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Fwd: Changes to __PRETTY_FUNCTION__ in clang
by Mikhail Ramalho 05 Feb '18

05 Feb '18

Hi all, I recently send an email to the clang mailing list, to change how clang prints __PRETTY_FUNCTION__ [0], and one person raised a question if it would break boost. Honestly, I don't know boost's code and I could only find a few places where it's used, mainly for diagnostics, but also in CTTI and hanna; that's why I'm sending this email to ask for some help. Does boost relies on the format of these macros? The main idea is to just change how templates are printed, from: X<void>::X() [T = void] to a gcc-like style: X<T>::X() [with T = void] Thank you, [0] http://lists.llvm.org/pipermail/cfe-dev/2018-February/056766.html -- Mikhail Ramalho.

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[gsoc18][boost.intrusive]
by Rishabh Arora 05 Feb '18

05 Feb '18

Hello Boost Community, I have proposed a project as a mentor for Google Summer of Code '18, as a new addition to the Boost.Intrusive library. The details about the project proposal and the competency test can be found here: https://github.com/ boostorg/boost/wiki/Boost-Google-Summer-of-Code-2018 (Project-5). All the interested candidates can contact me and send me their competency test on the following e-mail: rishabharora1997(a)gmail.com Best Regards, Rishabh

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Re: [boost] [CppCMS] What can be contributed to Boost?
by Bjorn Reese 04 Feb '18

04 Feb '18

On 02/02/18 19:30, Artyom Beilis via Boost wrote: > Once I can think of is cppcms::json > > http://cppcms.com/wikipp/en/page/cppcms_1x_json > http://cppcms.com/cppcms_ref/latest/classcppcms_1_1json_1_1value.html > > Also it should be updated to C++11 and probably do some small features > updates. it is one of the fastest JSON parsers around (and yes it is > way faster and convenient than one in property tree) > > What do you think? If the Boost community wants a JSON library, then I would like to suggest another, more versatile ibrary: https://github.com/breese/trial.protocol Documentation can be found here: http://breese.github.io/trial/protocol/ This library consists of two (well, three) parts: 1. A dynamic variable which is a variant type that can contain fundamental types, arrays, and associative arrays. This can be used as a parse tree for JSON and similar binary formats like MsgPack, UBJSON, BinToken, and CBOR. But it can also be used as a data container for, say, configuration data. The dynamic variable has iterators so it works with std algorithms. It also comes with a visitor. 2. A JSON parser/generator framework. This contains an incremental pull parser (json::reader) as the basic building-block. The incremental parser is used by a Boost.Serialization archive to enable serialization directly between JSON and C++ data structures. The incremental parser is also used by a tree parser that converts JSON into the before-mentioned dynamic variable. 3. A BinToken parser/generator framework. Like the JSON framework, but for the binary BinToken format. Currently undocumented.

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[CppCMS] What can be contributed to Boost?
by Artyom Beilis 02 Feb '18

02 Feb '18

Hello Dear Boost Developers, Recently I had released CppCMS - C++ Web Framework 1.2 under MIT license instead of LGPLv3 See: http://cppcms.com Since CppCMS project had already contributed some of its parts for Boost: Boost.Locale - in Boost for long time Boost.Nowide (passed review still need some my time to integrate to release) I wanted to renew the discussions of what parts may interest the community Boost outside CppCMS. Some samples I thought of: -------------------------------------------- Once I can think of is cppcms::json http://cppcms.com/wikipp/en/page/cppcms_1x_json http://cppcms.com/cppcms_ref/latest/classcppcms_1_1json_1_1value.html Also it should be updated to C++11 and probably do some small features updates. it is one of the fastest JSON parsers around (and yes it is way faster and convenient than one in property tree) What do you think? -------------------------------------- Another one that was already discussed once is CppDB: http://cppcms.com/sql/cppdb/ It also needs C++11 updates in general and is already under dual Boost/MIT License. It was discussed before but nothing moved further. ---------------------------------- Some smart pointers I find very useful especially for Pimpl implementation: hold_ptr -> similar to scope ptr but object constness is same as the pointer copy_ptr-> copies underlying object upon copy (very useful for pimpl) clone_ptr->clones objects. Regards, Artyom Beilis

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[serialization] uuid test_serialization ubsan error
by James E. King, III 01 Feb '18

