap could be a better approach, but I see you're already discussing this issue with Matías. > are there possibilities to avoid the 'std::string' for the 'name' > key? I'm not getting this question. Could you please elaborate? > where are the more easier examples for C++-templates/boost > newbies like me :o) ? HTH, Joaquín M López Muñoz Telefónica, Investiación y Desarrollo

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[lambda] problem with if_then_else_return
by Zeljko Vrba 27 Dec '07

27 Dec '07

I have a problem with the following statement: return std::accumulate( qrun_.begin(), qrun_.end(), svt, _1 < if_then_else_return( _2 != (acct*)0, bind(&acct::get_avt, _2), (unsigned)-1)); Basically, I want to find the minimal value of get_avt() over all non-null members of qrun_ which is declared as std::vector<acct*>. I get the following compiler error with SunCC 5.9: Error, badbinaryop: The operation "unsigned<const boost::lambda::detail::return_type_deduction_failure< boost::lambda::detail::return_type_2_ifthenelsereturn<1, 1, 1, 0, unsigned, const unsigned>>" is illegal. The get_avt method is declared as: unsigned get_avt() const Removing the const qualifier doesn't help. Replacing (unsigned)-1 with _1 generates the same error, but with "const unsigned" replaced by "unsigned&". Replacing (unsigned)-1 with bare 0 compiles without any error, but does not compute what I want. Any suggestions about what am I doing wrong?

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Re: [Boost-users] [multi_index] passing 'const TYPE' as 'this' argument discards qualifiers
by damny＠web.de 26 Dec '07

26 Dec '07

hi mathias, thanks for your response. but i think there is a misapprehension. i want something like <http://www.boost.org/libs/multi_index/doc/tutorial/index.html>. "indexed by shape" should meet my "index by name" and "indexed by number" should meet my "index by identifier", so i can get the associated element value either by locMap[nme] or by locMap[idf], or something like that :o) there are 3 sets, a name key set, a identifier key set and an element value set; and there mapping. in a bimap are only 2 sets, a key set and an element set, which can swapped. thats not what i want. best regards, daniel _____________________________________________________________________ Der WEB.DE SmartSurfer hilft bis zu 70% Ihrer Onlinekosten zu sparen! http://smartsurfer.web.de/?mc=100071&distributionid=000000000066

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[Serialization] BOOST_CLASS_EXPORT_GUID_1 macro issue (SVN Trunk)
by Richard Turrin 26 Dec '07

26 Dec '07

Hi, I am in the midst of migrating some projects into VS 2008, and have downloaded and built the boost library from the SVN Trunk (retrieved on 18 December, 2007 @ 4:09 pm) which seems to satisfy support for VS 2008. However, I was having a problem compiling some code that calls the macro BOOST_SHARED_POINTER_EXPORT (the code uses Boost serialization on some shared_ptr objects). I was running into the following error: MyOuterClass.h(11) : error C2371: '`anonymous-namespace'::boost_serialization_guid_initializer___LINE___1' : redefinition; different basic types MyOuterClass.h(10) : see declaration of '`anonymous-namespace'::boost_serialization_guid_initializer___LINE___1' The issue seems to be located in the BOOST_CLASS_EXPORT_GUID_1 macro, line 160 in serialization/export.hpp. The following macro is not expanding as desired: #define BOOST_CLASS_EXPORT_GUID_1(T, K) \ ... BOOST_PP_CAT(boost_serialization_guid_initializer_, __LINE__ ## _1) \ I believe the author of this line intended that __LINE__ would be replaced with a line number where the macro is implicitly called from, and THEN concatenated with the _1 token. Unfortunately, it seems that the two tokens are concatenated first creating __LINE___1 in the process. I have a trivial workaround: #define EXPAND(x) x #define BOOST_CLASS_EXPORT_GUID_1(T, K) \ ... BOOST_PP_CAT(boost_serialization_guid_initializer_, EXPAND(__LINE__) ## _1) \ This allows me to compile without the error (under VS 2008). Please advise if there is a better or more appropriate solution. Also, I wasn't sure whether _1 was a token literal or an mpl (Boost Metaprogramming library) placeholder. I realize that 1.35 is not yet ready for release. So, I'm not expecting everything to work correctly. So far, this is the only issue I've run into. Let me know if you need more information. Thank you for your time! Best Regards, Rich Turrin

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problem with boost/ublas/storage
by nksallem＠laas.fr 26 Dec '07

26 Dec '07

Hi, First Merry Christmas Second, I'm facing the same issue that the one described here : http://lists.boost.org/MailArchives/ublas/2007/08/2247.php As I didn't found a reply, I'm posting new one. I'm runnig version 10.34.01 and using ublas for a linear least square resolution problem. the error was : -------------------------------------------------------------------- ...ublas/storage.hpp at line 196: i < size ** std:exception ** bad index ------------------------------------------------------------ It seems to be a resize() problem on matrixes, any suggestions? Thanks

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Re: [Boost-users] [review] Fast track formal review of Forward library begins today
by Kirit Sælensminde 26 Dec '07

26 Dec '07

Joel de Guzman wrote: > David Abrahams wrote: >> on Fri Dec 07 2007, shunsuke <pstade.mb-AT-gmail.com> wrote: >>> FWIW, starting from Abrahams' callable and functionN, I've been implementing a similar library: >>> http://tinyurl.com/vd4r5 , which regards Boost.Functional/Forward facility >>> as one of higher-order functions, `perfect`. >> Hmm. Did anyone reply to this? I think if someone points to an >> alternative library with that level of maturity during a review, it >> shouldn't be ignored. We should at least have a discussion of the >> relative merits of the two approaches before taking a vote. > > I think the Egg library is awesome. Is it in the review queue yet? > If not, it should be. My opinion here is that it can co-exist with > the Forward library just as boost.bind can coexist with boost.lambda. > It's not always a matter of which is more sophisticated. Certainly, > bind is a subset of lambda. Yet, even with the simplicity of bind, > it is sufficiently useful in many applications. I'd say the same for > Egg and Boost.Functional. > > Let's have more FP in C++! :-) I've got to agree. The egg library looks like an incredible bit of work. I'd love to see this in Boost too. I for one though do find it confusing when there is overlap between libraries because normally the documentation of the libraries don't discus each other's strengths and weaknesses and why you might want to choose one over the other. That isn't to say that there shouldn't be overlap between libraries, but it would be nice if the documentation of the libraries cross tied a bit more. K -- http://www.kirit.com/

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Re: [Boost-users] [review] Fast track formal review of Forward library begins today
by David Abrahams 26 Dec '07

26 Dec '07

on Fri Dec 07 2007, shunsuke <pstade.mb-AT-gmail.com> wrote: > John Torjo wrote: >> Hi all, >> >> The formal review of the Boost.Functional/Forward library, proposed by >> Tobias Schwinger, begins today : >> >> Boost.Functional/Forward provides decorator function objects to have an >> n-ary, >> generic function object accept both RValues and mutable LValues. > > Sorry, this is not a review. Ignore this if irrelevant. > > Was boost::detail::functionN family in Boost.Accumulators considered? > That seems more advanced than Boost.Functional/Forward. > > FWIW, starting from Abrahams' callable and functionN, I've been implementing a similar library: > http://tinyurl.com/vd4r5 , which regards Boost.Functional/Forward facility > as one of higher-order functions, `perfect`. Hmm. Did anyone reply to this? I think if someone points to an alternative library with that level of maturity during a review, it shouldn't be ignored. We should at least have a discussion of the relative merits of the two approaches before taking a vote. -- Dave Abrahams Boost Consulting http://www.boost-consulting.com

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