January 2008 - Boost - lists.preview.boost.org

Facebook update.
by Jan 17 Jan '08

17 Jan '08

We now have 80 members on facebook, this can serve as a good recruiting ground for new C++ talent. Boost/C++ group on facebook: http://www.facebook.com/group.php?gid=4200526117 Thanks

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[Accumulators] Documentation
by Edward Diener 17 Jan '08

17 Jan '08

Attempting to build accumulators documentation from the latest SVN head by executing bjam from the /boost/libs/accumulators/doc directory yields: error: Unable to find file or target named error: 'object(file-target)@476' error: referred from project at error: /E:/Programming/VersionControl/Subversion/Boost/tools/quickbook'

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Boost.Tests: Unit test defines own main() function, why?
by Jens Seidel 17 Jan '08

17 Jan '08

Hi, I would like to know why Boost's unit test framework requires that the user defines init_unit_test_suite(int, char**) (or with char *[] argument???) instead of main(). I recently had again some trouble because of it: * It broke the general autoconf test in boost.m4 as the existance of a Boost library can normally easily be tested by using boost code in main() and not init_unit_test_suite(). (Will probably be fixed soon in boost.m4.) * According to http://lists.boost.org/Archives/boost/2007/05/121601.php linkers don't look into libraries (either static or dynamic) to find main so that unit tests cannot be cimpiled as shared library. * I noticed that Debian's Boost library doesn't work for me as main() is not found in the shared library (but in the static one). I found now beside my bug report http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=456863 also http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=432921 which mainly refers to the link above. I'm not sure whether my problem is an error in Debian's packages or not but I ask why is main handled differently in Boost.test? Wouldn't it be sufficient to ask the user simple to start init_unit_test_suite() from a user specified main() to make most problems go away? Maybe it would be even OK to just start init_unit_test_suite() in the constructor of a static variable (yes, I know that the initialisation order may cause trouble with other static data). http://www.boost.org/libs/test/doc/faq.html doesn't explain it! I will now use ifdef's to easily allow using boost/test/included/unit_test.hpp as alternative to the library. Jens

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[interest] Egg, function object builders and adaptors
by shunsuke 17 Jan '08

17 Jan '08

Hi, all. In a recent discussion, a library named Egg possibly left a good impression on boosters, so I propose it. Introduction: It is not so easy to define FunctionObjects especially if you want to support Boost.ResultOf and Boost.Lambda. Therefore, as Boost provides iterator_facade and iterator adaptors, Egg provides function_facade and function adaptors. Egg provides the following features: * Helpers to build FunctionObject: * egg::function and egg::function_facade provides the way to build FunctionObject which supports Boost.ResultOf and Lambda. * FunctionObject Adaptors(in other words, higher-order functions): * egg::curryN supports the currying. * egg::pipable emulates extension methods(C#). * egg::fuse emulates variadic templates in very limited way. * etc... The zipped source code is in Vault/FunctionObjects: http://tinyurl.com/34lgda The document is on line: http://p-stade.sourceforge.net/boost/libs/egg/ svn repository: https://p-stade.svn.sourceforge.net/svnroot/p-stade/trunk/boost Tested under: trunk and Boost1.34.1. An example of currying in Egg: int plus(int x, int y) { return x + y; } typedef result_of_curry2<int (*)(int, int)>::type T_curried_plus; T_curried_plus const curried_plus = BOOST_EGG_CURRY2(&::plus); void test() { BOOST_CHECK( curry2(&::plus)(4)(9) == 13 ); BOOST_CHECK( curried_plus(4)(9) == plus(4, 9) ); BOOST_CHECK( uncurry(curry2(plus))(4, 9) == 13 ); } If interested enough, it might be enqueued to the review queue. Anyway, comments are most welcome. Regards, -- Shunsuke Sogame

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Re: [boost] Boost.Tests: Unit test defines own main() function, why?
by Vectra17 17 Jan '08

17 Jan '08

This code needed #define BOOST_TEST_DYN_LINK and now works perfectly. Well almost perfectly, before I realised something rather strange: the compiler ask for a .LIB as well. I am sure it exectues the DLL because when I erase it, the program crashes(.dll not found). So why is the compiler still asking for a .LIB file when I specifeid DLL linking? -- View this message in context: http://www.nabble.com/Boost.Tests%3A-Unit-test-defines-own-main%28%29-funct… Sent from the Boost - Dev mailing list archive at Nabble.com.

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Re: [boost] Is there any interest in a template geometry library?
by artemp 17 Jan '08

17 Jan '08

Barend Gehrels wrote: > > Is there any interest in a template geometry library? > I'm very interested! --Artem http://mapnik.org -- View this message in context: http://www.nabble.com/Is-there-any-interest-in-a-template-geometry-library-… Sent from the Boost - Dev mailing list archive at Nabble.com.

