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

Re: [boost] Proposed SG14 <system_error2> ready for feedback
by Bjorn Reese 04 Mar '18

04 Mar '18

On 02/28/18 23:10, Niall Douglas via Boost wrote: > 7. `std::error_code` enforced its value to always be an `int`. This is > problematic for coding systems which might use a `long` and implement > coding namespaces within the extended number of bits, or for end users > wishing to combine a code with a `void *` in order to transmit payload > or additional context. As a result, `status_code` is templated to its > domain, and the domain sets its type. A type erased edition of > `status_code<D>` is available as `status_code<void>`, this is for > obvious reasons non-copyable, non-movable and non-destructible. > > A more useful type erased edition is `status_code<erased<T>>` > which is available if `D::value_type` is trivially copyable, `T` is an > integral type, and `sizeof(T) >= sizeof(D::value_type)`. This lets you > use `status_code<erased<T>>` in all your public interfaces without > restrictions. As a pointer to the original category is retained, and > trivially copyable types may be legally copied by `memcpy()`, type > erased status codes work exactly as normal, except that publicly it does > not advertise its type. While I do see the need for providing extensions, I am not sure if status_code<void> is useful given all its "non-" characteristics. Can you elaborate on its use-cases? I propose that the customizable status_code<D> is renamed to basic_status_code<D>. In keeping with the pre-established practices of std::error_code using int, I furthermore suggest that status_code becomes a non-templated alias for basic_status_code<int>.

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Gsoc2018/Mentor required.
by nivyatheresa 04 Mar '18

04 Mar '18

Hi, I am Nivya Theresa Jose, b-tech student from Indian Institute of Technology Roorkee. I would like to contribute to boost.uBLAS project 1, which is to add support for tensors .I would like to connect with a mentor and would like to know about further procedures. Thanks in advance, sincerely, Nivya Theresa Jose. -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Dev-f2600599.html

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Help/Mentor required
by Devika Krishnadas 04 Mar '18

04 Mar '18

Hi, I am Devika Krishnadas, an Undergrad Computer Science student from Amrita University. I am interested in contributing to boost.uBLAS project #1, which is to add Statistics and Machine learning functions. It would be great if anyone could help me proceed further. Thanks in advance, Regards, Devika Krishnads.

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gsoc2018 inquiry and mentor seeking
by fady esam 04 Mar '18

04 Mar '18

Hello, I am Fady Esam student at 3rd year of computer engineering in ASU university in Egypt I want to cobtribute the the project of "Adding multicore and gpu computations to uBLAS" As i was the team leader and main contributer in an open source library for complex-numbers matrices that has the same parsing and interface as matlab and supports all operations like computing inverse by gaussian elimination and determinant by LU decomposition and +, - , * ,/ , .* , ./ and computing power of matrix in a very optimized way That's a github link to the library : https://github.com/boostorg/boost/wiki/Boost-Google-Summer-of-Code-2018 I want to know do i have to implement part of the library again in template for the competency test? And is there a mentor that is interested so i can submit a proposal to? Thanks for reading :)

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[interprocess] file_mutex class proposal
by mateusz janek 04 Mar '18

04 Mar '18

Hello boost::interprocess community, During my pet projects development I found that a file access synchronization is a common problem so, I wrote a class that wraps it and thought that it can be useful for wider community. I would like to ask you what do you think about such functionality in boost::interprocess? I'm aware that class from the repo is not ready to release. Just wanted to show about what functionality I'm talking about. Here you can find the repo: https://github.com/stryku/file_mutex You can find there the proposed class and a simple usage example. If you will find it interesting I will prepare more formal merge proposal, update docs, maybe more examples etc. Looking forward to hearing from you what do you think about it. Thank you, Mateusz Janek

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Which headers to include?
by Lakshay Garg 03 Mar '18

03 Mar '18

Hello Boost I am using a few Boost libraries in a project I am working on. I must confess that this is perhaps my first serious use of boost so all this could just be due to lack of familiarity. The one thing that keeps frustrating me about boost is finding out _which headers to include?_ I am not sure if this is a problem with my googling skills or library documentation or maybe I just don't know the proper place to look at but most of the times I need to use a library with lots of headers (I am looking at Boost.Log) I have to go grepping the boost code. Is there something I am missing or is there a better way to go about this problem? Lakshay

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why boost does not have skip list implementation?
by David Frank 03 Mar '18

03 Mar '18

like java concurrentSkipListSet for example. Thanks, David

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past few days coding:=>>makefile generator
by Ggh 03 Mar '18