01 Feb '18

I'm getting a ubsan test error in uuid/test/test_serialization - is the code in that test using archive the right way? testing.capture-output ../../../bin.v2/libs/uuid/test/test_serialization.test/gcc-7/debug/link-static/threadapi-pthread/test_serialization.run ====== BEGIN OUTPUT ====== ../../../boost/archive/detail/interface_oarchive.hpp:47:16: runtime error: downcast of address 0x7ffca0c6fe30 which does not point to an object of type 'text_oarchive' 0x7ffca0c6fe30: note: object is of type 'boost::archive::text_oarchive_impl<boost::archive::text_oarchive>' 00 00 00 00 e0 2f 78 8f 48 56 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ^~~~~~~~~~~~~~~~~~~~~~~ vptr for 'boost::archive::text_oarchive_impl<boost::archive::text_oarchive>' EXIT STATUS: 1 ====== END OUTPUT ====== Thanks, Jim

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Re: [boost] [review] Review of Outcome v2 (Fri-19-Jan to Sun-28-Jan, 2018)
by Andrzej Krzemienski 01 Feb '18

01 Feb '18

2018-02-01 19:13 GMT+01:00 Emil Dotchevski <emildotchevski(a)gmail.com>: > On Thu, Feb 1, 2018 at 2:51 AM, Andrzej Krzemienski <akrzemi1(a)gmail.com> > wrote: > >> Boost.Outcome solves the problem decently: you get a compiler error or a >> compiler warning >> > > Do you? What if you have: > > result<void> foo(); > > void bar() > { > foo(); > } > > What compile error will that generate? > "ignoring returned value of type 'outcome_v2_f1696316::result<void>', declared with attribute nodiscard [-Werror=unused-result]" online example: https://wandbox.org/permlink/5vICxckvVG6QO0n1 > Now, in Boost.Noexcept, if the programmer forgets to test for the failure >> (with `try_`), the subsequent function is still executed with the default >> value of type `T` returned from the funciton that failed. Because in >> Boost.Noexcept when function fails it returns a default-constructed `T`. >> > > The idea in Noexcept is that since the function _must_ return something if > there is an error, it returns throw_return<T>() but that is not automatic; > the user still has to say e.g. return throw_(error()). > I understand the constraints you are under. I also acknowledge that this is the best one can do. Nonetheless, I still see the limitation of the solution. If a third party function is returning a type representing a resource, and this type does not provide a default constructor, there is no way to "throw_". You cannot even customize `throw_return<T>()` because what value would you return? You are reporting failure because you cannot acquire the resource. And because it is a third-party interface, you cannot adapt the type. So, in the end, there will be functions where you cannot apply Boost.Noexcept. > > >> And when you check it systematically it is all ok, but then you forget >> (and this is a tedious task), you violate the contracts. No compile-time >> check, no run-time check. >> > > In Noexcept there _is_ run-time check: if noexcept_::has_current_error() > is true at the time a thread terminates, it invokes std::terminate(). Not > ideal, and won't take action if the thread never terminates -- and it may > never terminate because, like in Outcome, if the caller doesn't check at > every function call, the program keeps going. > I was imprecise. you do have a run-time check, but it comes too late: it does not prevent functions to be called with failed preconditions. > > >> I consider this a serious issue. >> > > It is, programmers forget to check for errors all the time. > And Boost.Outcome helps detect these situations at compile-time (of course, at the expense of controlling the return type). > >> And taking into consideration the advantages of Boost.Noexcept you >> mention, I can only conclude that Boost.Noexcept is superior to >> Boost.Outcome in one aspect but inferior in another. >> > > The two libraries solve different problems. > Indeed. > Outcome helps you avoiding exception handling, so it assumes you can > freely use result<T,E> throughout your interfaces. > Well, it can help you avoid exceptions. But it also helps you deal with the lack of exception handling. As you say, the trade-off is that you use `result` in return type. > Noexcept helps you deal with a lack of exception handling, so it assumes > that at least some of the interfaces are beyond your control, and doesn't > impose a return type. > Yes, here the trade-off is, no altering of the return type, but unsafe consequences when you forget to check for "thrown" exceptions. And there must exist a "spare" value in the returned type. There are benefits to using a special return type (to protect against using > an invalid value), but Noexcept leaves that to the user because return > values don't transport errors, just the T; you could e.g. use > std::optional<T>. > And user may not be able to make this decision because he may not be in control of the return type. Regards, &rzej;

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[GSOC18] Boost.Geometry Project 1 : Similarity between geometries
by sagarvijaygupta 31 Jan '18

31 Jan '18

I am Sagar Gupta, a student of IIT Mandi, pursuing my Bachelors in Computer Science. I want to work on the Project 1 of Similarity between Geometries. I read the source code of geometry and regarding the Frechet distance and its different variations and tried to work with it. Also I tried the competency test. Its my first time for GSOC but I have some good experience in C++ (from different projects and competitive programming). I wish to know where should I send the competency test? I wish to work on this project as it is a great learning experience which I realized while working on the implementation of Frechet Distance between linestrings. Thanks and Regards Sagar Gupta -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Dev-f2600599.html

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International Conference on Information Society (i-Society 2018): Call for Submissions!
by International Conference on Information Society 30 Jan '18

