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

[review] promotion traits - review period extended until April 9.
by Tobias Schwinger 06 Apr '06

06 Apr '06

Dear users & members of Boost, I decided to extend the review period of the fast-track review for Promotion Traits until April 9 because there were only three reviews until now. That is, you have another three days to submit your evaluation of the proposed Boost software. Cheer up, it's a small & fast-to-track submission! We're very much looking forward to your reviews. 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 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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(no subject)
by Karim Bakir 06 Apr '06

06 Apr '06

Hi I want to know if it exists in boost multi array a method to empty it. thanks. --------------------------------- Nouveau : téléphonez moins cher avec Yahoo! Messenger ! Découvez les tarifs exceptionnels pour appeler la France et l'international.Téléchargez la version beta.

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sregex_token_iterator
by Jean-Sebastien Vachon 06 Apr '06

06 Apr '06

Hi All, I have a string in the following form: w="id = 10" C=field1 G=GeoRaster X=leMHG08wViX2quWNB All I want is to iterator onto the key/values pairs. w "id = 10" C field1 G GeoRaster X leMHG08wViX2quWNB The key/value pairs are separated by spaces. However, I can not simply use a space pattern to iterate over my input string since the W option allows the user to use "" to include spaces. Can someone tell me what is wrong in the following code? oParametersValue represents my input string. regex eParam("(.)=(\"?.*\"?)", regex::normal | regbase::icase); int const sub_matches[] = { 1, 2 }; // key, value sregex_token_iterator oIter(oParametersValue.begin(), oParametersValue.end(), eParam, sub_matches); sregex_token_iterator j; while (oIter != j) { std::cout << *oIter++ << std::endl; } Thanks

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Regex question
by Peter Sliepenbeek 06 Apr '06

06 Apr '06

First some examples: -- std::string input = "u"; std::string expression = "[^UuMmFf]*"; std::string replacement = "Unknown"; boost::regex regular_expression(expression); std::string output = boost::regex_replace(input, regular_expression, replacement, boost::match_default); Boost: output = "UnknownuUnknown" $ echo 'u' | sed 's/[^UuMmFf]*/Unknown/g' UnknownuUnknown Expected. -- std::string input = "x"; std::string expression = "[^UuMmFf]*"; std::string replacement = "Unknown"; boost::regex regular_expression(expression); std::string output = boost::regex_replace(input, regular_expression, replacement, boost::match_default); Boost 1.33.1: output = "UnknownUnknown" Prior: "Unknown" $ echo 'x' | sed 's/[^UuMmFf]*/Unknown/g' Unknown The result generated by Boost 1.33.1 is not expected! -- std::string input = " "; std::string expression = "[^UuMmFf]*"; std::string replacement = "Unknown"; boost::regex regular_expression(expression); std::string output = boost::regex_replace(input, regular_expression, replacement, boost::match_default); Boost 1.33.1: output = "UnknownUnknown" Prior: "Unknown" $ echo ' ' | sed 's/[^UuMmFf]*/Unknown/g' Unknown The result generated by Boost 1.33.1 is not expected! -- The expression "[^UuMmFf]*" will greedily match the input string. In the case of "x" or " " (space) the expression will match the whole string! There should not be a match on an empty string! Considering these examples I would mark this as a bug! Thanks, P. Sliepenbeek __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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Re: [Boost-users] Serialization: crash at launch of program (duetoboost::serialization::base_object)
by RIVASSEAU Jean Noel 06 Apr '06

06 Apr '06

I have tried to use versioning. Exact same problem. More explanations: if I use the version facility, and at load I switch the boost::serialization::base_object<MyBaseClass> depending on the version, the same crash will happen. Eg: this code: if (version == 0) { boost::serialization::base_object<MyBaseClass_1> } Else { boost::serialization::base_object<MyBaseClass_2> } Will cause the same crash. So, could you look at the code, because currently there is no way to change the base class of an object appearing in serialized archives, if you want to be able to read old archives. It seems like there is a bug, if the base_object is used several times with different classes, the crash will appear. Thanks Jean-Noël -----Message d'origine----- De : boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] De la part de Robert Ramey Envoyé : mercredi 5 avril 2006 17:15 À : boost-users(a)lists.boost.org Objet : Re: [Boost-users] Serialization: crash at launch of program (duetoboost::serialization::base_object) The "version" facility is provided for maintaining the ability to read old archives. It doesn't sound like you're using this and its sounds like you should be. Robert Ramey "RIVASSEAU Jean Noel" <JN.RIVASSEAU(a)oberthurcs.com> wrote in message news:87F60F7FA02FF749AFB02BD9FCAA6B0401074928@naserv31.nanterre.oberthurcs.com... Hello, My program crashes at launch (not even a exit(0) as the first line of main(int argc, char *argv[]) will stop it from crashing), due to the BSL. What I am trying to do is: I have a class, whose serialization is split (eg, save and load functions are provided, and they are different). Now this class had a parent class, so I used to call boost::serialization::base_object<MObject>() on the base class MObject. However I want to change the parent of my class to a different class. I also want to update my old archives, so I decided to leave the load function of my class untouched, while I would change the save function, to update the call to base_object to the new parent class (not MObject anymore). I thought it would work, since it would load the old archive using the same method, but save it using the new, so I would have ran only one time the program and the archive would be updated (then, of course, before running it again I would have to recompile it one more time with the correct changes to the load function). But it does not work as expected, since it seems the BSL does not like the fact that save and load functions calls to boost::serialization::base_object do not specify the same base class. It does not complain at compile time but crashes at run time before even entering main and certainly before loading any archive. The crash is due to a NULL pointer, I have tried to debug with gdb but the crash apparently occurs on the _libkernel32_a_iname () so I do not not know where it is (too low level for me). Robert, do you have an idea what is going on? I suspect a bug - however if it is "normal" behaviour (I think it should then throw an exception rather than crash), *** Tell that to the author of _libkernel32_a_iname () do you have an idea how could I update my archives? I need to change the parent of this class, but need to be able to read my old archives - and changing them "by hand" by looking into the XML archive code is tool hard. Thank you, regards Jean-Noël Rivasseau _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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[Multi_Array] distiontion be tween views, array_view, sub_array_view etc.
by Robert Ramey 06 Apr '06

