July 2012 - Boost - lists.preview.boost.org

Review Request: odeint
by Mario Mulansky 29 Aug '12

29 Aug '12

Hi, after getting some good amount of positive feedback on our talk at boostcon we are now asking for a formal review process of the odeint library, currently hosted on github: https://github.com/headmyshoulder/odeint-v2 odeint provides routines for numerically solving Ordinary Differential Equations, a task heavily required when approaching scientific problems numerically. In odeint we have implemented the most common algorithms in a modern, generic way which provides several advantages over existing implementations. The main focus of odeint is to separate algorithms from the underlying basic computation unit. This allows for example to easily use the power of modern GPUs via CUDA or OpenCL to speed up computational heavy simulations. Features: - provides most of the standard algorithms, including step size control, dense ouput and extrapolation routines - symplectic routines for Hamiltonian systems - implicit routines based on boost::ublas (MTL4 in progress) - high level integrate functions - interchangeable computation backend with existing bindings to CUDA and OpenCL - native support of ODEs defined for complex values - support of Boost.Units in most of the algorithms - support of arbitrary precision types The code is hosted on github: https://github.com/headmyshoulder/odeint-v2 Documentation/Tutorial: http://headmyshoulder.github.com/odeint-v2/doc/index.html We are, of course, looking for a review manager as well. Thanks! Karsten and Mario

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[multiprecision] Some rvalue reference experiments (performance inhancements #1)
by John Maddock 20 Aug '12

20 Aug '12

Folks, I've started to work through some of the points that came up in the multiprecision review, starting with further rvalue reference support. The idea (due to Marc Glisse) was to add operator overloads that look something like: Number&& operator+(Number&&a, const Number& b) { return static_cast<Number&&>(a += b); } Using my Polynomial Horner evaluation scheme as an example the number of temporaries dropped as follows: Type # temporaries No expression templates, no rvalue refs 24 No expression templates, rvalue refs 1 Expression template 0 Which is pretty impressive, but not necessarily typical usage, so by way of "real world" tests, I compared the times taken to evaluate Boost.Math's Bessel function test cases to 50 decimal places: Library Time/s # Allocations MPFR/mpreal (no ET's or rvalue refs) 9.4 13226029 MPFR/mpfr_class (ET's) 6.3 3948316 MPFR/mp_number(ET's) 6.0 2683646 GMP/mp_number(no ET's) 5.2 4186977 GMP/mp_number(ET's) 5.0 2594441 As you can see the number of allocations required when using mp_number with ET's turned off is almost double that without, I guess this is because many statements are similar to: a = b op c; Where a temporary is still required when relying on rvalue refs, but not for expression templates. Having said that the times are getting much closer now.... John.

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Is there any interest in getting pseudo random number generation using preprocessor at compile time into the Preprocessor library?
by Alexander Stoyan 20 Aug '12

20 Aug '12

The complete code, approach and efficiency proofs I described in my blog: http://alexander-stoyan.blogspot.com/2012/07/getting-pseudo-random-numbers-a t.html Need your opinion regarding the relevance and the approach correctness of the feature. Thank you in advance.

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[odeint] Iterator semantics
by Karsten Ahnert 19 Aug '12