30 Jan '18

Apologies for cross-postings. Please send it to interested colleagues and students. Thanks! Call for Submissions! ********************************************************************************** International Conference on Information Society (i-Society 2018) 15-18 July, 2018 Venue: Ballsbridge Hotel Dublin, Ireland www.i-society.eu ********************************************************************************* The i-Society is a global knowledge-enriched collaborative effort that has its roots from both academia and industry. The conference covers a wide spectrum of topics that relate to information society, which includes technical and non-technical research areas. The mission of i-Society 2018 conference is to provide opportunities for collaboration of professionals and researchers to share existing and generate new knowledge in the field of information society. The conference encapsulates the concept of interdisciplinary science that studies the societal and technological dimensions of knowledge evolution in digital society. The i-Society bridges the gap between academia and industry with regards to research collaboration and awareness of current development in secure information management in the digital society. The topics in i-Society 2018 include but are not confined to the following areas: *New enabling technologies - Internet technologies - Internet of Things (IoT) - Wireless applications - Mobile Applications - Cloud and iCloud - Multimedia Applications - Protocols and Standards - Ubiquitous Computing - Virtual Reality - Human Computer Interaction - Geographic information systems - e-Manufacturing - Electronic Discovery (eDiscovery) - Software Applications - Disruptive Technology *Intelligent data management - Intelligent Agents - Intelligent Systems - Intelligent Organisations - Content Development - Data Mining - Data Management Software - e-Publishing and Digital Libraries - Information Search and Retrieval - Knowledge Management - e-Intelligence - Compliance and Recovery from Data Loss - Knowledge networks - Risk Mitigation - Cost Efficiency - Quality Assurance - Information Management - Support Litigation - Complex Investigations *Secure Technologies - Internet security - Web services and performance - Secure transactions - Cryptography - Payment systems - Secure Protocols - e-Privacy - e-Trust - e-Risk - Cyber Security Investigations and Defence - Cyber law - Forensics - Information assurance - Mobile social networks - Peer-to-peer social networks - Sensor networks and social sensing - Information Security Compliance *e-Learning - Collaborative Learning - Curriculum Content Design and Development - Delivery Systems and Environments - Educational Systems Design - e-Learning Organisational Issues - Evaluation and Assessment - Virtual Learning Environments and Issues - Web-based Learning Communities - e-Learning Tools - e-Education *e-Society - Global Trends - Social Inclusion - Intellectual Property Rights - Social Infonomics - Computer-Mediated Communication - Social and Organisational Aspects - Globalisation and developmental IT - Social Software - Smart City *e-Health - Data Security Issues - e-Health Policy and Practice - e-Healthcare Strategies and Provision - Medical Research Ethics - Patient Privacy and Confidentiality - e-Medicine *e-Governance - Democracy and the Citizen - e-Administration - Policy Issues - Virtual Communities *e-Business - Digital Economies - Knowledge economy - eProcurement - National and International Economies - e-Business Ontologies and Models - Digital Goods and Services - e-Commerce Application Fields - e-Commerce Economics - e-Commerce Services - Electronic Service Delivery - e-Marketing - Gig Economy - Online Auctions and Technologies - Virtual Organisations - Teleworking - Applied e-Business - Electronic Data Interchange (EDI) - Innovative Strategies - Business Intelligence - Information Intelligence - Forensic Accounting *e-Art - Legal Issues - Patents - Enabling technologies and tools *e-Science - Natural sciences in digital society - Biometrics - Bioinformatics - Collaborative research *Industrial developments - Trends in learning - Applied research - Cutting-edge technologies - Industrial Control Systems - Communications Compliance * Research in progress - Ongoing research from undergraduates, graduates/postgraduates and professionals SUBMISSION INSTRUCTIONS: * You can submit your abstract, extended abstract or paper online at http://www.i-society.eu/paper-submission/ or email it to papers(a)i-society.eu * You can submit your speaker's proposal via email at speakers(a)i-society.eu or online at http://www.i-society.eu/format/speakers-participation/ * You can submit your poster via email at posters(a)i-society.eu * You can submit your workshop or tutorial proposal via email at workshop(a)i-society.eu or tutorial(a)i-society.eu * You can submit your panel discussion via email at pandis(a)i-society.eu IMPORTANT DATES: *Abstract Submission Date: February 10, 2018 *Notification of Abstract Acceptance / Rejection: February 17, 2018 *Extended Abstract (Work in Progress) Submission Date: February 20, 2018 *Notification of Extended Abstract Acceptance / Rejection: February 27, 2018 *Research Paper Submission Date: March 01, 2018 *Notification of Research Paper Acceptance / Rejection: March 12, 2018 *Camera Ready Paper Due: May 01, 2018 *Proposal for Workshops / Tutorials: February 25, 2018 *Notification of Workshop/Tutorials Acceptance / Rejection: March 01, 2018 *Poster / Demo Proposal Submission: March 01, 2018 *Notification of Poster / Demo Acceptance: March 12, 2018 *Early Bird Registration Deadline (Authors and Participants): April 15, 2018 *Late Bird Registration Deadline (Authors only): May 15, 2018 *Late Bird Registration Deadline (Participants only): May 30, 2018 *Conference Dates: July 15-18, 2018 For more details, please visit www.i-society.euIf you wish to unsubscribe from our newsletter, click http://r.confinfosoc.org/scyaulavbnjg.html

