April 2006 - Boost-users - lists.preview.boost.org

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>

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[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>

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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....

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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!

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[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)

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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

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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.

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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 >>>

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[Serialization] a newbie question about retrieving objects serialized through base class pointers
by t.sammoud 03 Apr '06

03 Apr '06

Hi all, I'm trying to reuse XML archives for some purpose. I'm serializing an array of pointers to a base class (let's call it A) containing pointers to derived classes (let's call them B and C). I'm wondering how does Boost distinguish between class types (A, B and C)when deserializing from the XML archive? (Is there any information in the XML archive or elsewhere giving the class name of the serialized object?) Regards Accédez au courrier électronique de La Poste : www.laposte.net ; 3615 LAPOSTENET (0,34 /mn) ; tél : 08 92 68 13 50 (0,34/mn)

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Serialization--a peculiar observation regarding operator<<
by Drumheller, Michael 03 Apr '06

03 Apr '06

The test program below (under boost 1_33, vc71) compiles fine, unless I change the "#if 1" to "#if 0", in which case it produces this: error C2679: binary '<<': no operator found which takes a right-hand operand of type 'double' (or there is no acceptable conversion) Can anyone explain why that should happen? A double is a double--why should '<<' care whether the rhs comes from funcall a variable? Note: The test program is clearly a nonsense program (in real life the role of foo() is played by some public (get-accessor) on klass--a very common pattern when doing a non-intrusive serialization). But I did not want to cloud the issue--I wanted to emphasize that the bug, if it is a bug, seems to have nothing to with klass. Thank you. Michael Drumheller -----------------------------------------------------------------begin-- ------------------------------------------------------------- #include <fstream> #include <boost/archive/text_oarchive.hpp> #include <boost/serialization/split_free.hpp> class klass {}; double foo() { return 3.1416; } namespace boost { namespace serialization { template<class Archive> void save(Archive &ar, const klass & b, const unsigned int ver) { #if 1 double x=foo(); ar << x; #else ar << foo(); #endif } template<class Archive> void load(Archive &ar, klass & b, const unsigned int ver){}//N/A for this demo }} BOOST_SERIALIZATION_SPLIT_FREE(klass); void out(const char *testfile, const klass & c) { std::ofstream ofs(testfile); boost::archive::text_oarchive oa(ofs); oa << c; } ----------------------------------------------------------------end----- ----------------------------------------------------------------- Michael Drumheller Boeing Phantom Works Mathematics and Engineering Analysis 425.865.3520 michael.drumheller(a)boeing.com

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