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[Fit] review - ends next 13th Mars
by Vicente J. Botet Escriba 08 Mar '16

08 Mar '16

Hi, we are on the middle of the Fit review stated on 2 Mars and that ends 13th Mars. We have not received a lot of comments, only 4 or 5 people have commented and only a formal review (reject now). I understand that the documentation needs a lot of improvements, nevertheless, this review is the occasion to give as much feedback as possible. If you want to improve this library, please take the time to do a review and share your point of view. Best, Vicente

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Re: [Boost-users] [boost] [Fit] formal review starts today
by Paul Fultz II 07 Mar '16

07 Mar '16

On Sunday, March 6, 2016 at 9:42:19 PM UTC-6, Edward Diener wrote: > > On 3/3/2016 6:43 AM, Vicente J. Botet Escriba wrote: > > Dear Boost community, sorry for the late anounce > > > > The formal review of Paul Fultz II's Fit library starts today, 2nd March > > and ends on 13th March. > > > > Fit is a header-only C++11/C++14 library that provides utilities for > > functions and function objects. > > These are some comments/queries about the Fit documentation. > > Introduction > > The introduction says that Fit "provides utilities for functions and > function objects." But it seems as if Fit works only with lambda > functions and function objects. Fit works with any generalized Callable: http://en.cppreference.com/w/cpp/concept/Callable > The term 'function' normally encompasses > a much larger definition in C++ which includes global functions, static > functions, member functions, and lambda functions. Which is what Callable encompasses, but I used "function" since more people are familiar with that than Callable. > Fit needs to be more > precise in what it says it works with. It repeatedly refers to function > objects and lambda functions as 'functions'. I think this vagueness of > terminality is really confusing in the documentation. > Perhaps, I should refer to the Callable concept early on then. > > Quick Start:Function Objects > > "We can make it behave like a regular function if we construct the class > as a global variable." > > What about a non-global > > sum_f sum = sum_f(); > > makes 'sum' not behave like a regular function other than the fact that > the variable 'sum' may eventually go out of scope ? > In C++, a regular function is always global, there is no such thing as local function(sans gcc extensions). > > Quick Start:Lambdas > > Why do we need both BOOST_FIT_STATIC_LAMBDA and > BOOST_FIT_STATIC_LAMBDA_FUNCTION ? I would seem that > BOOST_FIT_STATIC_LAMBDA_FUNCTION would be adequate and > BOOST_FIT_STATIC_LAMBDA is just redundant, mimicking lambda syntax to no > purpose. > BOOST_FIT_STATIC_LAMBDA_FUNCTION and BOOST_FIT_STATIC_FUNCTION both define a function at global scope, and can only be used at global scope, whereas BOOST_FIT_STATIC_LAMBDA can be used to constexpr initialize local variables as well. In fact, BOOST_FIT_LIFT uses this since it is not always clear what context the user might call BOOST_FIT_LIFT. > > Quick Start:Overloading > > The overloading adaptors show two or more lambda functions. Can they > also work with function objects ? Or a mix of lambda functions and > function objects ? In fact all the reamining Quick Start topics show > examples with lambda functions. Do they also work with function objects ? > Yes it can be used with function objects. I probably should show an example of that as well. I used the lambdas because of the terseness of them. > > Quick Start:Variadic > > I do not understand what 'We can also make this print function varidiac, > so it prints every argument passed into it.' means ? > I'll try to explain that better, but basically it will print each argument, so: print("hello", 5); // Will print "hello" and 5 > > I do not think the Quick Start explains very much since it is dealing > with adaptors of which we know almost nothing and the explanation for > these adaptors and what they actually do is very terse. Probably can expand the explanation of adaptors a little more. > I realize that > is why it is called a 'Quick Start' is because it is just giving the > end-user a quick review of the sort of functionality that the library > entails, but I would much rather see a good Overview first before I look > at anything else in the documentation. > > More Examples > > The more examples section looks at useful cases for the library. Since I > haven't had an overview for the library yet it is disappointing that > this section comes before I really understand how the library is > organized with at least general functionality. I am now given a series > of some highly complicated library syntax without the least idea of why > any of this syntax should be as it is, what it means, or how it works. > That doesn't convince me to use