19 Aug '12

Hi, we have posted a review request for odeint (a library for solving ordinary differential equations) on this list some days ago. An ODE is dx/dt = f(x(t)) and one is looking for the solution x(t) which is a function of t. Solving ODEs is usually an iterative task, so one starts with x(0) and iteratively applies a solver to obtain a discretized (and approximated) representation of the solution: x(0) -> x(dt) -> x(2*dt) -> x(3*dt) -> ... I played around with an iterator which is doing exactly this iterative procedure. For example, it can be used via odeint::runge_kutta4< state_type > stepper; // ode solver std::array< double , 3 > x = {{ 10.0 , 10.0 , 10.0 }}; // initial state double res = std::accumulate( // parameters : solver , ode , state , time , time_step make_const_step_iterator_begin(stepper, lorenz(), x, 0.0, 0.01) , make_const_step_iterator_end( stepper, lorenz(), x, 1.0, 0.01) , 0.0 , []( double sum, const state_type &x) { return sum + x[0]; } ); The first iterator increments the time until the time of the second iterator is rearched t=0.0 -> t=0.01 -> t=0.02 -> .. t=1.0 and the first component of the solution is accumulated. In principle, this approach works quite well, but there are some problems at least semantically. Maybe someone here has some comments or ideas on this: The defintion of this iterator is: template< class Stepper , class System , class StepperTag > class const_step_iterator : public boost::iterator_facade < const_step_iterator< Stepper , System , StepperTag > , typename Stepper::state_type const , boost::single_pass_traversal_tag > { ... }; It is a single pass iterator, so it can only check for equality of two iterators. This is problematic since equality here means that the time (t) of the begin iterator is smaller then the time of the end iterator. To ensure commutativity of the != or == operation I needed to flag the begin and end iterator explicitly. This is the reason for the two factory functions make_const_step_iterator_begin and make_const_step_iterator_end, which are doing this flagging. The second semantically problem is that the end iterator in principle does not need to know the stepper as well as the system (lorenz() in the above example). But all algorithms from the standard library and Boost.Range assume that the begin and end iterator are of same type. Therefore you have to put the stepper and the system into the end iterator too. Of course, there are techniques like type erasure which might solve this problem, but they introduce some run-time overhead which we want to avoid here. Any ideas or comments about this? P.S. The code can be found in the iterator branch in odeint: boost/numeric/odeint/iterator/const_step_iterator.hpp and some examples libs/numeric/odeint/examples/const_step_iterator.cpp git clone -b iterator git@github.com:headmyshoulder/odeint-v2.git

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[date_time] warning removal
by Vicente J. Botet Escriba 15 Aug '12

15 Aug '12

Hi, Attached a patch to remove most of the warnings below. Could I commit it? There are 4 warnings I want to check ../../../boost/date_time/period_formatter.hpp:117:47: warning: unused parameter 'separator' [-Wunused-parameter] ../../../boost/date_time/period_formatter.hpp:118:47: warning: unused parameter 'start_delim' [-Wunused-parameter] ../../../boost/date_time/period_formatter.hpp:119:47: warning: unused parameter 'open_end_delim' [-Wunused-parameter] ../../../boost/date_time/period_formatter.hpp:120:47: warning: unused parameter 'closed_end_delim' [-Wunused-parameter] where void delimiter_strings(const string_type& separator, const string_type& start_delim, const string_type& open_end_delim, const string_type& closed_end_delim) { m_period_separator; m_period_start_delimeter; m_open_range_end_delimeter; m_closed_range_end_delimeter; } and private: range_display_options m_range_option; string_type m_period_separator; string_type m_period_start_delimeter; string_type m_open_range_end_delimeter; string_type m_closed_range_end_delimeter; }; Is an assignment missing or it was a typo while trying to avoid the warning? Best, Vicente ../../../boost/date_time/date.hpp:194:55: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/date.hpp:195:67: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/date_duration.hpp:128:57: warning: extra ';' inside a struct [-pedantic] ../../../boost/date_time/date_duration.hpp:138:69: warning: extra ';' inside a struct [-pedantic] ../../../boost/date_time/date_duration.hpp:35:73: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/date_generators.hpp:37:30: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/date_generators.hpp:38:39: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/date_iterator.hpp:43:32: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/date_iterator.hpp:56:45: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/date_iterator.hpp:57:48: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/date_names_put.hpp:233:8: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/date_names_put.hpp:45:26: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/dst_transition_generators.hpp:21:38: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/local_time/custom_time_zone.hpp:46:7: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/local_time/custom_time_zone.hpp:47:40: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/local_time/local_date_time.hpp:211:31: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/local_time/posix_time_zone.hpp:118:39: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/period_formatter.hpp:117:47: warning: unused parameter 'separator' [-Wunused-parameter] ../../../boost/date_time/period_formatter.hpp:118:47: warning: unused parameter 'start_delim' [-Wunused-parameter] ../../../boost/date_time/period_formatter.hpp:119:47: warning: unused parameter 'open_end_delim' [-Wunused-parameter] ../../../boost/date_time/period_formatter.hpp:120:47: warning: unused parameter 'closed_end_delim' [-Wunused-parameter] ../../../boost/date_time/time_duration.hpp:254:57: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_iterator.hpp:22:77: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_iterator.hpp:33:45: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_iterator.hpp:34:48: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_iterator.hpp:35:64: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_iterator.hpp:36:65: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_iterator.hpp:37:66: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_iterator.hpp:38:65: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_iterator.hpp:39:64: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_iterator.hpp:40:65: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_zone_base.hpp:42:24: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/time_zone_base.hpp:43:33: warning: extra ';' inside a class [-pedantic] ../../../boost/date_time/wrapping_int.hpp:37:42: warning: extra ';' inside a class [-pedantic]