03 Mar '18

#-------------------------------------------------------------------------------- # # Command Line Options: # # For each argument add a space between the switch and the argument to the switch, # e.g.: # # mkmakefile -tt exe -t targetname # # mkmakefile --help # # -tt <exe|dynamic|objs|static> Target type # -t <targetname> Target name # -i <include directory> Include directory # Include directories can be several. Prepend # each directory with an '-i' # -L <library directory> Library directory # Library directories may also be several, prepend each # directory with an '-L' # -l <library name> Library name, may also be several, prepend each # library with '-l'. # -d <define> Define # May also be several, prepend each define with '-d'. # -hd Header dependencies # This flag makes the generator scan # the source files for header files # included. Creates dependency rules # in the generated makefile. # If a header file is included in a source file # and found in any of the include directories given # it will be listed as a dependency to the source file. # -o <makefile filename> Makefile filename to generate # -c <c compiler> C compiler, the compiler needs to be in the PATH # environment variable. # -cc <c++ compiler> C++ compiler, the C++ compiler needs to be in # the PATH environment variable aswell. # -sl <static library> Link to static library # The number of static libraries can be any. # Prepend each library name with an '-sl' tag. # -wd <target directory> Target directory. The program changes # to the target directory, creates the makefile # and reverts back to the directory it was # started from. The makefile is written # to the target directory. If this argument is # not set then the current directory will be used. # -mk Make the program / library. This option executes # 'make' with the make file given. If no makefile # argument is given it will use 'makefile.mk' by # default # # -help This help information # #--------------------------------------------------------------------------------

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[gsoc18]project1-1: Add statistics and machine learning functions
by SheldonZhang 02 Mar '18

02 Mar '18

Hi, My name is Zhang Bohan(Sheldon Zhang) from China. I am a freshman in Beijing University of Posts and Telecommunications, majoring in Information and Communication Engineering. I want a mentor who can guide me to accomplish the project. I am interested in working for Boost.uBLAS because in my profession there are plenty of calculation about matrix. I believe this will lead me to better understanding about it. And I love machine learning, it is the way to the future. I am taking a machine learning course(taught by Andrew Ng) on coursea. So I know what I am going to do in the project. I do quite well in Linear Algebra. In the exam, I got top 10% in the grade. I have been programming since junior high school. I am familiar to C++-11 and its features(like lambdas and template). I have good command of basic algorithms. I participated in National Olympiad in Informatics and got good grades. Besides, I am a teaching assistant in Program Designing Course. I am googd at English, so there is few difficulty in communicating. I have done the programming competency test https://github.com/ltg001/gsoc18-codeCompetencyTest At last, what should I do in this period? With regard, Sheldon Zhang -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Dev-f2600599.html

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[gsoc18] [Boost.Real] Competency Test
by Parth Mittal 02 Mar '18

02 Mar '18

Hi My name is Parth Mittal, and I'm a third year computer science undergraduate. Here is my attempt at the competency test: (wrt the first, second, and third bullet on the project page) 1. I uploaded my code here (https://github.com/parthmittal/boost_competency_test) I'm not sure how much of it is required to be functional but (of course) I can write more code if required. The current code uses an std::pair of the chosen rational type to represent intervals, it is probably more sensible to replace this with a dedicated type for intervals. Also I have two different ideas for dealing with integers in the binary operators: (i) Wrap them into a "real" number (with an approximation function that always returns the exact value and an error term of 0). (ii) Add a facility for additive and multiplicative rational factors to the class. 2. For sure there is no way to be sure two numbers are equal in finite time, so while checking if a and b are equal, we should pass an integer parameter, say K, and then for every pair of integers i, j between 1 and K, we should check if a(i) = b(j) (of course a(i) = b(j) iff the intervals share a point). This feels somewhat inefficient (it would be nice to eliminate the quadratic runtime with K), but since we don't have a guarantee that a(i + 1) is a subset of a(i), I don't see any obvious way to improve this. 3. To be honest, I had to google for "Small String Optimization" - and the analogue I can see is to store as an array the values of a(k) for all k <= K for some small constant K. I'm not sure how to implement this at compile time; it makes sense that the approximation function(s) for the real number involved be constexpr, but I've never written any code which is constexpr. Perhaps my code in (1) already makes this clear, but I'm not very experienced at writing C++; I've written probably 100k+ lines while doing programming contests, but this was rather simple code which was written once and read never. I can fill in the gaps in my knowledge of the language on an ad-hoc basis (or using the time until the SoC officially begins). Thank you for reading Parth Mittal

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