the library at all. It just convinces me > that the library has some showy functionality which does clever things > for particular use cases which the library author wants to convince me I > am going to encounter in my own programming. > Probably more explanation about each of the components used to build the example will be helpful. > > Overview > > The overview section consists of explaining what a function adaptor, > static function adaptor, and decorator are. It also give me some notes > about the syntax of the documentation. I would call this section > 'Definitions' and "Documentation Syntax'. One thing it is not is an > overview of the Fit library as far as I can understand what an overview > is. I also note that following large scale sections deal in Adaptors, > Decorators, Functions, and Utilities. Since 'Functions' and 'Utilities' > are not "defined" in this Overview I am left to wonder if 'Functions' > and 'Utilities' just mean anything in the library which is not an > adaptor or a decorator, and what distinguishes a function from a utility. > This is a good point, the current overview should be called "Definitions". > > In the 'Signatures' section of the Overview I read: > > "All the functions are global function objects except where an explicit > template parameter is required." I honestly don't know what this is > supposed to mean. Does this refer to when function objects are referred > to as parameters to the adaptors, functions, and utilities of the library > ? > I don't understand what you are asking. It means that the function is written like this in the documentation: template<class IntegralConstant> constexpr auto if_(IntegralConstant); But its actually a function object like this in the code: struct if_f { template<class IntegralConstant> constexpr auto operator()(IntegralConstant) const; }; const constexpr if_f if_ = {}; However, `if_c` is written like this in the documentation: template<bool B, class F> constexpr auto if_c(F); It requires the bool `B` template parameter explicity. So in the code it is written as a function and not as a function object. > > The rest of the general About section is fairly straightforward. I still > have no idea of the general functional of the library and why I should > use it. I will only gain an idea of what the library does by reading the > specifics of each adaptor, decorator, function, and utility. This seems > to be the gist of the documentation to me. If I want to understand what > the library does for me in working with function objects and lambda > functions I have to read the specific documentation of each entity in > the library and then go back to the Quick Start and More Examples > sections to further understand how some of these entities are used. > > I think the library documentation would have been much better if there > were a discussion of what the adaptors, decorators, functions, and > utilities of the library were meant to do to enhance user programming > rather than give examples here and there of usage and then leave it up > to the end-user to figure out what, why, and how these entities are to > be used. Quite frankly I don't have a use for a library that does not > attempt to present itself as offering functionality that would be useful > for me in the domain in which the library operates. if I have little or > no idea of that domain I see no reason to think of using a library. > > Since Boost has a number of other libraries dealing with function > objects, most notable the Boost Phoenix library, which is a sort of > successor to the Boost Lambda library, I would think it would be > advantage to the library author to stress functionality in the Fit > library which goes beyond, improves on, or is different from the > functionality in Boost Phoenix, in order to 'sell' end-users on the use > of the Fit library in their code. I do realize that the Fit library > deals with C++11/C++14 idioms, which means that it may be difficult for > many end-users to understand, but I don't think it presents its > documentation in such a way that makes its functionality easier to > understand and I think it should do so. This does not mean that I will > vote right now for Fit to be accepted or not accepted as a Boost > library. I have to look much more carefully at the individual > functionality of the adaptors, decorators, functions, and utilities of > the library to understand what it actually does, before I can vote one > way or another. But I hope my comments and questions about the > documentation to the library will aid the library author in improving > the documentation for end users like me, who are very interested in > library enhancements to function object/lambda function functionality, > but who find the documentation difficult and limiting in certain ways. > Thanks for your feedback, and it will be very helpful in improving the documentation.