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Interested in applying to the google summer of code
by Laouen Belloli 30 Jan '18

30 Jan '18

Hi, My name is Laouen Belloli, I'm a Computer Science student at Universidad de Buenos Aires currently doing my final thesis in Discrete Events Simulation, this is my 7th and last year on it. In the past I contributed to the cadmium project. This year, I want to join the google summer of code to contribute to Boost. In particular, I would like to work on the Boost.Real project proposed. Best regards, -- Laouen Mayal Louan Belloli. LIAA - DC - FCEyN - UBA. C.A.B.A. - Buenos Aires - Argentina. https://liaa.dc.uba.ar +54 9 11 38675694

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[atomic] (op)_and_test naming
by Andrey Semashev 30 Jan '18

30 Jan '18

Hi, I would like to ask for the community opinion on the naming of the (op)_and_test functions that appeared in Boost.Atomic 1.66. As you probably know, 1.66 included a few new atomic operations, some of which have the name (op)_and_test (e.g. add_and_test, sub_and_test, etc.) These operations perform the (op) on the atomic value and test if the result is zero, so that instead of this: if (a.fetch_sub(1) - 1 == 0) one could write this: if (a.sub_and_test(1)) Also, the generated code for these operations can potentially be more efficient. Recently I received this request: https://github.com/boostorg/atomic/issues/11 which basically asks to change the result of the functions to the opposite. I can see that the current naming could be confusing, especially given that other operations like bit_test_and_set return the previous bit value (i.e. true if the bit was 1). That would be a breaking change, but the new operations were announced as experimental in the release notes, so if there is consensus that the result should indeed be changed, I'm ready to comply. Another solution is change (op)_and_test naming to something else that is more clear. In that case I could deprecate the (op)_and_test variants and provide the functionality under the new names. I would welcome suggestions for a better naming scheme, if you feel this is the right way. My only ask is that the new names be concise, if possible. Lastly, if you think the current naming is fine or there is another way to resolve the confusion, please comment as well. I would appreciate your opinion in any case. Thanks.

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[review] Outcome v2: Review Period Concluded (Fri-19-Jan through Sun-28-Jan, 2018)
by charleyb123 . 29 Jan '18

29 Jan '18

Hi, Everyone-- The Boost Review Period for the formal review of Niall Douglas' Outcome (v2) library is concluded (having run Fri-19-Jan through Sun-28-Jan, 2018). Reviews were posted from: - Vinícius dos Santos Oliveira (Fri-26-Jan-2018) - Andrzej Krzemienski (Fri-26-Jan-2018) - Bjorn Reese (Sun-28-Jan-2018) - Daniela Engart (Sun-28-Jan-2018) - John P Fletcher (Sun-28-Jan-2018) In addition, online discussions included comments, observations, and critiques from a number of other community participants. It will take some time to review the discussion, make a final determination, and prepare the Review Report. Please: - Contact me (directly or on-list) if I missed identification of your review during the review period; - Contact me (directly or on-list) if you have any concerns; or to raise any salient observations or "final thoughts" Thank you! --charley Boost.Outcome(v2) Review Manager

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[gsoc18] Interested in adding statistics and machine learning functions to Boost.uBLAS and Seeking for mentors
by Kanch 29 Jan '18

29 Jan '18

Dear community: My name is Long Zhang,currently in my third year of college. As subject suggests, I'm interested in adding statistics and machine learning functions to Boost.uBLAS library. I've basic knowledge of statistics (which I have been thought in school) and Machine Learning, I learned Machine Learning by Andrew Ng on Coursera, and I have tried to implement algorithms like PCA,LDA,K-means in Python, therefore, I think it won't be a problem if I have to implements it in C++. BTW, I have use C++ since my Senior High. Except components mentioned in wiki, I think I can also implement algorithms like KNN,Logistic Regression, even SVM during the summer. I also understand the efficiency of these algorithms is what matters, I will try hard to implement it as fast as it can. I know I have do some kind of programming competency test. When should I start? I mean I haven't find a mentor, don't know who should I contact if I finish the test. Can someone mentoring me? We can then talk about the test and code I used written in C++(open source code in C++) to check if I'm qualified to this project. Thank you. Best, Long -- Best regards, *Long Zhang (Kanch) <http://akakanch.com> *＠ Chengdu University of Information Technology 2015 Computer Science Major Mail:kanchisme@gmail.com No.24 Block 1, Xuefu Road, Chengdu, Sichuan, China