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C++11 decltype/SFINAE puzzler
by Eric Niebler 13 Aug '12

13 Aug '12

I'm running into a usability problem with the extended SFINAE rules that could effect best practice for all new C++ libraries. I'm hoping some clever person in the Boost community can help me. I find that in highly generic code, using decltype to define the return type of functions is very handy. Dave A. suggested a RETURNS macro to simplify this idiom: <https://groups.google.com/d/msg/boost-devel-archive/OzJ5Ft3pSnU/b_Ter9bgNqAJ> It's used like this: template<typename T> auto foo( T && t ) RETURNS( some-expression-using-t ); This is great and I use it a lot. Now, imagine you have a library of such functions calling other such functions: function A calls B calls ... calls Y, calls Z, all of which use decltype to declare their return types. Now, the user calls A passing a variable t for which the expression in Z's return type calculation makes no sense. Extended SFINAE kicks in, and Z simply disappears. Since Z has disappeared, the expression in Y's return type makes no sense, so Y disappears, too. And so on up the chain. The end result is that the user is presented with an error like: "no viable function A, template substitution failed." The user is given no information about which function in the chain failed to compile, or why. This is a serious usability problem! So, my question is: what can be done about this? Can we get the benefit of automatic type deduction in return types without causing SFINAE to drop functions from the overload set? Is there another trick we can use to report errors meaningfully when APIs are misused? The only solution I can think of is turn all the free functions in the chain into function objects and then using std::result_of to compute return types for them instead of using decltype directly. That means Dave's (very convenient!) RETURNS macro shouldn't be used, which is a bummer. (I think it also means that we need a noexcept_of template that computes the noexcept of an expression without causing the expression to appear in the function declaration, but that depends on how <http://llvm.org/bugs/show_bug.cgi?id=13286> gets resolved.) All suggestions welcome, -- Eric Niebler BoostPro Computing http://www.boostpro.com

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[graph] interest in resumable dijkstra?
by Alex Hagen-Zanker 13 Aug '12

13 Aug '12

Dear boost-list, I placed the BGL algorithm of the dijkstra_shortest_path in a class, with the creation and initialization part separate from the main algorithm. This allows interrupting, resetting and resuming the algorithm. Would this be of interest to anybody? The following function call: dijkstra_shortest_path(graph, orig, parameter_pack); is separated into: auto dijkstra = make_dijkstra(graph, parameter_pack); dijkstra.init_from_origin(orig /*, optional_visitor*/); dijkstra.expand(/*optional_visitor*/); The make_dijkstra() function reads all parameters from the parameter_pack including color_map and priority_queue Visitors interrupt the calculation using a do_intterrupt() callback instead of throwing an exception. The function expand() can be called repeatedly, each time with another visitor. The implementation requires C++11, because of auto and lambda's, it also relies on the following patch: https://svn.boost.org/trac/boost/ticket/7130. To see for yourself: http://people.pwf.cam.ac.uk/ahh34/dijkstra_test.zip I am interested to hear your opinion. With kind regards, Alex

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[1.51][Wave] Last minute commit
by Hartmut Kaiser 07 Aug '12

07 Aug '12

Hey, I would like to ask for permission to commit rev 79783 to the release branch (see attached patch). This fixes a bug introduced only recently and will fix the current regressions (see here: http://tinyurl.com/c44ql68, for instance). The patch is for Wave only and does not touch any of the other Boost libraries. Regards Hartmut --------------- http://boost-spirit.com http://stellar.cct.lsu.edu

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[review] Multiprecision review (June 8th - 17th, 2012)
by Jeffrey Lee Hellrung, Jr. 07 Aug '12