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Re: [Boost-users] [boost] [Fit] formal review - should we propose some parts to Boost.Config/Boost.Core
by Vicente J. Botet Escriba 07 Mar '16

07 Mar '16

Le 06/03/2016 09:59, Andrey Semashev a écrit : > On 2016-03-06 05:21, Vicente J. Botet Escriba wrote: >> >> Others could be considered also as function.hpp, lambda.hpp and >> lift.hpp, as the macros are there to workaround some missing language >> features, but those are much more specialized (Boost.Core?) > > I don't think Boost.Core is the right place for them as this library > is for small generally useful components used by many libraries. The > components you pointed out seem too specialized to me, and Boost.Fit > looks like the right place for them. > |Andrey, I was thinking in Boost.Core as these are language-like emulation features, like e.g. addressof, enable_if, explicit_operator_bool, ignorunused, no_exception_support, noncopyanble, scoped_enum, typeinfo. IIUC, BOOST_FIT_STATIC_FUNCTION try to fix a standard Core issue (pending issue 2104 in CWG) identified by Eric Nibler, with the a solution based on proposal's Eric (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/n4381.html) The library has also a macro BOOST_FIT_DECLARE_STATIC_VAR to do it for any data variable. I would like something that solves this problem in Boost. BOOST_FIT_STATIC_LAMBDA try to covers the C++17 feature constexpr lambdas. I suspect that Boost.Hana should have something like that. Louis, could you tell us how do you manage with these issues? IMO, The fiw of those issues is independent from a functional utilities library, even if Fit can not work without them.|| This is way I believe that it should be extracted and Boost.Core seems the good place to me. Best, Vicente |

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Visual Studio C++ and Boost Multiprecision float128
by Michel Lamoureux 06 Mar '16

06 Mar '16

Hi, I use « Visual Studio Express 2013 for Desktop » to do my C++ programming. When I come tu use Boost Multiprecision header « float128.hpp », I get the following message : Fatal error C1189 : #error : « Sorry compiler is neither GCC, not Intel, don’t know how to configure this header. » However, when I use Boost Multiprecision header « cpp_dec_float », it works well but much slowly. I guess « float128.hpp » is faster : Am I right? Is it possible to fix « float128.hpp » to suit C++ from Visual Studio? Thank you for your answer. Michel Lamoureux Envoyé par Courrier<https://go.microsoft.com/fwlink/?LinkId=550986> pour Windows 10

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[Fit] review - github issuess
by Vicente J. Botet Escriba 06 Mar '16

06 Mar '16

Hi, we have started to create some issues in https://github.com/pfultz2/Fit/issues, and sometimes there are some interesting discussion. I will try to add post on the MLs the issues that are conflicting so that other are aware of the discussion. Anyway, if you are curious you can always take a look at and participate also. If you want to receive the updates I believe that you just need to click on watch (top right). Best, Vicente

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Re: [Boost-users] [boost] [Fit] formal review - should we propose some parts to Boost.Config/Boost.Core
by Glen Fernandes 06 Mar '16

06 Mar '16

On Sat, Mar 5, 2016 at 9:21 PM, Vicente J. Botet Escriba wrote: > Others could be considered also as function.hpp, lambda.hpp and lift.hpp, as > the macros are there to workaround some missing language features, but those > are much more specialized (Boost.Core?) > Boost.Core is where we move code from existing Boost libraries that enables breaking cyclic dependencies between different Boost libraries. I'm not so sure new libraries will need to (or want to) put code there. Glen

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Boost.Spirit Karma: debug() alters result
by Matwey V. Kornilov 05 Mar '16