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[outcome] Formal review
by Bjorn Reese 29 Jan '18

29 Jan '18

I. DESIGN --------- Boost.Outcome provides a useful alternative / complement to exceptions, and its design is clean. I like naming of functions with wide and narrow contracts. I suggest that result<> is renamed to basic_result<>, which will then be the customizable template class, and result<> then becomes as specialzation (template alias) that does the same as the current default result<>. This makes result<> an uncustomizable companion to std::error_code, which is useful when defining interoperable APIs. One design decision that I disagree with is the choice of sum types rather than product types for internal storage. I would rather have a lower run-time footprint at the expense of increased compile times. II. IMPLEMENTATION ------------------ Looks readable and solid. There may be an overemphasis on constexpr; I would rather have had support for C++11. BOOST_OUTCOME_TRY_UNIQUE_NAME generates identifiers starting with __t but according to the C++ standard [lex.name/3.1] "each identifier that contains a double underscore __ [...] is reserved to the implementation for any use", where implementation means the C++ compiler. III. DOCUMENTATION ------------------ The documentation is well-written, with a tutorial that is easy to understand. The API Reference could be improved though. 1. What are the requirements for ValueOrError? Looking up ValueOrError brings us to convert::value_or_error, which only states that it "matches the ValueOrError concept." The rather convoluted enable_if uses ValueOrError<U> which uses detail::ValueOrError<U> and here the trail disappears. The convert.hpp header file does contain the missing explanations though. 2. What are the requirements for EC and EP? EC and EP are used informally throughout the documentation, but are described in the Custom Payloads tutorial. In the API Reference they are suddenly called S and P instead. Please use a consistent naming throughout the documentation; preferably using more descriptive names, such as OutcomeErrorCode and OutcomeExceptionPtr. It would furthermore be helpful if they were described as concepts outside the tutorial. 3. The descriptions of value_type_if_enabled and error_type_if_enabled are obscure, and it is still not clear to me if they have any relevance for the library user. If they do, then their descriptions should be more clear; if they do not, then they should not be included in the documentation. 4. The documentation of OUTCOME_TRYX contains the full macro implementation which is not really helpful to users. This macro could possibly be expressed in terms of other macros. 5. noexcept('hidden') is used in several places. Does this mean that the noexcept condition is unspecified? If so, then it is more customary to use "unspecified" in italic. IV. MISC -------- I spent 4-5 hours reading the documentation and looking at the code. I did not compile it. V. VERDIC --------- I vote for the conditional acceptance of Boost.Outcome. The conditions are: 1. The documentation should be integratable into the Boost infrastructure. 2. People must be able to submit patches to the Boost version of the library without having to convert those patches to the standalone version.

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Fwd: Fwd: [review] Review of Outcome v2 (Fri-19-Jan to Sun-28-Jan, 2018)
by degski 28 Jan '18

28 Jan '18

---------- Forwarded message ---------- From: degski <degski(a)gmail.com> Date: 28 January 2018 at 17:11 Subject: Re: [boost] Fwd: [review] Review of Outcome v2 (Fri-19-Jan to Sun-28-Jan, 2018) To: Vinícius dos Santos Oliveira <vini.ipsmaker(a)gmail.com> On 28 January 2018 at 16:44, Vinícius dos Santos Oliveira < vini.ipsmaker(a)gmail.com> wrote: > Can you elaborate on your point? If I'm left alone I'll miss your point. > I was mostly just responding to your example (which you asked me to do), and how I would do that, without having to deal with exceptions and/or outcomes. But, the more general point is, which Spirit in this case does very well, is to deal with potential problems at the source, in an explicit (comprehensive) way, without propagation of errors or exceptions. > It's becoming confusing the more you go. > It's probably because I'm rowing against the tide here. degski

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Fwd: [review] Review of Outcome v2 (Fri-19-Jan to Sun-28-Jan, 2018)
by degski 28 Jan '18