07 Aug '12

Okay, it's that time. Apologies for not sending a reminder, but there had been a lot of pre-review comments over the last week or so, so I think this has been on at least some people's radar. The original review announcement is given below. On Tue, May 29, 2012 at 2:08 PM, Jeffrey Lee Hellrung, Jr. < jeffrey.hellrung(a)gmail.com> wrote: > Hi all, > > The review of the proposed Boost.Multiprecision library authored by John > Maddock and Christopher Kormanyos has been scheduled for > > June 8th - June 17th, 2012 > > and will be managed by myself. > > From the Introduction: > > -------- > "The Multiprecision Library provides *User-defined* integer, rational and > floating-point C++ types which try to emulate as closely as practicable the > C++ built-in types, but provide for more range and precision. Depending > upon the number type, precision may be arbitrarily large (limited only by > available memory), fixed at compile time values, for example 50 decimal > digits, or a variable controlled at run-time by member functions. The types > are expression-template-enabled for better performance than naive > user-defined types." > -------- > > And from the original formal review request from John: > > -------- > Features: > > * Expression template enabled front end. > * Support for Integer, Rational and Floating Point types. > > Supported Integer backends: > > * GMP. > * Libtommath. > * cpp_int. > > cpp_int is an all C++ Boost licensed backend, supports both arbitrary > precision types (with Allocator support), and signed and unsigned fixed > precision types (with no memory allocation). > > There are also some integer specific functions - for Miller Rabin testing, > bit fiddling, random numbers. Plus interoperability with Boost.Rational > (though that loses the expression template frontend). > > Supported Rational Backends: > > * GMP > * libtommath > * cpp_int (as above) > > Supported Floating point backends: > > * GMP > * MPFR > * cpp_dec_float > > cpp_dec_float is an all C++ Boost licensed type, adapted from Christopher > Kormanyos' e_float code (published in TOMS last year). > > All the floating point types, have full std lib support (cos sin exp, pow > etc), as well as full interoperability with Boost.Math. > > There's nothing in principal to prevent extension to complex numbers and > interval arithmetic types (plus any other number types I've forgotten!), > but I've run out of energy for now ;-) > > Code is in the sandbox under /big_number/. > > Docs can be viewed online here: > http://svn.boost.org/svn/boost/sandbox/big_number/libs/multiprecision/doc/h… > -------- > Any review discussion should take place on the developers' list ( boost(a)lists.boost.org) and anyone may submit a formal review, either publicly to the entire list or privately to just myself. As usual, please consider the following questions in your formal review: 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? And, most importantly, please explicitly answer the following question: Do you think the library should be accepted as a Boost library? Lastly, please consider that John and Christopher have compiled a TODO list [1] based on pre-review comments. Feel free to comment on the priority and necessity of such TODO items, and whether any might be show-stoppers or warrant conditional acceptance of the library. Thanks in advance; looking forward to the discussion! - Jeff (& John & Christopher) [1] http://svn.boost.org/svn/boost/sandbox/big_number/libs/multiprecision/doc/h…

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[type_erasure] Review started (July 18-27, 2012)
by Lorenzo Caminiti 06 Aug '12

06 Aug '12

Hello all, *** The review of Steven Watanabe's proposed Boost.TypeErasure library begins on July 18, 2012 and ends on July 27, 2012. *** THE LIBRARY C++ provides runtime polymorphism through virtual functions. They are a very useful feature, but they do have some limitations. * They are intrusive. In generic programming, we can design an interface which allows third-party types to be adapted to it. * They require dynamic memory management. Of course, most of the problems can be avoided by using an appropriate smart pointer type. Even so, it still acts like a pointer rather than a value. * Virtual functions' ability to apply multiple independent concepts to a single object is limited. The Boost.TypeErasure library solves these problems allowing us to mirror static generic programming at runtime. Library source: http://svn.boost.org/svn/boost/sandbox/type_erasure/ Pre-built documentation: http://steven_watanabe.users.sourceforge.net/type_erasure/libs/type_erasure/ You can also download archives with pre-built documentation from: http://sourceforge.net/projects/steven-watanabe.u/files/ YOUR REVIEW Please submit a review to the mailing-list by replying to this email ("[boost] [type_erasure] Review ..." should be in the subject). Please state clearly whether you think this library should be accepted as a Boost library. Other questions you may want to consider: 1. What is your evaluation of the design? 2. What is your evaluation of the implementation? 3. What is your evaluation of the documentation? 4. What is your evaluation of the potential usefulness of the library? 5. Did you try to use the library? With what compiler? Did you have any problems? 6. How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? 7. Are you knowledgeable about the problem domain? Thanks in advance to all who participate in the review discussion -- I'm looking forward to it! The review manager. --Lorenzo

