January 2018 - Boost - lists.preview.boost.org

CMake Announcement from Boost Steering Committee
by Jon Kalb 13 Aug '24

13 Aug '24

The libraries produced by the Boost community have had a greater impact on the way that the C++ community writes code than any other library implementation. The focus of the Boost community will always be on the libraries, but it is undeniable that we are dependent on and often limited by the infrastructure of our trade. Years ago, the move to Git was contentious; yet, it was required to improve development. In a similar vein our build system has become an impediment for many developers and users, existing and prospective. Therefore, we, the Steering Committee, announce to the Boost community our desire and intent to move Boost’s build system to CMake for users and developers alike. We are soliciting comments and proposals from the community to guide the process and the goals. Our desire is that the community can come to consensus by the end of the calendar year with a vision of supporting users and developers. We understand that the actual process of achieving the end goal will be long, time consuming, and not without its share of conflict. We also recognize that the Boost community is comprised of bright and passionate individuals that are eager to get involved and help get work done. The members of the Steering Committee have been encouraged by the discussions and activity surrounding CMake on the mailing lists over the years and know that many people have voiced visions. We hope that each of you rejoins the discussion to support this initiative and contributes to the common goal of improving Boost’s integration into the broader C++ ecosystem. For the Boost Steering Committee, Jon Kalb, Chair jonkalb(a)boost.org

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[foreach][polygon][xpressive][bimap][ptr_container][gil][assign][typeof][msm] PRs for removing executable attribute for files
by Edward Diener 08 Mar '18

08 Mar '18

The following libraries still have PRs, which I have previously submitted, for removing the executable attribute for one or more files: foreach polygon xpressive bimap ptr_container gil assign typeof msm None of these PRs affect anything other than the file attribute, so no testing is needed AFAICS since no code changes. If the maintainers of the above libraries, or someone else with write access to these libraries, can merge the appropriate PR to 'develop', and then merge 'develop' to 'master', we can get rid of having any files with their executable attribute set in the next release.

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[yap] Re-announcing Yap
by Zach Laine 23 Feb '18

23 Feb '18

I posted 2-3 months ago about Yap, an expression template library I've written that I intend to propose for Boost. This is just a reminder that the library exists, and where to find it. I'm giving a talk about it at C++Now 2017, and some time after that I intend to submit it to the queue. Louis Dionne has offered to serve as review manager when the time comes. You can find the main repo on GitHub: https://github.com/tzlaine/yap And online docs are here: https://tzlaine.github.io/yap Zach

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Query for interest in library: reflective enum
by Nir Friedman 23 Feb '18

23 Feb '18

Hello, I recently needed a reflective enum for work (that is an enum where you can programmatically convert to and from strings, know how many enumerators there are, and iterate over all enumerators). I looked online but I didn't find anything that met my requirements. I was surprised that there wasn't one in Boost. So I'd like to see if there is interest; I wrote an implementation that I think has several nice features. The most polished existing smart enum implementation I could find was http://aantron.github.io/better-enums/. However, the enum implemented there is not a true enum; it uses a nested member of a class kind of approach. So for example, the is_enum type trait will not recognize is as an enum. You cannot use it as a non-type template parameter. I strongly think that a good generic smart enum macro should generate the exact "vanilla" enum (or enum class) declaration. My library's syntax looks like this: WISE_ENUM(Foo, BAR, (BAZ, 3)) This generates, among other things, exactly: enum Foo { BAR, BAZ=3}; I intend this as an explicit guarantee of the library that the programmer can count on. That way when Foo is used for things unrelating to reflection, the developer can be confident that there will not be any surprises. Beyond compatability with C++ facilities for enums, and minimizing surprise, another advantage of this approach is that it's guaranteed to be backwards compatible. An existing codebase with an existing enum/enum class can switch to this smart enum with very high confidence that existing code will continue to work as before. The WISE_ENUM macro, beyond generating the vanilla enum, also generates a switch-case function for to-string conversion (for maximal efficiency), and finally it generates a constexpr function that returns a std::array<std::pair<const char*, Foo>> listing all of the arrays and their string descriptions. This constexpr function, which is found via ADL, allows writing a sequence of (constexpr) variables and functions providing the rest of the desired functionality. Usage looks like this: std::cerr << "My enum's size is : " << wise_enum::size<Foo> // this is constexpr template variable auto x = wise_enum::from_string<Foo>("BAR").value(); // from_string returns an optional auto y = wise_enum::to_string(x); // y is string literal, no heap allocation My implementation (POC level) is here: https://github.com/quicknir/wise_enum. I don't yet have separate macros to cover enum/enum class/explicit/implicit backing type combinations. It's only about 100 lines of code, leaning heavily on BOOST_PP to do the heavy lifting. It requires variadic macros, and can probably target C++11 (if it doesn't already). I probably need to "comma harden" the macros for bizarre stuff like WISE_ENUM(Foo, (BAR, my_func<3,4>())). It has the limitation that the macro cannot be used inside a class (this is hard to workaround for reflective macros). It's also unclear how repeated enumeration values would be handled (enum Foo { BAR = 1, BAZ = 1}). As it stands this will cause a compilation failure in the generated switch case of the to_string function. Can discuss more in subsequent emails. One suggested feature is an is_contiguous trait. Another reasonable bit of functionality might be an is_wise_enum trait. Version 2 of this library could target enum sets. Although it's not fancy, I think this nicely covers a piece of functionality I often need, and it does so avoiding any downside compared to using a simple enum (beyond having to use macros). Hope other people will agree! Cheers, Nir