28 Jan '18

Accidentally sent privately, forwarded below: ---------- Forwarded message ---------- From: degski <degski(a)gmail.com> Date: 28 January 2018 at 15:46 Subject: Re: [boost] [review] Review of Outcome v2 (Fri-19-Jan to Sun-28-Jan, 2018) To: Vinícius dos Santos Oliveira <vini.ipsmaker(a)gmail.com> On 28 January 2018 at 14:10, Vinícius dos Santos Oliveira < vini.ipsmaker(a)gmail.com> wrote: > 2018-01-28 12:12 GMT-03:00 degski via Boost <boost(a)lists.boost.org>: > >> 1. Use of outcome is more manual and cumbersome, i.e. more error-prone. >> > > What is complex about the following? > <snipped the code> I'd just use boost::cnv::spirit and specify explicitly what happens when conversion didn't work... much shorter, very well optimized (the best) when it does work (the conversion)... > Server side code... > There's more than servers in life. Handling f.e. O-O-M-situations is not gonna help me on my lap-top... a re-think and re-write of my app is in this case in order, though... or a trip to the shop and buy a bigger stick (both the "slow path"). > If the error is exceptional or not, it depends on context, not on the > algorithm (e.g. connection failure on game client code and game server code > and both of them being backed up by the same functions). Boost.Outcome > let's you do just that by converting an error into an exception. > Yeah, that's another discussion, isn't it? errors vs. exceptions. Should exceptions be exceptional, or getting back to your conversion example, should we use exceptions to indicate failure as this is the case in Boost::Lexical_cast? I know the answer I like best, and moved on to Boost.Spirit. degski

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[spirit-x3]What's use case for x3::variant<OnlyOneComponent>?
by Larry Evans 28 Jan '18

28 Jan '18

Since: http://www.boost.org/doc/libs/1_65_0/libs/spirit/doc/html/spirit/qi/quick_r… doesn't mention a unary variant: variant<A> and the comments in: https://github.com/boostorg/spirit/blob/develop/include/boost/spirit/home/q… indicates variant<T> is collapsed to T, why isn't the x3::variant here: https://github.com/boostorg/spirit/blob/develop/include/boost/spirit/home/x… declared as: template <typename L, typename R, typename ...Types> struct variant instead of: template <typename ...Types> struct variant which allows sizeof...(Types)==0 instead of the minimum size of 2? That would disallow the primary and factor using's here: https://stackoverflow.com/questions/43791079/x3-linker-error-with-separate-… which make no sense because, for example, primary_def is *not* an alternative parser. -regards. Larry

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Google Summer of Code with Boost
by David Bellot 28 Jan '18

28 Jan '18

Hi everyone, still a few days before we submit our proposal to Google. Don't loose the chance to become a mentor for Boost. It shines on your CV, it is a great opportunity to work with brilliant students around the world, it makes you an official C++ world-wide expert. So far, we have a nice but little list of proposals here: https://github.com/boostorg/boost/wiki/Boost-Google-Summer-of-Code-2018 It would be good to have a bit more before I go and submit to Google. This will increase our chances to be selected again this year. For Boost it's a great funding worth several thousand of dollars every year. We just don't want to miss it. Best regards, David

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[gsoc18] New Astronomy Library
by Pranam Lashkari 28 Jan '18

28 Jan '18

Boost has developed many libraries which is useful in the field of science. I would like to propose a library for "Astronomy" as a student. I have been an amateur astronomer since last 8 years and being a Computer Engineering student I will be able to develop this library with little mentoring. I have some ideas about what can be integrated into it, which I can propose if the proposal seems promising. If so are there anyone who can help me out with this and mentor me? Thank you, Pranam Lashkari

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[gsoc18] ublas project 3
by Aperjump 28 Jan '18

28 Jan '18

I'm Wei Wang, a CS master student focusing on high-performance computing field. `boost::ublas` project 3 adding GPU computation interests me a lot and I'd like to help add this feature to ublas. I find this project was also on last years' list and I'm curious if anyone did this before or on which stage he/she has finished. I've already read the initial source code of `ublas` in `boost 1.29`(I also read 1.66 API, and found it add one concept `container`, which used to be `bounded_array` and `unbounded_array`). I wrote a passage describing its template parameter deduction relationships. Besides, I wrote a series blogs teaching how to use openCL efficiently with proper data partition and memory usage. This is my first time participating in GSOC, and I'm a bit of confused on following question: 1. Integrating openCL requires preparing for context, command_queue, event and other "environment objects", should they also be included in this lib? 2. Take matrix matrix multiplication A*B for example. The last stage before matrix copy assignment is in `matrix_matrix_prob` class and its evaluation requires loop through all items on both matrix. If I want to add GPU compute features, I need to launch kernel for each computation expression at this step, but it seems to be contradictory to `ublas`'s lazy evaluation rationale. How to reconcile that? 3. What should I implement in the competency matrix class? Just integer matrix or template matrix class?Should I support current `ublas` interface(those typedefs and traits)? Best regards, Wei Wang -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Dev-f2600599.html

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Re: [boost] [review] outcome broken on clang/libstdc++ (Linux) and Apple clang/libc++ and gcc 7.2
by Glen Fernandes 28 Jan '18