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Formal review request: TypeIndex library
by Antony Polukhin 05 Aug '12

05 Aug '12

Hi, I'd like to ask to add Boost.TypeIndex to review queue. Introduction TypeIndex is an extended C++11 type_index library, that * works with disabled RTTI * can store const-volatile-reference info about types (if user requested it) * has all the functionality of std::type_index * has portable across compilers and platforms functionality for getting demangled type names * works across modules/shared libraries * does not require C++11 to work Docs: http://apolukhin.github.com/type_index/index.html Git: https://github.com/apolukhin/type_index Sources (zipped): https://github.com/apolukhin/type_index/zipball/master Git contains `patched` folder with TypeIndex'ed (and untested) versions of some existing boost libraries (Boost.Any, Boost.Graph, Boost.Math, Boost.MSM, Boost.PropertyMap, Boost.PropertyTree). Those libraries now do not require RTTI to compile. More libraries could be added to this list. Previous threads (checking interest): * Is there interest in typeid(TYPE).name() like function that does not require RTTI http://lists.boost.org/Archives/boost/2012/05/193491.php * [boost] Is there interest in copyable type_info that does not require RTTI (was: Is there interest in typeid(TYPE).name() like function that does not require RTTI) http://lists.boost.org/Archives/boost/2012/05/193519.php * [boost] [type_index] C++03 implementation in boost? http://lists.boost.org/Archives/boost/2012/07/194627.php P.S.: Additional thanks to Agustín K-ballo Bergé for pointing out and fixing some bugs. P.P.S.: It would be great to schedule review to the end of September. -- Best regards, Antony Polukhin

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[rational] with optional over/underflow checking
by Dan Searles 04 Aug '12

04 Aug '12

Hello, Would there be any interest in a modified "rational" class template/header that optionally allows for an exception be generated if there is under/overflow during any of the operations? I have been developing such a template, where the new defaulted bool template parameter would generate the class exactly as before to preserve the original stable implementation, and to support unlimited-precision integer where over/underflow would not be possible. Setting the new template parameter to true, however would generate code that adds the over/underflow checking. I have also generated new test driver code (BTW test code referenced by the documentation does not appear to exist, or at least the link is broken). rational.hpp has been around and stable for quite some time, so there may be a desire to keep it unchanged, but its original function (and indeed its original source code) can be maintained through the template system. If such a class were to be included in boost, what would be the best submission method?

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Announce: Boost 1.50 installer for 32-bit Windows now available
by John Wiegley 01 Aug '12

01 Aug '12

With apologies to the community for not finding the time to release Windows installers for 1.48 and 1.49, we now have an installer for 1.50 available for immediate download: http://www.boostpro.com/download The version installs 32-bit libraries and/or DLLs for the following compilers: Visual C++ 8.0 (Visual Studio 2005) Visual C++ 9.0 (Visual Studio 2008) Visual C++ 10.0 (Visual Studio 2010) We are dropping support for Visual C++ 7.1 as of this time, unless someone wishes to contract us to bring it back. Also, although I have prepared a 64-bit installer, I have not yet found a solution for integrating it with the existing installer. If anyone with NSIS scripting experience would be willing to assist me, we'd be happy to provide a free installer which installs both 32-bit and 64-bit Boost libraries for applicable Windows platforms. Enjoy! -- John Wiegley BoostPro Computing Software Development Training http://www.boostpro.com Clang/LLVM/EDG Compilers C++ Boost

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[type_erasure] Review ends today July 27, 2012
by Lorenzo Caminiti 01 Aug '12