06 Apr '06

The multi_array library seems to a good fit for a situation which I'm currently dealing with. I'm having a lot of problems understanding how to use it though. I can't really understand the distinction between the differing types of views, subviews etc. I would sort of expect that a new instance of a multi_array could be created by passing a reference to anything that fullills he requirements of a multi_array. That seems not to be the case. If you could pont me to any additional information on this library, I would be interested. Robert Ramey

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(Semi-)Automatic Resoning Tools
by Hossein Haeri 06 Apr '06

06 Apr '06

Dear all, Off-hand, I know that there is no such a thing in the Boost repository: a (semi-)automatic reasoning tool. Or, am I missing anything? I have made a short google on that, and the first thing comming up is ACL2 which is quite huge for my purpose. The problem with it is that it takes much longer to become an effective user of it than the time I've got. So, does anybody here know any such reasoning tool which doesn't need that much learning time? TIA, --Hossein ___________________________________________________________ Yahoo! Photos NEW, now offering a quality print service from just 8p a photo http://uk.photos.yahoo.com

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Re: [Boost-users] Idea for equation library
by Stephen Henry 06 Apr '06

06 Apr '06

It's quite a nice idea, but I'm not too sure why anyone would want to use it. There are already a number of optimised and fully featured mathematical libraries out there. Without somesort a capability for algebraic manipulation, for example, the ability to determine the value of a variable within an equation given a number of relations (which coincidently would be really useful, but non-trivial to implement), the library basically amounts to some santatic sugar. What I find interesting, however, is the named associations for function arguments ( x -> 5 ), for example, but I think there is already a library in Boost that enables such functionality. S. -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Stephen Gross Sent: 04 April 2006 18:29 To: Boost Subject: [Boost-users] Idea for equation library I've got an idea for a toolkit that uses boost::lambda to let you write 'equations' on the fly in c++. For instance, consider the following pseudo-code: ================== Equation e = x + y; print e(x -> 5, y -> 10) // Prints 15 e = x - y print e(x -> 5, y -> 10) // Prints -5 Equation d = eq(e) + z print d(x -> 1, y -> 2, z -> 3) // Prints 2 ================== The idea is that you can encapsulate an algebraic function in a standalone 'Equation' instance, and dynamically reassign that equation. It's built off of boost::lambda (of course), but it lets you name the variables rather than just refer to them with the standard placeholders (_1, _2, etc.). Is it worthwhile for me to post the toolkit code on this group? Thanks, --Steve Stephen Gross Case Western School of Medicine Cleveland, OH "By Grabthar's hammer, by the sons of Worvan, you shall be avenged." - Dr. Lazarus _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Re: [Boost-users] equation (really expression) idea
by james.jones＠firstinvestors.com 06 Apr '06

06 Apr '06

From: "Stephen Gross" <sgross(a)darwin.epbi.cwru.edu> > >1. Types are not template-ized. I don't want everything to be a double. > This is an interesting point. My goal so far has been to prioritize > simplicity above all. The purpose of the toolkit is for letting people write > arithmetic equations easily. In light of that, I think sticking with doubles > makes sense. So if I want to use a rational class, or a higher-precision double provided by a library, or a fixed-precision class, or a boolean type (a la Excel: if(x<y,x,y)) I'm out of luck? I appreciate simplicity of use, but you can still accomplish this by letting double be the default type (which makes sense, I think). Then non-power-users get double all the time, and power users can still do some hacking. > Well, this is an interesting idea but it runs contrary to the metaphor I > want. In the above example, the variables 'x' and 'y' work as global > variables. I want the user to have to pass x and y directly to the equation. I agree - which is why I wrote the bit about an evaluate function that takes positional arguments. Maybe named arguments are even better, though. I hadn't thought of that. > If you had global-level variables, then it would be difficult to make the > above example work properly (passing z on as x and y when f2 invokes f1).. Please don't call them globals - they aren't. They're in the same scope as the expression. However, as to your particular issue, this isn't a problem: variable x, y, z; expression expr1 = x + y; expression expr2 = z + expr1; A variable is just a special form of an expression, after all. As to mapping, it would be nice to be able to write code like: double v = expr1(x=5,y=10); double w = expr2(x=2,y=3,z=8); I should think the Boost parameter library could handle this. Actually, maybe you don't even need the Boost parameter library. Just define operator() on expression to ignore its arguments (then x=5, y=10 sets the values of x and y, and expr1 is then evaluated in that context). - James

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Cross compiling to Arm.
by James Hughes 06 Apr '06

06 Apr '06

Hello all, Just quick question. Has anyone managed to cross compile Boost from a Linux X86 host to ARM using a gcc compiler? Is so, which version of the compiler did you use and which version of boost? I am having problems with iwmmxt_le-g++ v 3.4.3 and boost:1.33.1, in the Spirit libs (as previously posted). It appears to be a compiler fault...which is not evident inthe non-cross compiler version of g++ 3.4.3. James

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