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wave lexed_tokens sample gives an unexpected answer
by Leo Davis 17 Jan '08

17 Jan '08

Hello, I built the Wave preprocessing lib out of CVS head today using GCC 4.2.1 on Linux x86 box (openSUSE 10.3). I then built the lexed_tokens sample and ran it on the attached header file. The unexpected answer was how the 'defined' keyword was treated. I expected it to treat it as T_DEFINED, but it seems to return T_IDENTIFIER as shown by this output fragment: ... PP_IF (#370) at foo.h ( 4/ 1): >#if< SPACE (#393) at foo.h ( 4/ 4): > < IDENTIFIER (#381) at foo.h ( 4/ 5): >defined< SPACE (#393) at foo.h ( 4/12): > < IDENTIFIER (#381) at foo.h ( 4/13): >BAR< NEWLINE (#395) at foo.h ( 4/16): >\n< ... Leo #ifndef FOO_H #define FOO_H #if defined BAR #define BAZ #endif #endif /* FOO_H */

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Globally Unique Identifier library by Andy Tompkins ?
by Janek Kozicki 16 Jan '08

16 Jan '08

Hello, I wasn't following boost development for about 8 months, now I'm slowly getting back on track (about 4000 unread emails had accumulated in my inbox, gotta look through them ;) I just looked at http://www.boost.org/more/formal_review_schedule.html and I didn't see any information about the mini review for Andy's library. Is it scheduled, was it already done, is it accepted? What's the status? best regards -- Janek Kozicki |

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Re: [boost] Terminology:Type Unification? (was Re: RFC Generic data structure traversal / manipulation library
by dan marsden 16 Jan '08

16 Jan '08

Larry Evans wrote: >Page: > >http://spirit.sourceforge.net/dl_docs/traversal/html/traversal/quick_start_… > >contains a section titled: > >Type Unification > >however, it appears like what it describes is more like the stl's >accumulate or mpl's fold. Could you explain the reason for the >title and why a title using accumulate or fold wouldn't be >more intuitive to readers? The terminology is taken from the paper by Ren and Erwig, in the references section. I've borrowed a lot of the naming conventions and terminology from this paper. In the original there are 2 traversal types, type preserving which return a result of the same type as their input argument, and type unifying, which take all input types to the same (fixed) output type. In my library, I've currently replaced the type preserving traversals with inplace traversals, as C++ suits modification in place better than large amounts of copying. The 2 numbered points at the start of the Type Unification section attempt to explain this, but obviously this could be clearer. I'll have a look at rewording things. The operation is certainly not a fold, so I think it would be misleading to associate the example with fold like terminology. Cheers Dan ___________________________________________________________ Yahoo! Answers - Got a question? Someone out there knows the answer. Try it now. http://uk.answers.yahoo.com/

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[utility] initialized_value - a convenience class for value_init.hpp
by Niels Dekker - mail address until 2008-12-31 16 Jan '08

16 Jan '08

For the convenience of the end users, I would like to add a little class to value_init.hpp, called initialized_value, having a conversion operator as its one and only member. Because it's just an extra feature of value_init, and Fernando Cacciola (the owner of value_init) already agrees that this class is a useful addition, I don't think an officially review of the class is necessary. But please tell me if you think otherwise. Details: The following syntax should initialize an object in a generic way, assuming that its type T is CopyConstructible: T obj1 = T(); Unfortunately this object may *not* be initialized properly, because of value-initialization related compiler issues of various C++ implementations, including MSVC, Borland, and GCC. (Boost ticket #1217, #1459, and #1491.) Fernando Cacciola and I have recently reimplemented boost::value_initialized, to work around those issues. (value_init.hpp, release branch, changeset [42501].) So the next release version of boost::value_initialized can be used to properly initialize an object, even in the presence of those compiler issues, as follows: T obj2 = get( value_initialized<T>() ); Still this way of initializing an object is rather verbose, and it has a form of code duplication, because it mentions the type of the object (T) twice. Within user code, the type may of course look more like Namespace::Template<Arg>::Type. Therefore I would like to add a class, boost::initialized_value, supporting the following: T obj3 = initialized_value(); The class would be implemented as follows: namespace boost { class initialized_value { public : template <class T> operator T() const { return get( value_initialized<T>() ); } }; } Its conversion operator would provide an appropriate value-initialized object for any CopyConstructible type T. Any comments are welcome. If it's okay, I would like to add it to the trunk version of value_init.hpp, next week. Kind regards, -- Niels Dekker http://www.xs4all.nl/~nd/dekkerware Scientific programmer at LKEB, Leiden University Medical Center

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