01 Aug '12

Hello all, On Mon, Jul 23, 2012 at 9:09 AM, Lorenzo Caminiti <lorcaminiti(a)gmail.com> wrote: > On Wed, Jul 18, 2012 at 1:13 AM, Lorenzo Caminiti <lorcaminiti(a)gmail.com> wrote: >> *** The review of Steven Watanabe's proposed Boost.TypeErasure library >> begins on July 18, 2012 and ends on July 27, 2012. *** > > *** Boost.TypeErasure review ends in 5 days. Please submit your reviews :D *** *** Boost.TypeErasure review ends today July 27, 2012. If you are planning to submit a review, please do so as soon as possible. *** Thank you to everyone who has commented on the library and submitted a review so far! The review manager, --Lorenzo P.S. I am considering extending the review until end of day Sunday July 29, 2012... I will keep you posted. > There have been interesting discussions on the library on the ML but I > have not received any official review yet :( Especially if you are a > user of Boost Any, Function, and Any Iterator, you definitely want to > take a look at Type Erasure as it generalizes solutions provided by > those other libraries. > > Thank you. > > The review manager. > --Lorenzo > >> THE LIBRARY >> >> C++ provides runtime polymorphism through virtual functions. They are >> a very useful feature, but they do have some limitations. >> * They are intrusive. In generic programming, we can design an >> interface which allows third-party types to be adapted to it. >> * They require dynamic memory management. Of course, most of the >> problems can be avoided by using an appropriate smart pointer type. >> Even so, it still acts like a pointer rather than a value. >> * Virtual functions' ability to apply multiple independent concepts to >> a single object is limited. >> The Boost.TypeErasure library solves these problems allowing us to >> mirror static generic programming at runtime. >> >> Library source: >> http://svn.boost.org/svn/boost/sandbox/type_erasure/ >> >> Pre-built documentation: >> http://steven_watanabe.users.sourceforge.net/type_erasure/libs/type_erasure/ >> >> You can also download archives with pre-built documentation from: >> http://sourceforge.net/projects/steven-watanabe.u/files/ >> >> YOUR REVIEW >> >> Please submit a review to the mailing-list by replying to this email >> ("[boost] [type_erasure] Review ..." should be in the subject). >> >> Please state clearly whether you think this library should be accepted >> as a Boost library. >> >> Other questions you may want to consider: >> 1. What is your evaluation of the design? >> 2. What is your evaluation of the implementation? >> 3. What is your evaluation of the documentation? >> 4. What is your evaluation of the potential usefulness of the library? >> 5. Did you try to use the library? With what compiler? Did you have >> any problems? >> 6. How much effort did you put into your evaluation? A glance? A >> quick reading? In-depth study? >> 7. Are you knowledgeable about the problem domain? >> >> Thanks in advance to all who participate in the review discussion -- >> I'm looking forward to it!

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Review Request: Endian
by David Stone 01 Aug '12

01 Aug '12

A few months back I posted a proposal for an endian conversion library: http://lists.boost.org/Archives/boost/2012/04/191931.php I believe my library is now in a finished state, and I would like to have it considered for inclusion into Boost. A zip file containing everything can be found here: https://bitbucket.org/davidstone/endian/get/tip.zip or you can just browse the repository here: https://bitbucket.org/davidstone/endian/ The only file that users need to be concerned with is endian.hpp. endian.cpp contains performance + correctness tests, and example.cpp is a very short example program on how to use the library that opens up a file, reads in a number that was written in big-endian format, and prints it to the user's screen in host format. There is no special compiling / linking instructions (people who wish to test the program can simply compile endian.cpp). Included is a SCons script that allows easy compilation with gcc or clang with many warnings + optimizations turned on. My programs all compile cleanly at very high warning levels in these compilers because I know many users compile their own projects at such a setting, and I don't want a library file causing noise. I included the documentation in index.html, but I'm not quite sure on how to correctly format things.

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My take on an allocate_shared_array and make_shared_array implementation
by Glen Fernandes 31 Jul '12

31 Jul '12

Hi all, I've desired an allocate_shared_array for a while (and, looking at some existing threads about the topic, it seems others have also). Recently, while working with a code base that accepted both shared_ptr<T> and shared_array<T> for a sequence of T elements, I decided to write both (for shared_ptr<T> since shared_array<T> does not support allocators). The code for both my make_array<T> and allocate_array<T> initial implementation can be found at: https://github.com/glenfe/glenfern/tree/master/glenfern I was wondering if there is any desire for these (after necessary tweaking, refinement, and testing) to become part of Boost. I'm not certain how useful they are in their current form for people using shared_array<T> that can't switch to shared_ptr<T>. Is there any desire to update shared_array<T> so that it supports custom allocators? In that event, my implementation can then easily be applied to shared_array<T> as well. Alternatively, are there any plans to provide a separate smart pointer type for an array with allocator support? Cheers, Glen