28 Jan '18

I wrote a .travis.yml for your boost-outcome submission to run your unit tests against a few compilers: The output is at: https://travis-ci.org/glenfe/ned14.outcome/builds/334222400 I updated it to make sure the clang++-libstdc++ uses a more recent libstdc++. It looks like: - clang++-libc++ fails because of forgetting to #include a header. - GCC 7.2 with -std=c++17 is the one with the Internal Compiler Errors (I didn't investigate further) - clang++5-libstdc++ fails because it cannot find a type in std Is there a reason why you don't have travis and appveyor for boost-outcome? I remember your "Best Practices" document strongly advocating that every Boost library submission should have them. Glen

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Re: [boost] [review] outcome broken on clang/libstdc++ (Linux) and Apple clang/libc++ and gcc 7.2
by Glen Fernandes 27 Jan '18

27 Jan '18

On Sat, Jan 27, 2018 at 4:55 PM, Glen Fernandes wrote: > I just tried boost-outcome unit tests with clang 4.0, 5.0 on Linux > with libstdc++ with -std=c++14 and -std=c++1z which fails with many > errors: > > e.g. [snip] > In file included from > libs/outcome/test/tests/../../include/boost/outcome/detail/result_storage.hpp:34: > libs/outcome/test/tests/../../include/boost/outcome/detail/../success_failure.hpp:54:42: > error: no template named 'conditional_t' in namespace 'std'; did you > mean 'conditional'? > template <class T> using devoid = > std::conditional_t<std::is_void<T>::value, void_type, T>; > ~~~~~^~~~~~~~~~~~~ > conditional > /usr/bin/../lib/gcc/x86_64-linux-gnu/4.8/../../../../include/c++/4.8/type_traits:1780:12: > note: 'conditional' declared here > struct conditional > ^ > > > Then I also tried the boost-outcome unit tests with Apple clang 8.1.0 > with libc++ with -std=c++14 and -std=c++1z which fails with errors > like: > I pasted the wrong error output here; the right error output is: clang-darwin.compile.c++ bin.v2/libs/outcome/test/core-outcome.test/clang-darwin-4.2.1/debug/cxxstd-14-iso/tests/core-outcome.o In file included from libs/outcome/test/tests/core-outcome.cpp:30: In file included from libs/outcome/test/tests/../../include/boost/outcome/outcome.hpp:34: In file included from libs/outcome/test/tests/../../include/boost/outcome/detail/outcome_exception_observers.hpp:34: In file included from libs/outcome/test/tests/../../include/boost/outcome/detail/result_storage.hpp:35: libs/outcome/test/tests/../../include/boost/outcome/detail/value_storage.hpp:181:22: error: no matching constructor for initialization of 'value_type' (aka 'boost::outcome_v2::outcome<int, std::__1::error_code, std::exception_ptr, boost::outcome_v2::policy::error_code_throw_as_system_error<int, std::__1::error_code, std::exception_ptr> >') new(&_value) value_type; // NOLINT ^ libs/outcome/test/tests/../../include/boost/outcome/detail/result_storage.hpp:270:11: note: in instantiation of member function 'boost::outcome_v2::detail::value_storage_nontrivial<boost::outcome_v2::outcome<int, std::__1::error_code, std::exception_ptr, boost::outcome_v2::policy::error_code_throw_as_system_error<int, std::__1::error_code, std::exception_ptr> > >::value_storage_nontrivial' requested here : _state(std::move(o._state)) ^ > Is this also a known issue? Only gcc 6 and gcc 7 with lisbtdc++ on > Linux seem to pass. The other combinations I tried (clang + lisbtdc++ > on Linux, Apple clang + libc++) do not. > I spoke too soon, here gcc 7 does not pass. It ICEs: libs/outcome/test/tests/../../include/boost/outcome/detail/result_value_observers.hpp:45:17: in constexpr expansion of ‘((boost::outcome_v2::detail::result_value_observers<boost::outcome_v2::detail::result_storage<int, std::errc, boost::outcome_v2::policy::error_code_throw_as_system_error<int, std::errc, void> >, int, boost::outcome_v2::policy::error_code_throw_as_system_error<int, std::errc, void> >*)this)->boost::outcome_v2::detail::result_value_observers<boost::outcome_v2::detail::result_storage<int, std::errc, boost::outcome_v2::policy::error_code_throw_as_system_error<int, std::errc, void> >, int, boost::outcome_v2::policy::error_code_throw_as_system_error<int, std::errc, void> >::<anonymous>.boost::outcome_v2::detail::result_storage<int, std::errc, boost::outcome_v2::policy::error_code_throw_as_system_error<int, std::errc, void> >::result_storage<int>(boost::outcome_v2::in_place_type_t<int>(), <anonymous>)’ libs/outcome/test/tests/core-result.cpp:330:41: internal compiler error: in adjust_temp_type, at cp/constexpr.c:1206 constexpr result<int, std::errc> a(5), b(std::errc::invalid_argument); [...] 0x6db788 cxx_eval_constant_expression ../../src/gcc/cp/constexpr.c:4034 Please submit a full bug report, with preprocessed source if appropriate. Please include the complete backtrace with any bug report. See <file:///usr/share/doc/gcc-7/README.Bugs> for instructions. Let me know if you need more context, but it appears boost-outcome is also broken on gcc 7.2. Glen

