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

Re: [Boost-users] [multi_index] Serialization problemwithmulti_indexcontainer
by JOAQUIN LOPEZ MU?Z 04 Apr '06

04 Apr '06

----- Mensaje original ----- De: John Reid <john.reid(a)wibr.ucl.ac.uk> Fecha: Lunes, Abril 3, 2006 5:09 pm Asunto: Re: [Boost-users] [multi_index] Serialization problemwithmulti_indexcontainer > Joaquín Mª López Muñoz wrote: > > What this means is, if you've got elements a,b and its corresponding > > deserialized equivalents a',b', then a<b must yield the same value > > (true or false) as a'<b' --assuming it is operator< that is used > for sorting > > the index, which is the case if identity<element> is the key and > > the default sorting criterion is used. > > Ok thanks, that makes sense. I should have read that. > > My value_type has a data member that is a pointer to an object of > an > abstract class. I would like one index to be sorted by the > addresses of these objects. Yep, here's the problem, addresses' order is not preserved. > There seems no way to do this and have direct > serialisation of the multi_index container. Can you confirm? Yes, I'm afraid you can't directly serialize a multi-index container one of whose indices is of type ordered_non_unique and the key is the address of some mmember (or the whole element.) You'll have to stick to your current workaround --but you can improve it a bit: you don't really need to use an intermediate vector if you do the serialization process "by hand": save: save the number of elements. traverse the first index and save he visited elements. load: clear the container. load the number of elements N. repeat N times: load an element and insert it into the container. The overall effect is the same as with the intermediate vector, without any extra overhead. > Maybe I'm > missing something. Is there a reason why the serialisation > implementation does not recalculate the indices on the fly? Well, this is prewisely what's happening. Consider the following: struct element { element(int x,int y,int z):x(x),y(y),z(z){} int x,y,z; }; typedef multi_index_container< element, indexed_by< ordered_non_unique<member<element,int,&element::x> >, ordered_non_unique<member<element,int,&element::y> > > > multi_index_t; multi_index t m; element a(0,1,0); element b(1,1,1); element b(2,1,2); m.get<1>()insert(a); m.get<1>().insert(b,m.get<1>().begin()); m.get<1>().insert(c,m.get<1>().begin()); Now, if you traverse m by its index #0, the result is (0,1,0), (1,1,1), (2,1,2) whereas if you traverse it by index #1, the order is, because of our use of hinted insertion, the following: (0,1,0), (2,1,2), (1,1,1) So far so good. When saving and subsequently loading this container, Boost.MultiIndex guarantees that the traversal order of *every* index is preserved. Now, suppose serialization were implemented the naive way, that is, by just saving the elements as they are visited by the first index and loading through the first index again, just as you're doing in your workaround (no offense meant by the use of the word "naive", of course.) If you examine the process carefully, you can see that, when performed this way, index #0 is correctly replicated, but the resulting order of the loaded index #1 is (0,1,0), (1,1,1), (2,1,2) which does not match the original. This is why Boost.MultiIndex saves, additionally to the elements, enough extra information to restore index traversal orders in those cases where such order is not univocally determined (ordered non-unique, sequenced and random-access indices.) And when applying this extra information, the kind of sanity check you've been bitten by is routinely performed. I hope I've made myself clear, sorry for the long explanation. > Thanks for your response, > John. Thank you for using Boost.MultiIndex. I'm sorry out-of-the-shelf serialization capabilities can't serve your particular needs. Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

2 1

Linker errors with boost::regex with boost_1_33_1, STLport-4.6.2 and VS7.1
by Vijay Choudhary 04 Apr '06