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[block_ptr] Update
by Phil Bouchard 31 Jul '12

31 Jul '12

Hi, It's been more than a year since a completed the block_ptr and it seems as if more recent library are being reviewed first. This would suggest the FIFO of the schedule is not followed. I was just wondering since at the same time the reviewing of block_ptr is cost / beneficial. Regards, -Phil Author of: http://www.fornux.com/ http://www.finitetheory.com/

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Fwd: deep-thought reboot
by DongInn Kim 31 Jul '12

31 Jul '12

Dear all, Can we reboot our NFS server sometime tomorrow? If nobody objects this reboot, I will go ahead to reboot deep-thought at 9am (E.T.) on July 31st, 2012. Date: Tuesday, July 31 2012 Time: - 6:00am-6:10am Pacific US time - 7:00am-7:10am Mountain US time - 8:00am-8:10am Central US time - 9:00am-9:10am Eastern US time - 1:00pm-1:10pm GMT The following services would not be available during the reboot. - NFS $HOME - web sites (e.g., www.open-mpi.org, svn.mpi-forum.org, www.osl.iu.edu/publications, ...) Please let me know if you have any issues or question about the outage. Regards, -- - DongInn --------------------------- CREST System administrator dikim(a)cs.indiana.edu Indiana University Bloomington, IN Begin forwarded message: > From: Rob Henderson <robh(a)indiana.edu> > Subject: deep-thought reboot > Date: July 30, 2012 8:36:41 AM EDT > To: DongInn Kim <dikim(a)osl.iu.edu> > > DongInn, we need to reboot deep-thought in order to get updated raid controller firmware in place and boot to the new kernel. This should be very quick with only a few minutes of downtime. Would there be a good time for us to do this? > > Thanks, > > --Rob

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[type_erasure] Performance
by Julien Nitard 31 Jul '12

31 Jul '12

Hi all, I took time to write a simple benchmark for boost::any. Please find the code attached. It requires C++11. I could only test with g++ because clang 3.0/Ubuntu segfaults on the code. I'd be more than happy to get feedback on whether the tests are relevant. I think the compiler can't impact the result by optimizing away the payloads because there's the virtual call barrier preventing it from doing so. The results are quite good for a library that is not optimized yet. Here are some typical results on my machine (though results may vary slightly on each run): Times are in seconds for 100 million iterations, using -O3 -std=c++0x and no other special flags. * Classic inheritance replacement: Inherited: 0.261134 Erased: 0.260092 Erased + ctor: 0.343596 Erased + ctor 3 concepts: 0.295584 * boost::function replacement: boost::bind: 0.260356 boost::function: 0.469181 std::function: 0.515477 te::any + boost::bind: 0.494241 te::any + lambda: 0.379945 Basically that means that TypeErasure has a cost that's zero or at worse neglectible when compared to normal inheritance. It probably means that those simple use cases can't be optimized since the theoretical performance is achieved. If you create the any object each time, then there's something like a 30% loss. That's against an empty virtual function which means that for non trivial payloads the cost is still low. Good job ! The only thing I can't explain is why creating an any with 3 concepts in an mpl::vector is faster than a single primitive concepts. Any ideas ? Nice as well is that callable<> matches or bests boost::function in the simple cases I have tested (likely to be common thanks to C++ lambdas). Actually, I guess that the results would be even better in "normal" circumstances because the way I wrote the test any has 2 virtual call to perform. I guess that in that case again, optimization is not required before acceptance and release. Regards, Julien

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[multiprecision] Huge testcase datafile in commit r79802
by Lars Viklund 31 Jul '12

