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[type_traits] is_complete<T> possible realization
by Antony Polukhin 09 Nov '12

09 Nov '12

Hi, Yesterday I had a need to detect, is class forward declared or is it complete. Here are some thoughts: template <class T, int Misc> struct is_complete { typedef char false_type; typedef int true_type; template <class T1> static typename boost::enable_if_c<sizeof(T1), true_type>::type test(int); template <class T1> static false_type test(...); enum ENU { value = ( sizeof(test<T>(0)) == sizeof(true_type) )}; }; 'Misc' parameter is required to work around compilers one time instantiation: struct incomplete; template <int N> struct incomplete_template; struct complete{}; struct complete_abstract{ virtual void foo() =0; }; void test(); void foo1() { cout << is_complete<incomplete, __LINE__>::value << is_complete<incomplete_template<0> , __LINE__>::value << is_complete<incomplete_template<1> , __LINE__>::value << is_complete<complete, __LINE__>::value << is_complete<complete_abstract, __LINE__>::value << endl; } struct incomplete{}; template <> struct incomplete_template<0>{}; void foo2() { cout << is_complete<incomplete, __LINE__>::value // Without second template parameter it would be still returning 0 << is_complete<incomplete_template<0> , __LINE__>::value << is_complete<incomplete_template<1> , __LINE__>::value << is_complete<complete, __LINE__>::value << is_complete<complete_abstract, __LINE__>::value << endl; } int main() { foo1(); // Outputs 00011 foo2(); // Outputs 11011 return 0; } I was thinking of changing 'Misc' parameter definition to something like this: template <class T, class... Misc> struct is_complete ; Than it can be used in template functions/classes just like this: template <class T, class... SomeClasses> void test_function() { is_complete<T, SomeClasses..., boost::mpl::int_<__LINE__> >::value; } So, Is there interest in such metafunction? Can somebody give advices how to improve it? (I`m not sure that implementation is portable, I`ve tested it only on GCC-4.6 and CLANG-3.0, MSVC compiler will be available only tomorrow) -- Best regards, Antony Polukhin

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Re: [boost] hierarchy_tree container
by Morgan Freeberg 09 Nov '12

09 Nov '12

> Subject: Re: [boost] hierarchy_tree container > On Tue, Nov 6, 2012 at 5:28 PM, Morgan Freeberg <mkfreeberg(a)hotmail.com> wrote: > > I have the logic for this nicely separated into a header that seems to meet all the Boost coding guidelines, although I know a peer review process would likely yield helpful improvements that aren't immediately obvious to me. The doc file I prepared goes into much greater detail how this all works...would there be interest in looking into such a thing? > > > yes, can you share the doc url ? > http://www.peekinthewell.net/boostsub/hierarchy_tree/

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[datetime] IANA Time Zone Database
by Maxim Yegorushkin 09 Nov '12

09 Nov '12

Hi Boost, I have files with timestamps in various timezones. I would like to be able to convert these timestamps, no matter what timezone they are in (I know the names of the timezones) to UTC timestamps. I looked through datatime library documentation and found date_time_zonespec.csv database which doesn't seem to support the notion of different rules for the same timezone depending on the date. For example, Russia used to have summer time but not any more. Another method seems to be passing a timezone specification string manually, which requires the user to figure what it should be for a particular date. In other words, given a timestamp and its timezone, I would like to be able to convert that timestamp into a UTC timestamp using conversion rules in force at that particular date in the past. Ideally, this would use IANA Time Zone Database or something similar. Is there a facility in boost to do just that? -- Maxim

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C++ announcements coming tomorrow
by Beman Dawes 09 Nov '12

09 Nov '12

Herb Sutter, the Convenor of the ISO C++ Standards Committee, will be making some announcements tomorrow likely to be of interest to C++ developers in general and Boosters in particular. The venue is a talk titled "The Future of C++" at the Microsoft Build Conference. While some of Herb's announcements will be specific to Microsoft, the key C++ initiatives involve Boost and the whole C++ community. Some of the ideas evolved from feedback Herb got at C++Now/BoostCon 2012 last May. I'll post a summary of the announcements tomorrow, but you can also watch the live stream at http://channel9.msdn.com at 12:45 PM Pacific time. For other time zones, see http://www.timeanddate.com/worldclock/fixedtime.html?iso=20121102T1945 --Beman PS: We don't usually post teasers like this on the Boost lists, but Herb asked that a notice be posted, and given the endless work he has put in on this over the summer, I couldn't say no.

