- Boost - lists.boost.org

[config] BOOST_STL_SUPPORTS_NEW_UNICODE_LOCALES macro?
by Antony Polukhin 07 Apr '12

07 Apr '12

Hi, I'm interested in preprocessor macro, that provides info about std::locale() usability with char16_t and char32_t character types. Currently, some compilers provide new Unicode character types, but calls to std::locale() generate runtime error. I'd like to use that macro to: * provide compile time errors instead of runtime errors * enable/disable some Boost.Lexical_cast tests. Another useful macro would be BOOST_UNICODE_FULL_SUPPORT. It can be defined like this: #if !defined(BOOST_NO_CHAR32_T) \ && !defined(BOOST_NO_CHAR16_T) \ && !defined(BOOST_NO_UNICODE_LITERALS) \ && defined(BOOST_STL_SUPPORTS_NEW_UNICODE_LOCALES) #define BOOST_UNICODE_FULL_SUPPORT #endif -- Best regards, Antony Polukhin

1 0

Re: [boost] C++11 Metaprogramming
by Andrzej Krzemienski 06 Apr '12

06 Apr '12

> on Thu Apr 05 2012, Andrzej Krzemienski <akrzemi1-AT-gmail.com> wrote: > >> For the end users of meta-programming library (at least those interested in >> type transformations), I believe that alias templates offer a significant >> improvement to the interface: >> http://akrzemi1.wordpress.com/2012/03/19/meta-functions-in-c11/ > > Yeah... I started doing a bunch of that, but I am not yet convinced it's > an overall improvement. One thing you emphatically *don't* get with > that formulation is lazy evaluation. remove_pointer<int> is valid until > you instantiate it but RemovePointer<int> is not, and the former is > often quite useful. Also, you can't use metafunction forwarding—which > also eliminates vast amounts of typing—with RemovePointer. Also, you > end up needing to define more names than you otherwise would (e.g. both > remove_pointer and RemovePointer). My standard approach when doing this > has been to name them remove_pointer_ and remove_pointer, so at least > they have an obvious and mechanical relationship. I guess my understanding of the name "meta-programming" might be a bit different, and term "end user" might have been too much a mental shortcut, but let me share my view of someone that doesn't want to go to deep into the meta-programming but still needs to use the simple forms thereof (like type traits). This is a somewhat simplified version of what I was facing recently. I need a function that perfect-forwards the argument but returns by value: template <class T> T fun(T&& v); The above is incorrect, because T may be deduced to be an lvalue reference. But be sympathetic, perfect-forwarding is already hard enough to acquire. I need type trait std::decay: template <class T> std::decay<T> fun(T&& v); But this does not work! I forgot "::type". Let's try again: template <class T> std::decay<T>::type fun(T&& v); No. It still doesn't work. And this is the worst part: I forgot the "typename". Having to type this "typename" is really terrible and just scares off many people. If you do not mind it, it only means that you got used to it; but people should not be forced to get used to too many gotchas. Alias templates offer a simplification that can improve the "teachability" of type traits. You may not consider type traits a proper meta-programming, and all I say might be a bit off topic. But if we had these alias templates for type traits, it looks to me, it would make a soft introduction to meta-programming for the newbies. Regards, &rzej

3 2

Re: [boost] C++11 Metaprogramming
by Andrzej Krzemienski 05 Apr '12

05 Apr '12

> I am on the C++Now 2012 schedule giving a talk on metaprogramming in > C++11, which is really just supposed to be an overview of the state of > the art. I am just at the beginnings of my research for this > presentation, having learned a few things and done a few experiments, > and it seemed to me foolish not to ask the Boost community for its > insights. I'm sure y'all have come up with many neat tricks and > techniques. If you'd care to share them here, that would be much > appreciated. For the end users of meta-programming library (at least those interested in type transformations), I believe that alias templates offer a significant improvement to the interface: http://akrzemi1.wordpress.com/2012/03/19/meta-functions-in-c11/ Regards, &rzej