31 Jul '12

Hi list. My boost-commit@ mbox made my mail agent go into a nice crawl today when displaying the commit details for r79802. It turns out that it's about 6.3 MiB large, most of which is a massive 100k line test case in sandbox/big_number/libs/multiprecision/performance/delaunay_data.txt Will this behemoth file end up in the real repository in case of library acceptance, and even worse, will it end up in the deployed tarballs? Are there any guidelines on keeping tests neat, or possibly generating performance test data if it's excessively huge? While in the discussion, has there been any thoughts of separating documentation from the tree, and/or having codegen of the source files that are clearly generated (vector200.hpp, etc.) in the build tree? It's very straining on disk space to have multiple Boost trees lying around, particularly if you're working in some kind of homedir environment. Combating-bloat'ly-yours, -- Lars Viklund | zao(a)acc.umu.se

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[type_erasure]suggest tuple doc contain requires clause specifying T... are unique
by Larry Evans 31 Jul '12

31 Jul '12

http://steven_watanabe.users.sourceforge.net/type_erasure/libs/type_erasure… Specifies that the T... are placeholders; however, it doesn't specify that they be unique; hence, tuple<concept,_a,_a> x(int(0),std::vector<int>(0)); would satisfy the current description but wouldn't be right. Of course no one would intentionally do that; however, if the Tags are calculated in some meta-program, it might happened accidentally. Hence the requires class should also say, "If T... are not unique, no diagnostic occurs", or something similar. The reason I think "no diagnostic occurs" is that I've looked briefly in tuple.hpp, at the: ::boost::type_erasure::cons<Concept, T...> impl; in the class tuple definition and the cons definition, and I don't see any check for duplicates. -regards, Larry

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[preprocessor metaprogramming] tools
by Nathan Ridge 31 Jul '12

31 Jul '12

Hello, I've noticed preprocessor metaprogramming has become more popular of late, both as a means to provide a cleaner alternative interface to a library (e.g. the DEFINE and ADAPT macros in Boost.Fusion or the proposed macro wrappers for Boost.TypeErasure) and as a means to emulate new language features (e.g. Boost.LocalFunction, Boost.Generic, and Boost.Contract). Sadly, IDE support for writing macro metaprograms is fairly poor in comparison to IDE support for writing regular C++ code. I wanted to share with you something I've found very useful for tracing/debugging macro metaprograms: the Eclipse CDT IDE has a "macro stepper" that allows you to step through the expansion of a macro step-by-step from the initial invocation to the final expansion. (This feature can be accessed by using the "Explore Macro Expansion" context menu item on a macro invocation.) I would be curious to hear what tools you have found useful for writing or debugging macro metaprograms. Regards, Nate

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Re: [boost] BlueGo Beta 0.0.1
by Julian Amann 30 Jul '12

30 Jul '12

> How can I get the sources? the sources can be found at https://bitbucket.org/Vertexwahn/bluego Julian

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[date_time] Who is in charge?
by Philippe Vaucher 30 Jul '12

30 Jul '12

According to the tracker, it looks like the last ticket with activity is https://svn.boost.org/trac/boost/ticket/5257 which is 16 months ago. Also, according to the mailing list I see a lot of discussion/patches dieing out of inactivity ("[boost] [date_time] warning removal", "[boost] [Date Time] bug in documentation example (Localization Demonstration)"). I'm not here to point fingers, we all have busy times where we just cannot handle open-source responsabilities anymore, but maybe this lib should be switched to "no active maintainers" to avoid any confusion? Also, and probably I should have begin with this, is there a page that lists who is the maintainer of what lib beside the Trac? I couldn't find any, but I didn't look very hard either. Philippe

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[type_erasure]any(U,static_binding) stores wrong type
by Larry Evans 30 Jul '12

30 Jul '12

When the attached is run, it produces output: ./static_binding.exe std::is_copy_constructible<ph_erasee_type>=0 53:ph_ctor_arg<boost::type_erasure::_a>::CTOR.default:my_instance=0 creating a_fst from a_ctor_arg 64:ph_ctor_arg<boost::type_erasure::_a>::CTOR.copy:my_instance=1:(void*)this=0x66ab50 :*fst_cast=ph_erasee<boost::type_erasure::_a>.my_instance=0:(void*)fst_cast=0x66ab50 dynamic_cast<ph_ctor_arg_type*>(value_base_ptr)=0x66ab50 dynamic_cast<ph_erasee_type*>(value_base_ptr)=0 Indicating that a ph_ctor_arg_type is being stored in a_fst instead of the expected ph_erasee_type. -regards, Larry

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