05 Mar '16

Hello, I am using boost 1.58 and I see the following. template <class Iterator> struct test_generator: karma::grammar<Iterator, std::string()> { test_generator(): test_generator::base_type(start) { using karma::ascii::string; using boost::spirit::ascii::char_; using karma::lit; using karma::buffer; using karma::debug; value2 = +(~char_(' ')); value1 = value2; value = lit('=') << value1; start = buffer[-value]; } karma::rule<Iterator, std::string()> start; karma::rule<Iterator, std::string()> value; karma::rule<Iterator, std::string()> value1; karma::rule<Iterator, std::string()> value2; }; template <class Iterator> struct test_generator2: karma::grammar<Iterator, std::string()> { test_generator2(): test_generator2::base_type(start) { using karma::ascii::string; using boost::spirit::ascii::char_; using karma::lit; using karma::buffer; using karma::debug; value2 = +(~char_(' ')); value1 = value2; value = lit('=') << value1; debug(value); start = buffer[-value]; } karma::rule<Iterator, std::string()> start; karma::rule<Iterator, std::string()> value; karma::rule<Iterator, std::string()> value1; karma::rule<Iterator, std::string()> value2; }; template<class It> bool do_generate(It it, const std::string& x) { test_generator<It> g; return karma::generate(it, g, x); } template<class It> bool do_generate2(It it, const std::string& x) { test_generator2<It> g; return karma::generate(it, g, x); } //... std::string x2,x3; do_generate(std::back_inserter(x2), std::string("")); do_generate2(std::back_inserter(x3), std::string("")); std::cerr << "|" << x2 << "|" << std::endl; std::cerr << "|" << x3 << "|" << std::endl; //... The code prints: <unnamed-rule> <try> <attributes>[[]]</attributes> </try> <fail/> </unnamed-rule> |=| || I.e. introduction of debug() alters result of the generator. Could you please explain me where I am wrong? I am stuck now.

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[Fit] upcoming formal review for Boost.Fit
by Vicente J. Botet Escriba 05 Mar '16

05 Mar '16

Dear Boost community, The formal review of Paul Fultz II's Fit library starts on Wednesday, 2nd March and ends on 13th March. Fit is a header-only C++11/C++14 library that provides utilities for functions and function objects. Fit is: - Modern: Fit takes advantages of modern C++11/C++14 features. It support both `constexpr` initialization and `constexpr` evaluation of functions. It takes advantage of type deduction, variadic templates, and perfect forwarding to provide a simple and modern interface. - Relevant: Fit provides utilities for functions and does not try to implement a functional language in C++. As such, Fit solves many problems relevant to C++ programmers, including initialization of function objects and lambdas, overloading with ordering, improved return type deduction, and much more. - Lightweight: Fit builds simple lightweight abstraction on top of function objects. It does not require subscribing to an entire framework. Just use the parts you need. Fit is divided into three components: * Function Adaptors and Decorators: These enhance functions with additional capability. * Functions: These return functions that achieve a specific purpose. * Utilities: These are general utilities that are useful when defining or using functions Fit has been tested on gcc 4.6-4.9, clang 3.4-3.7, and Visual Studio 2015. For more information see: Github:https://github.com/pfultz2/Fit/tree/boost Documentation:http://pfultz2.github.io/Fit/doc/html/ Note that, as Fit is a functional library, the semantic of the functions is given in the form of `equations` instead of the classic effects, returns schema. This is because most of the functions have no side effects. E.g. the semantic of the function flip is defined as |assert(flip(f)(x, y, xs...) == f(y, x, xs...));| and the semantic of compose as |assert(compose(f, g)(xs...) == f(g(xs...)));| We await your feedback! Best regards, Vicente J. Botet Escriba P.S. Paul, now it is time to freeze the version that will be reviewed. I suggest you to create a branch on which you could fix the review issues.

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[Preprocessor] MSVC nonstandard macro expansion workaround?
by rleigh＠codelibre.net 04 Mar '16