4 5

Belgium C++ Users Group
by Francisco Almeida 05 Apr '12

05 Apr '12

Hello to all, I just subscribed to this mailing list to ask the Boost developer community for anyone actively working on new libraries/library refactoring if they would be interested in presenting to us a lecture about the major changes Boost will undergo, now that the new C++ standard has been published and that support for it is quickly being implemented by the most popular compilers. Of course, assuming any generous Boost developer who happens to live/work in Benelux would be willing to visit us and share his/her experiences/ambitions with us. Best regards, Francisco Almeida

1 0

[type_traits] is_scalar - fit into register?
by Oliver Kowalke 05 Apr '12

05 Apr '12

Hi, is it a correct assumtion that all types which evaluate 'is_scalar<T>::value' to 'true' will fit into a processor register? Oliver

2 1

[math] Explicit message for configure checks
by Steven Watanabe 05 Apr '12

05 Apr '12

AMDG The attached patch just makes the output a little nicer. Okay to commit? In Christ, Steven Watanabe

2 1

boost::indeterminate and std::vector::emplace_back()
by Arno Schödl 04 Apr '12

04 Apr '12

Hi, there is a problem when using boost::indeterminate in conjunction with std::vector::emplace_back: std::vector<boost::tribool> v; v.emplace_back(boost::indeterminate); In VS2010, this code causes error C2383: '_Valty' : default-arguments are not allowed on this symbol The error occurs becasue emplace_back's _Valty template parameter is deduced as the type of boost::indeterminate which is a function with a default argument. What is the recommended way to explicitly create an "indeterminate" tribool value in cases like this? Regards, Arno -- Dr. Arno Schödl | aschoedl(a)think-cell.com Technical Director think-cell Software GmbH | Chausseestr. 8/E | 10115 Berlin | Germany http://www.think-cell.com | phone +49 30 666473-10 | US phone +1 800 891 8091 Amtsgericht Berlin-Charlottenburg, HRB 85229 | European Union VAT Id DE813474306 Directors: Dr. Markus Hannebauer, Dr. Arno Schoedl

2 1

[signals] [vc11] Compile Error (Ticket #1499)
by Joshua Boyce 04 Apr '12

04 Apr '12

The problem causing ticket #1499 is happening again under VC11. https://svn.boost.org/trac/boost/ticket/1499 Build scripts and logs: http://dl.dropbox.com/u/74751/cpp/boost/logs/msvc32-20120319-1118.bat http://dl.dropbox.com/u/74751/cpp/boost/logs/msvc64-20120319-1118.bat http://dl.dropbox.com/u/74751/cpp/boost/logs/msvc32-20120319-1118.txt http://dl.dropbox.com/u/74751/cpp/boost/logs/msvc64-20120319-1118.txt Bumping to check for _MSC_VER <= 1700 does the trick (tested locally). Patch: http://dl.dropbox.com/u/74751/cpp/boost/patches/signals-vc11-fix-20120319-1… Once this is applied the trunk compiles cleanly (well, no errors, there are still lots of warnings) using the VC11 beta. Thanks.

2 3

[propertymap] boost::function as map
by Frank Birbacher 03 Apr '12

03 Apr '12

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi! I've started working on supporting functors as property maps. I've just seen the commit r77506, with msg "Added function_property_map based on code from Philipp Moeller." So I guess I can stop working on that feature? Maybe regarding a boost::function as a property map all by itself (without make_function_property_map) is a good idea? My work is in ^/boost/sandbox-branches/birbacher/propertymap-functormap, BTW. Frank -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.17 (Darwin) Comment: GPGTools - http://gpgtools.org Comment: keyserver x-hkp://pool.sks-keyservers.net iEYEARECAAYFAk97a0oACgkQhAOUmAZhnmo/qgCcDv19D3TfjW0nLb0hiykSwrzL yfQAnjvTSJv3MZMgBCFS1mGJQKFfDBYO =HCjT -----END PGP SIGNATURE-----

2 1

[preprocessor] PUSH_BACK/_FRONT on empty array broken in 1.49
by Jan Boehme 03 Apr '12

03 Apr '12

Hi! BOOST_PP_ARRAY_PUSH_BACK & BOOST_PP_ARRAY_PUSH_FRONT on empty array leads to invalid code if Boost 1.49 is used. In 1.48 and older it works as expected. An incident was already filed and a sample attached: https://svn.boost.org/trac/boost/ticket/6760 Thanks for solving. Let me know if I can be of further assist. Jan

2 2