04 Apr '06

Hi All, Is there a known issue of linker errors with using boost::regex library with STLport. If I don't install STLport I am able to build regex however I am getting linker error while trying to build after installing STLPort. Operating System:Win-XP IDE: Visual Studio .NET(version 7.1.3088) STLPort version: STLport-4.6.2 Boost versio:boost_1_33_1 The code which I have used in sample project: #include "stdafx.h" #include <boost/regex.hpp> #include <iostream> #include <string> int _tmain(int argc, _TCHAR* argv[]) { std::string line; boost::regex pat( "^Subject: (Re: |Aw: )*(.*)" ); while (std::cin) { std::getline(std::cin, line); boost::smatch matches; if (boost::regex_match(line, matches, pat)) std::cout << matches[2]; } return 0; } I got following linker errors: ConsoleApp1.obj : error LNK2019: unresolved external symbol "void __cdecl boost::re_detail::raise_runtime_error(class _STL::runtime_error const &)" (?raise_runtime_error@re_detail@boost@@YAXABVruntime_error@_STL@@@Z) referenced in function "void __cdecl boost::re_detail::raise_error<struct boost::regex_traits_wrapper<struct boost::regex_traits<char,class boost::w32_regex_traits<char> > > >(struct boost::regex_traits_wrapper<struct boost::regex_traits<char,class boost::w32_regex_traits<char> > > const &,enum boost::regex_constants::error_type)" (??$raise_error@U?$regex_traits_wrapper@U?$regex_traits@DV?$w32_regex_tr aits@D@boost@@@boost@@@boost@@@re_detail@boost@@YAXABU?$regex_traits_wra pper@U?$regex_traits@DV?$w32_regex_traits@D@boost@@@boost@@@1@W4error_ty pe@regex_constants@1@@Z) ConsoleApp1.obj : error LNK2019: unresolved external symbol "class _STL::basic_string<char,class _STL::char_traits<char>,class _STL::allocator<char> > __cdecl boost::re_detail::w32_transform(unsigned long,char const *,char const *)" (?w32_transform@re_detail@boost@@YA?AV?$basic_string@DV?$char_traits@D@_ STL@@V?$allocator@D@2@@_STL@@KPBD0@Z) referenced in function "public: class _STL::basic_string<char,class _STL::char_traits<char>,class _STL::allocator<char> > __thiscall boost::w32_regex_traits<char>::transform(char const *,char const *)const " (?transform@?$w32_regex_traits@D@boost@@QBE?AV?$basic_string@DV?$char_tr aits@D@_STL@@V?$allocator@D@2@@_STL@@PBD0@Z) Debug/ConsoleApp1.exe : fatal error LNK1120: 2 unresolved externals However if I comment call to function boost::regex_match() in sample code , then I am able to build it. Regards: Vijay Kumar

2 1

does ptr_* solves this?
by Marco Correia 04 Apr '06

04 Apr '06

Hi, I have an heterogeneous container holding pointers to objects of type B. I want to insert objects of type D1,D2,... that derive from B, and I want to do that using a custom stl like allocator, for example: B* obj = my_alloc<D>::allocate(1); obj = new (obj) B(); container.insert(obj); My problem is that when an object is removed from the container, I have to explicitely deallocate it from my allocator, but the static info was lost, so I cannot do my_alloc<?>::deallocate(1,oj); I've asked in boost irc channel, and someone told me ptr_* boost libraries solve this problem, is this correct? thanks -- Marco Correia <mvc(a)netcabo.pt>

3 4

[BGL] GraphML ?
by Tiago de Paula Peixoto 04 Apr '06

04 Apr '06

Hi. Is there any planned support for GraphML i/o (http://graphml.graphdrawing.org/) in BGL? Has anyone played with this, and has experimental code? I think I saw it mentioned in the BGL documentation somewhere, but I can't find it. Thanks a lot. -- Tiago de Paula Peixoto <tiago(a)forked.de>

3 4

bind on a iterator zip.
by chun ping wang 04 Apr '06

04 Apr '06

std::for_each(boost::make_zip_iterator(boost::make_tuple(beg1, beg2, beg3)), boost::make_zip_iterator(boost::make_tuple(end1, end2, end3)), ); now i want acess each indivdual tuple values using lambda and bind. How would i do that? My basic question is how would I use lambda to access the tuples value or each iteration value....

1 0

Perl Regex Question
by admin＠geocodenet.com 03 Apr '06

03 Apr '06

Hi all, I'm sure this is just a configuration issue, but I'm not sure where my config is wrong. I'm using boost_regex_search, and capturing subgroups. When I use this regular expression: ^(*.)a(*.) On this string: "Management" I end up with the following matches: 0==> Management 1==> Man 2==> gement Should this be returning the following matches? 0==>Management 1==>M 2==>nagement 3==>Management 4==>Man 5==>gement Or am I getting exactly what I'm supposed to be getting here? Also, the default syntax is Perl syntax, correct? Thanks!