04 Mar '16

Hi folks, I've been trying to get Boost.Preprocessor to run a nested for loop over two sequences to output nested switch blocks and case statements. This works fine with GCC and clang. Unfortunately it's broken with MSVC. If anyone had any thoughts on what I might need to tweak to enable the code to work with MSVC, I'd be very appreciative. Even if it's as nasty as a big ifdef with an alternative set of macros! This is the test case: -------- #include <boost/preprocessor.hpp> #include <iostream> #define LASERTYPE_VALUES (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER) enum LaserType { BOOST_PP_SEQ_ENUM(LASERTYPE_VALUES) }; #define PP_SEQ_FOR_EACH_R_ID() BOOST_PP_SEQ_FOR_EACH_R #define PP_DEFER(x) x BOOST_PP_EMPTY() #define LT_NESTED(maR, maToplevelType, maNestedType) \ std::cout << "Test nested: first=" << LaserType(maToplevelType) << " second=" << LaserType(maNestedType) << " \n"; #define LT_TOPLEVEL(maR, maUnused, maType) \ std::cout << "Test toplevel: " << LaserType(maType) << " \n"; \ PP_DEFER(PP_SEQ_FOR_EACH_R_ID)()(maR, LT_NESTED, maType, LASERTYPE_VALUES); int main() { BOOST_PP_EXPAND(BOOST_PP_SEQ_FOR_EACH(LT_TOPLEVEL, %%, LASERTYPE_VALUES)); } -------- On MSVC, I get this: > cl /EHsc /I \path\to\boost-1_60 /Fe:test-pp.exe test-pp.cpp Microsoft (R) C/C++ Optimizing Compiler Version 18.00.40629 for x64 Copyright (C) Microsoft Corporation. All rights reserved. test-pp.cpp test-pp.cpp(22) : warning C4003: not enough actual parameters for macro 'BOOST_PP_VARIADIC_ELEM_3' test-pp.cpp(22) : warning C4003: not enough actual parameters for macro 'BOOST_PP_BOOL' test-pp.cpp(22) : warning C4003: not enough actual parameters for macro 'BOOST_PP_BOOL_I' test-pp.cpp(22) : warning C4003: not enough actual parameters for macro 'BOOST_PP_VARIADIC_ELEM_2' test-pp.cpp(22) : warning C4003: not enough actual parameters for macro 'BOOST_PP_DEC' test-pp.cpp(22) : warning C4003: not enough actual parameters for macro 'BOOST_PP_DEC_I' test-pp.cpp(22) : error C2065: 'BOOST_PP_SEQ_FOR_EACH_M' : undeclared identifier test-pp.cpp(22) : error C2065: 'BOOST_PP_TUPLE_EAT_2' : undeclared identifier test-pp.cpp(22) : error C2065: 'LT_NESTED' : undeclared identifier test-pp.cpp(22) : error C2064: term does not evaluate to a function taking 1 arguments test-pp.cpp(22) : error C2146: syntax error : missing ';' before identifier 'BOOST_PP_IIF_BOOST_PP_BOOL_' test-pp.cpp(22) : error C3861: 'BOOST_PP_IIF_BOOST_PP_BOOL_': identifier not found test-pp.cpp(22) : error C2065: 'BOOST_PP_FOR_3' : undeclared identifier test-pp.cpp(22) : error C2065: 'BOOST_PP_TUPLE_EAT_4' : undeclared identifier test-pp.cpp(22) : error C2059: syntax error : ',' test-pp.cpp(22) : error C3861: 'BOOST_PP_EXPAND': identifier not found test-pp.cpp(22) : error C2065: 'BOOST_PP_FOR_4' : undeclared identifier test-pp.cpp(22) : error C2065: 'BOOST_PP_FOR_5' : undeclared identifier test-pp.cpp(22) : error C2065: 'BOOST_PP_FOR_6' : undeclared identifier test-pp.cpp(22) : error C2065: 'BOOST_PP_FOR_7' : undeclared identifier test-pp.cpp(22) : error C2065: 'BOOST_PP_FOR_8' : undeclared identifier test-pp.cpp(22) : error C2065: 'BOOST_PP_FOR_9' : undeclared identifier test-pp.cpp(22) : error C2065: 'BOOST_PP_FOR_10' : undeclared identifier I've spent hours tweaking the testcase to try to make this work, but so far without success. It doesn't help that I don't fully understand what specifically is broken with the MSVC preprocessor, or how to work around whatever is behaving in a non-stanadard way. Many thanks, Roger

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PBGL in shared memory
by Ярослав 04 Mar '16

04 Mar '16

Hi guys, I need to write some graph parallel algorithms and I decided to use boost graph library for this. There are also PBGL. So my question is, is PBGL works great in shared memory environment. My algorithms will be used in a competition, so I know that it will be launched on a single machine, but with quite high number of cores. Is it worth to use sequential BGL with OpenMP or something, PBGL can handle shared memory and prevent overhead from copying data from one process space to another (as I get it is using MPI)?

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