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[mpl] struct definition and mpl sequence in one shot?
by Adam Romanek 03 Oct '14

03 Oct '14

Hi! This is a re-post from the boost-users mailing list. I have a problem and I'm not sure how to approach it. Currently my code looks like this: struct Definition { typedef boost::mpl::int_<5> A; typedef boost::mpl::int_<3> B; typedef boost::mpl::int_<6> C; typedef boost::mpl::int_<1> D; typedef boost::mpl::vector<A, B, C, D> Seq; }; Here, the number N in mpl::int_< N > denotes some arbitrary decimal number. Then some other code calculates the sum of these numbers up to the type defined by "key", e.g. for Definition::D, the sum is 5 + 3 + 6 (A + B + C). This needs to be done at compile-time. That's why I use mpl::vector and some appropriate meta-programming. I'm wondering whether it would be possible to provide such struct definition without the need to repeat type names in the mpl::vector for Seq type. In other words, I'd probably need a bunch of macros which would allow me to write code like this: struct Definition { FIELD(A, 5); FIELD(B, 3); FIELD(C, 6); FIELD(D, 1); GEN_SEQ() // if needed }; And then Definition::A would still refer to boost::mpl::int_<5>, or would at least allow me to access the boost::mpl::int_<5> somehow, and Definition::Seq would give me the appropriate MPL sequence. Of couse this is just my imagination. The code might look different, I'm just looking for options. Thanks in advance. Adam Romanek

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[Boost] [DateTime] dividing a time_period in N time_periods
by Pablo Madoery 02 Oct '14

02 Oct '14

Hi, I want to make a method which divides a time_period in N time periods, something like this: list<time_period> splitTimePeriod(time_period timePeriod, int n); I actually have made it and although it seems to work it results very inefficient regarding the time it took to divide a large time_period. The method I did is this: list<time_period> splitTimePeriod(time_period timePeriod, int n) { double secsTime = dateTime::diffSeconds(timePeriod.end(), timePeriod.begin()); // tiempo en segundos de cada período de tiempo double ti = secsTime / n; list<time_period> timePeriods; // tiempo de comienzo del primer período de tiempo ptime tpBegin = timePeriod.begin(); // tiempo de fin del último período de tiempo ptime tpLastEnd = timePeriod.end(); for (int i = 0; i < n; i++) { int tUnits = ti * time_duration::ticks_per_second(); // tiempo de comienzo del siguiente período de tiempo ptime tpNextBegin = dateTime::increment(tpBegin, tUnits); // tiempo de fin del período de tiempo ptime tpEnd; if (i == n - 1) { tpEnd = tpLastEnd; } else { tpEnd = dateTime::decrement(tpNextBegin, 1); // guarda para evitar que por cuestiones // de redondeo, el tiempo final de un período // sea mayor que el pasado inicialmente // como argumento de entrada if (tpEnd > tpLastEnd) { tpEnd = tpLastEnd; } } time_period p(tpBegin, tpEnd); // se inserta período de tiempo en la lista timePeriods.push_back(p); // se actualiza el comienzo del siguiente período de tiempo tpBegin = tpNextBegin; } return timePeriods; } Other methods I use are these: double diffSeconds(const ptime &dateA, const ptime &dateB) { time_duration diff = dateA - dateB; return diff.total_seconds(); } ptime increment(const ptime &date, int n) { time_iterator it(date, dateTime::unit); for (int i = 0; i < n; i++) { ++it; } return *it; } ptime decrement(const ptime &date, int n) { time_iterator it(date, dateTime::unit); for (int i = 0; i < n; i++) { --it; } return *it; } const time_duration unit = microseconds(1); ################################################# The question is: is there a better way to accomplish this?

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[static_if] Is there interest in a `static if` emulation library?
by Lorenzo Caminiti 01 Oct '14

01 Oct '14

Hello all, With C++14 generic lambdas, it is possible to implement a sort of `static if` (see also N3613): template< typename T > void assign ( T& x, T const& y ) { x = y; static_if<boost::has_equal_to<T>::value>( std::bind([] ( auto x, auto y ) { assert(x == y); std::cout << "asserted for: " << typeid(T).name() << std::endl; }, x, y) ).else_( [] ( ) { std::cout << "cannot assert for: " << typeid(T).name() << std::endl; } ); } The bind around the generic lambda is a bit verbose... but this code compiles, asserts when called on int, and does not assert when called on x_t (tested on clang 3.4.2): int i = 1; struct x_t { } x; assign(i, i); // asserts assign(x, x); // does not assert I have attached a reference implementation. Thank you. --Lorenzo P.S. I didn't do much background research... sorry if this topic has already been considered and discussed in Boost.