4 3

[review] promotion traits - reminder
by Tobias Schwinger 03 Apr '06

03 Apr '06

Dear users & members of Boost, half of the scheduled review period is over and there were no reviews, so far. Therefore I want to welcome you, once again, to evaluate the proposed Boost software. The end of the review period is scheduled for April 6, so please try to post your review before then. Download URL ============ http://cpp-experiment.sourceforge.net/promote-20050917.tar.gz About the submission ==================== The Promotion Traits extend Boost.TypeTraits with templates that compute the type after promotion has been applied. Example: // given template<typename T> struct some_algorithm; template<> struct some_algorithm<int> { [...] }; // [...] more specializations // , [...] some_algorithm< typename integral_promotion<T>::type > [...] // makes some_algorithm work for any type T that promotes to an integer // (that is enums and smaller integral types) without the need for // additional specialization It's a small submission so you probably won't notice that you're working before you're done... Review questions ================ Please always explicitly state in your review, whether you think the library should be accepted into Boost. You might want to comment on the following questions: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? - Are you knowledgeable about the problem domain? Regards, Tobias (Review Manager)

1 0

Use count callback
by Dave 03 Apr '06

03 Apr '06

Hello all, I'm using shared_ptr<foo> and would like to be notified, via a callback, when the use count for a foo object becomes > N. I wish to receive notification for no shared_ptr types other than those instantiated with foo. Is this possible? Thanks, Dave

2 1

Re: [Boost-users] [BULK] Use count callback
by Sohail Somani 03 Apr '06

03 Apr '06

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org > [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Dave > Sent: Monday, April 03, 2006 12:47 PM > To: boost-users(a)lists.boost.org > Subject: [BULK] [Boost-users] Use count callback > Importance: Low > > Hello all, > > I'm using shared_ptr<foo> and would like to be notified, via > a callback, > when the use count for a foo object becomes > N. I wish to receive > notification for no shared_ptr types other than those > instantiated with foo. > Is this possible? Specialize for foo? Might be kind of tedious though.

1 0

Re: [Boost-users] Serialization--a peculiar observation regarding operator<<
by Drumheller, Michael 03 Apr '06

03 Apr '06

Robert, Oliver, and Dave: That seems to have fixed it. I'm embarrassed for not having figured it out. Thank you very much. Michael P.S. This is totally off-topic, but I'd be a lot *less* embarrassed if the VC compiler error messages were not so lame. This compiler has managed to annihilate huge segments of my life with messages of the form "Could not do the right thing with an X" instead of "Could not do the right thing with an X; a Y was expected." In this case it should have said "binary '<<': no operator found which takes a right-hand operand of type 'double' (or there is no acceptable conversion to 'const double')" Just that tiny rephrasing words would have saved a lot of pain. Alas. Anyway: Thanks again you guys. --MD >>> ------------------------------ >>> >>> Message: 5 >>> Date: Mon, 3 Apr 2006 08:55:30 -0700 >>> From: "Robert Ramey" <ramey(a)rrsd.com> >>> Subject: Re: [Boost-users] Serialization--a peculiar observation >>> regardingoperator<< >>> To: boost-users(a)lists.boost.org >>> Message-ID: <e0rghh$dua$1(a)sea.gmane.org> >>> >>> hmm >>> >>> The operator ar << takes a reference to a const argument. >>> >>> It looks like the compiler is objecting to taking the >>> reference to an argument on the stack >>> >>> ar << foo(); >>> >>> which seems like a good idea to me. In this case there >>> would be no problem, but in the case where the return of >>> foo() would be a "tracked" type, this would break the >>> serialization system. >>> >>> Robert Ramey >>> Message: 1 >>> Date: Mon, 3 Apr 2006 10:33:55 +0200 >>> From: "David Klein" <d.klein(a)ascaron.com> >>> Subject: Re: [Boost-users] Serialization--a peculiar observation >>> regardingoperator<< >>> To: <boost-users(a)lists.boost.org> >>> Message-ID: >>> <D3A9DB446C206D4EA2C2CCFD637362490173A0C8(a)exchsrv.ascaron.lan> >>> Content-Type: text/plain; charset="us-ascii" >>> >>> hi michael, >>> >>> try changing: >>> >>> double foo() { return 3.1416; } >>> >>> to >>> >>> const double foo() { return 3.1416; } >>> >>> HTH dave >>> >>> Message: 2 >>> Date: Mon, 3 Apr 2006 10:39:28 +0200 >>> From: "Oliver Mutz" <mutz(a)isdcad.de> >>> Subject: Re: [Boost-users] Serialization--a peculiar observation >>> regardingoperator<< >>> To: <boost-users(a)lists.boost.org> >>> Message-ID: <001501c656fa$21bb3ed0$050aa8c0(a)int.isdcad.de> >>> Content-Type: text/plain; charset="us-ascii" >>> >>> >>> Try changing the return type of foo() to const double. >>> For the reason see the ratinale page in the serialization >>> documentation. >>> >>> Oliver >>>

1 0