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[release notes] Linking to github issues/pull requests
by Daniel James 14 Feb '18

14 Feb '18

Hi, I've added templates for linking to github issues and pull requests from the release notes. There are two templates: [github module number] which expands to '#number' [github_pr module number] which expands to 'PR#number'. Both will be linked, they need the name of the module to link to the right place. We only really need the issue template as github redirects to the pull request if appropriate, but existing release notes have been using the PR#3 format, so I thought it should support that. You can see an example in the unordered release notes for 1.67.0: https://github.com/boostorg/website/blob/master/feed/history/boost_1_67_0.q… http://www.boost.org/users/history/in_progress.html Does that look okay? Daniel

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[review] Review of Outcome v2 (Fri-19-Jan to Sun-28-Jan, 2018)
by charleyb123 . 09 Feb '18

09 Feb '18

Hi, Everyone, The formal review of Niall Douglas' Outcome (v2) library begins Fri-19-Jan and continues until Sun-28-Jan, 2018. Your participation is encouraged, as the proposed library is uncoupled and focused, and reviewers do not need to be domain experts to appreciate the potential usefulness of the library and to propose improvements. Everyone needs (and has suffered) error handling, and can compose an opinion on that topic. Outcome is a header-only C++14 library providing expressive and very lightweight 'outcome<T>' and 'result<T>' error handling, suitable for low-latency code bases. The library further provides mechanisms for wrapping '<success|error|exception>' state to safely wrap throwing APIs; and poses an idiom of, "islands of exception in a sea of noexcept". Key features: *- Makes using 'std::error_code' from C++11's <system_error> more convenient and safe *- Good focus on low-latency (with tests and benchmarks) *- Error-handling algorithmic composition with-or-without C++ exceptions enabled *- Dependency only on Boost Recall a previous Outcome (v1) Boost Review occurred 19-May to 02-June 2017: *- Outcome (v1) Review Report: *- https://lists.boost.org/Archives/boost/2017/06/235783.php This review for Outcome (v2) includes significant changes as a result of feedback from the Outcome (v1) review. For a list of changes (v1==>v2), see: *- https://github.com/ned14/outcome#changes-since-v1 Reference API docs: *- https://ned14.github.io/outcome/reference/ GitHub: *- https://github.com/ned14/boost-outcome Tarball: *- https://github.com/ned14/boost-outcome/releases/tag/v2. 0-boost-peer-review Online "play-pen" (try it out!): *- https://wandbox.org/permlink/Ji1khzyxoAR0LJQC YOUR REVIEW --------------------- Please post your comments and review to the boost mailing list (preferably), or privately to the Review Manager (to me ;-). Here are some questions you might want to answer in your 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: - Do you think the library should be accepted as a Boost library? For more information about Boost Formal Review Process, see: http://www.boost.org/community/reviews.html Thank you very much for your time and efforts. --charley Outcome (v2) Review Manager

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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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[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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[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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