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[uuid] Issue 9407: help required to merge fix
by Antony Polukhin 01 Oct '14

01 Oct '14

There is an issue with long history https://svn.boost.org/trac/boost/ticket/9407 That issue is annoying and can be easily fixed. There's even a pull request to fix that issue (https://github.com/boostorg/uuid/pull/2) Could someone take a look at the pull request, comment it and even merge to develop branch? -- Best regards, Antony Polukhin

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Licensing issue (TestCmd.py)
by Polhodzik Peter (ext) 01 Oct '14

01 Oct '14

Hi all, Could anyone tell me, why the \boost_1_38_0\tools\build\v2\test\TestCmd.py (TestCmd version 0.02) file in Boost 1.38.0<http://www.boost.org/users/history/version_1_38_0.html> has Steven Knight's Python license reference, this: # Copyright 2000 Steven Knight # This module is free software, and you may redistribute it and/or modify # it under the same terms as Python itself, so long as this copyright message # and disclaimer are retained in their original form. # # IN NO EVENT SHALL THE AUTHOR BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, # SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF # THIS CODE, EVEN IF THE AUTHOR HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH # DAMAGE. # # THE AUTHOR SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A # PARTICULAR PURPOSE. THE CODE PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, # AND THERE IS NO OBLIGATION WHATSOEVER TO PROVIDE MAINTENANCE, # SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. __author__ = "Steven Knight <knight(a)baldmt.com<mailto:knight@baldmt.com>>" __revision__ = "TestCmd.py 0.D002 2001/08/31 14:56:12 software" __version__ = "0.02" while the original TestCmd 0.02<http://baldmt.com/Test-Cmd/Archive/Test-Cmd-0.02.tar.gz> is Perl licensed, this way: COPYRIGHT Copyright 1999-2000 Steven Knight. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. ? It is also unclear which Python or Perl license it refers to ,since there are more licenses versions for both. I know 1.38.0 is an old release, but now I definitely need to have the information about this one. Updating to 1.56.0 is NOT an option to solve the problem this time. Thank you!! Üdvözlettel / Best Regards, Péter POLHODZIK OSS Expert [cid:image001.jpg@01CFDD70.90958F30] Phone: +36 (46) 5-17894 Fax: +36 (46) 5-17801 Peter.Polhodzik.ext(a)evosoft.com<mailto:Peter.Polhodzik.ext@evosoft.com> evosoft Hungary Kft. Arany János tér 1. H-3508 Miskolc www.evosoft.com<http://www.evosoft.com/> ---------------------------------------------------

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[move] Build failures in develop
by Andrey Semashev 01 Oct '14

01 Oct '14

Hi, I'm seeing lots of build errors that originate from Boost.Move, such as: In file included from ../libs/log/src/text_file_backend.cpp:41: In file included from ../boost/filesystem/path.hpp:28: In file included from ../boost/iterator/iterator_facade.hpp:12: In file included from ../boost/iterator/interoperable.hpp:11: In file included from ../boost/mpl/or.hpp:23: ../boost/mpl/aux_/nested_type_wknd.hpp:27:10: error: no type named 'type' in 'boost::move_detail::is_rv<boost::rv<boost::log::v2_mt_posix::aux::light_function<void ()> > >' : T::type ~~~^~~~ See the full error logs: http://www.boost.org/development/tests/develop/developer/output/marshall-ma… http://www.boost.org/development/tests/develop/developer/output/teeks99-08b… http://www.boost.org/development/tests/develop/developer/output/teeks99-tes… I didn't change Boost.Log for quite some time, so there seems to have been some breaking change. Could this be fixed?

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[thread] Build failures in develop
by Andrey Semashev 01 Oct '14

01 Oct '14

Hi, Boost.Thread currently fails to build on MSVC, which affects other libraries: http://www.boost.org/development/tests/develop/developer/output/teeks99-08d… Could it be fixed?

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[modularization] request for a new modularization status for develop branch
by Vicente J. Botet Escriba 01 Oct '14

01 Oct '14

Hi Peter, could you upload a new modularization status, as in http://www.pdimov.com/tmp/report-d53f656/module-levels.html ? Best, Vicente

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[Modularization][optional][functional] boost::none - what do we want it to be?
by Andrzej Krzemienski 30 Sep '14

30 Sep '14

Hi Everyone, I know it may be premature to to think about removing every cycle in Boost, but while looking at the cycle reports I found that at least one library is using boost::none, for a purpose different than indicating an uninitialized boost::optional. It is in Boost.Functional: https://github.com/boostorg/functional/blob/master/include/boost/functional… It uses none_t as a default type for a template type parameter Allocator. My question is: what do we want boost::none_t to indicate, at least in Boost? 1. A value-semantic alternative to void, that anyone can use? 2. A tag indicating boost::optional<T> without a value? The answer to this question dictates how we should untie the cycle. I know it is too soon to care about small cycles right now, but my question is more about "the principles". Regards, &rzej

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"Easy Build and Install" fails at bootstrap.sh
by Josh Juran 30 Sep '14

30 Sep '14

I'm building Boost from Git since there's no secured download option, only HTTP. josh@alice:~/src/boost$ git log --oneline -n1 43bb782 Update thread from master. josh@alice:~/src/boost$ ./bootstrap.sh ./bootstrap.sh: 1: ./bootstrap.sh: ./tools/build/src/engine/build.sh: not found Building Boost.Build engine with toolset ... Failed to build Boost.Build build engine Consult 'bootstrap.log' for more details josh@alice:~/src/boost$ cat bootstrap.log ./bootstrap.sh: 218: cd: can't cd to ./tools/build/src/engine Do I need to run git-submodule? It would be helpful if Getting Started covered this. Josh

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