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Re: [boost] [review] outcome broken on clang with libstdc++ (Linux) and Apple clang with libc++
by Glen Fernandes 27 Jan '18

27 Jan '18

On Sat, Jan 27, 2018 at 3:07 PM, Niall Douglas wrote: > b2 libs/afio/test works fine with VS2017. So it would seem that that ICE > Vinnie encountered is some weird corner case nobody could have > anticipated. As I mentioned, almost all of the development of Outcome > was done on MSVC. It's very well tested on MSVC, and I've never seen > anything like that ICE before. I just tried boost-outcome unit tests with clang 4.0, 5.0 on Linux with libstdc++ with -std=c++14 and -std=c++1z which fails with many errors: e.g. In file included from libs/outcome/test/tests/comparison.cpp:35: In file included from libs/outcome/test/tests/../../include/boost/outcome/outcome.hpp:34: In file included from libs/outcome/test/tests/../../include/boost/outcome/detail/outcome_exception_observers.hpp:34: In file included from libs/outcome/test/tests/../../include/boost/outcome/detail/result_storage.hpp:34: libs/outcome/test/tests/../../include/boost/outcome/detail/../success_failure.hpp:54:42: error: no template named 'conditional_t' in namespace 'std'; did you mean 'conditional'? template <class T> using devoid = std::conditional_t<std::is_void<T>::value, void_type, T>; ~~~~~^~~~~~~~~~~~~ conditional /usr/bin/../lib/gcc/x86_64-linux-gnu/4.8/../../../../include/c++/4.8/type_traits:1780:12: note: 'conditional' declared here struct conditional ^ Then I also tried the boost-outcome unit tests with Apple clang 8.1.0 with libc++ with -std=c++14 and -std=c++1z which fails with errors like: clang-darwin.compile.c++ bin.v2/libs/outcome/test/outcome-int-int-1.test/clang-darwin-4.2.1/debug/cxxstd-14-iso/outcome-int-int-1.o libs/outcome/test/compile-fail/outcome-int-int-1.cpp:12:26: error: no matching constructor for initialization of 'outcome<int, int, int>' outcome<int, int, int> m(5); ^ ~ libs/outcome/test/compile-fail/../../include/boost/outcome/outcome.hpp:222:31: note: candidate constructor (the implicit copy constructor) not viable: no known conversion from 'int' to 'const boost::outcome_v2::outcome<int, int, int, boost::outcome_v2::policy::all_narrow>' for 1st argument class BOOST_OUTCOME_NODISCARD outcome ^ Is this also a known issue? Only gcc 6 and gcc 7 with lisbtdc++ on Linux seem to pass. The other combinations I tried (clang + lisbtdc++ on Linux, Apple clang + libc++) do not. Glen

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Re: [boost] [review] outcome broken on MSVC, plus questions
by Glen Fernandes 27 Jan '18

27 Jan '18

Hi Niall, Still working on the review; I had the following questions while reading the threads: 1. Which versions of MSVC 2017 does boost-outcome not work on, right now? 2. According to the documentation, outcome and boost-outcome both require MSVC 2017, right? i.e. They do not support MSVC 2015 or lower? 3. Is standalone outcome fine with MSVC2017, only boost-outcome that is broken? 3.1. If so, is it right that the boost-outcome repository is "generated" from the outcome repository? And is that the reason that boost-outcome is broken on MSVC 2017? 4. Would you happen to know how does your outcome/result compare to Peter's outcome/result in variant2? (I saw you point out that Peter implemented expected, and then I saw he also had an outcome/result implementation in variant2). 4.1. What different compilers and standards does his support compared to yours? 4.2. What kind of code is generated from his implementation compared to yours? Thanks, Glen

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[outcome] Purpose of value_type_if_enabled?
by Bjorn Reese 27 Jan '18

27 Jan '18

Are value_type_if_enabled and error_type_if_enabled supposed to be used by the library users? If so, how?

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[spirit]why x3::alternative::parse not short-circuited?
by Larry Evans 27 Jan '18

27 Jan '18

https://github.com/boostorg/spirit/blob/develop/include/boost/spirit/home/x… shows both left.parse *and* right.parse are called. Shouldn't right.parse be skipped if left.parse succeeds?

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