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★ Boost, Bruce left a message for you
by Badoo 08 Nov '12

08 Nov '12

Bruce left a message for you Only you can see the sender and content of your message, and you can delete it anytime. You can instantly reply using our message exchange system: http://eu1.badoo.com/tortoise74/in/3i4doZuulPE/?lang_id=3&m=21&mid=509c4330… If the link in this message does not work, try copying and pasting it into your browser. This email is part of our delivery procedure for the message sent by Bruce. If you have received this email by mistake, please ignore it. The message will be deleted soon. Have fun! The Badoo Team You have received this email from Badoo Trading Limited (postal address below). http://eu1.badoo.com/impersonation.phtml?lang_id=3&email=boost%40lists.boos… Badoo Trading Limited is a limited company registered in England and Wales under CRN 7540255 with its registered office at Media Village, 131 - 151 Great Titchfield Street, London, W1W 5BB.

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[test]portability of data test cases and build issues
by Gennadiy Rozenal 08 Nov '12

08 Nov '12

Hi, I've been working on portability fixes for new features in boost.test. They now works fine with gcc 4.6 and 4.7 msvc-10.0 and msvc-11.0. My attempt with clang on linux lead to compiler crashing, but I see it passing in regression on darwin, so I am not sure on the status. I do still have some issues about portability and boost.build: 1. Boost.Build does not handle correctly target foo with sources residing in subdirectory foo under location of Jamfile. I had to rename directory boost/libs/test/test/test_datasets into test_datasets_src, because of that. 2. How do I tell that I want to pass compilation to gcc in toolset gcc-4.7 only? I've tried <toolset>gcc-4.7:<cxxflags>-std=c++11 and <toolset>gcc-4.7.2:<cxxflags>-std=c++11 and either one does not work. <toolset>gcc:<cxxflags>-std=c++11 does work, but I want to pass different options for different versions of gcc. 3. Question: Should I tell *unconditionally* in Boost.Test Jamfile in boost/libs/test/build that I want to pass -std=c++11/-std=c++0x depending on a version? If not, how do I test test_dataset target with this option? Also How do I disable for configurations which does not support it? 4. Issues with regression testers setup? If you look here: http://www.boost.org/development/tests/trunk/developer/test.html You will see that: a) clang linux columns are empty. Why is that? b) msvc-11.0 setup is broken because of: 'cl' is not recognized as an internal or external command, operable program or batch file. c) sun setup is broken because of: /bin/sh: line 2: CC: not found Can we fix these? 5. Portability for other compilers. I am not quite sure which is lowest version of gcc this feature works. Anyone who is interested in making it work with older/different compilers feel free to submit patches. Regards, Gennadiy

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Release branch closed
by Marshall Clow 08 Nov '12

08 Nov '12

Boosters, The release branch is now closed for all commits, except by explicit permission of release managers. -- The Release Managers, Beman Dawes Daniel James Eric Niebler Rene Rivera Vladimir Prus Marshall Clow

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[thread] warning in trunk
by Gennadiy Rozental 08 Nov '12

08 Nov '12

Hi, Can anyone clean this one: boost/thread/future.hpp(378) : warning C4913: user defined binary operator ',' exists but no overload could convert all operands, default built-in binary operator ',' used Gennadiy

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[OT] std::complex warts
by Neal Becker 08 Nov '12

08 Nov '12

std::complex doesn't seem to allow mixing of types in arithmetic operations. This is quite inconvenient for code that is generic on the base float type. For example: template<typename flt_t> flt_t some_function (std::complex<flt_t> z) { return 2. * z / 4.2 + ... } This will fail to compile when flt_t == float (but succeeds for double). casting every constant in a large computation is really not an acceptable option. Thoughts?

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[type_traits] is_convertible<int, int&> inconsistent result
by TONGARI 08 Nov '12

08 Nov '12

Hi, I'd expect boost::is_convertible<int, int&>::value to be false, so I was surprised that it gives me "true" under g++ 4.7.1. Switch to std::is_convertible<int, int&> or using clang instead gives me the expected "false". After some search, I found: https://svn.boost.org/trac/boost/ticket/7251 Any plan to fix it?

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