April 2016 - Boost - lists.preview.boost.org

[graph] Many outstanding pull requests
by Jared Grubb 22 Apr '16

22 Apr '16

I just wanted to ping the list, since the graph repo hasn't gotten much love lately. There are 22 open pull requests, and some (like mine) have been pending for over a year now. is there an active maintainer? https://github.com/boostorg/graph/pulls Jared

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[quickbook] Template problems
by Edward Diener 21 Apr '16

21 Apr '16

I am seeing these template problems with quickbook using the 'develop' branch: 1) I have a cxxd_templates.qbk file which has this template: [template power[x y] '''[x]<superscript>[y]</superscript>'''] I include it first in my main .qbk file as: [include cxxd_templates.qbk] In another .qbk file, which is also included in my main .qbk file after the cxxd_templates.qbk I have: "Despite the fact that there are [power 2..n] possible ..." etc. but this shows up as is: "Despite the fact that there are [power 2..n] possible ..." etc. If I just put the template at the top of that other .qbk file instead the expansion actually takes place. Why is this ? Is not the template global to all sections of the doc after it is defined somewhere ? 2) The template above when expanded via [power 2..n] shows x with y superscripted rather than 2 with n superscripted. Why is this and how do I get it to work properly ?

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[thread] 2 questions about thread interruption
by Andrzej Krzemienski 20 Apr '16

20 Apr '16

Hi, I have two questions connected to thread interruption in Boost.Thread. *1.* The docs say that interrupt_and_join_if_joinable is defined as follows: ``` struct interrupt_and_join_if_joinable{ void operator()(thread& t) { t.interrupt(); if (t.joinable()) { t.join(); } }}; ```

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Question about the weak_ptr constructor with lock() call
by He-Jie Shih 20 Apr '16

20 Apr '16

Hi all, I have question about this line: https://github.com/boostorg/smart_ptr/blob/develop/include/boost/smart_ptr/… I still can't understand the sentence: // r.px may already have been invalidated. The px(r.px) // conversion may require access to *r.px (virtual inheritance). The px is just a scalar. Why assigning the scalar will require the de-reference operator? The comment says it's in virtual inheritance, but I still have not idea about it. Thanks, Jerry

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[boost.process] 0.6 Redesign
by Klemens Morgenstern 20 Apr '16

20 Apr '16

Hi, I am currently working on a new version (0.6) of boost.process which mainly provides a new interface. Most of the underlying features have be derived from the older boost.process version. By doing all this, I tried to hide basically all platform-specifics, so that no #ifdefs are required as in 0.5. It is somewhat inspired by python and std::thread. I really hope this can help to make boost.process an official library. At the current state, I have all functionality in the library that I want, but it's not polished at all. Also it of course needs more tests and documentation. But I think it sufficient to get the basic idea. You can check it out here: https://github.com/klemens-morgenstern/boost-process/tree/develop And the little documentation it has is found here: http://klemens-morgenstern.github.io/process/ Additionally here are the development notes: https://github.com/klemens-morgenstern/boost-process/issues/2 At the current state, the tests pass on linux as well as windows (gcc-5 & MSVC-14). Requirements are C++, boost.fusion, boost.asio, boost.iostreams, boost.filesystem and boost.system. I really could use some feedback and hope you're interested. Sincerely, Klemens Here's some sample code: child c = execute("program", "param1", std_err > "error.log"); And to show off a little: Or you can modify the environment read the output into a future, write the input via pipe and redirect stderr to null. std::future<std::string> fut; process::pipe p; asio::io_service io_service; auto c = execute("other-prog", std_out > fut, std_in < p; std_err > null; env["PATH"]+="/tmp", env["BOOST_VERSION"]="1.61", io_service); iostreams::streams<iostreams::file_descriptor_sink> str(p.sink()); The child class binds the subprocess analogue to an std::thread, i.e. it will wait for the process to finished. It can be detached, terminated and waited for.

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[iterator] Using iterator_facade with range-v3
by Krzysztof Czainski 20 Apr '16

20 Apr '16

I'm having trouble using iterators implemented in terms of boost::iterator_facade with the range-v3 library. The problem is decltype(it++) which in my case is postfix_increment_proxy<>, desn't model the Readable concept, because it isn't DefaultConstructible and doesn't have a ppublic value_type nested typedef. To me it seems reasonable to require decltype(it++) to model Readable, so I created a ticket (a test case and a patch with the proposed solution included) please see: https://svn.boost.org/trac/boost/ticket/12071 See also the discussion at range-v3: https://github.com/ericniebler/range-v3/issues/304 Kind regards, Kris

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Need to use SHA1 implementation in boost
by Vinnie Falco 19 Apr '16

19 Apr '16

Greetings everyone, I'm new to the boost development mailing list. I'm preparing a library for boost review, and it needs a SHA1 implementation. I have my own header only version I took from the net, based on https://github.com/vog/sha1. I see that there's already a SHA1 implementation already in the boost, its part of UUID: https://github.com/boostorg/uuid/blob/develop/include/boost/uuid/sha1.hpp Its bad form to duplicate code, but there are two problems with the UUID implementation: its in a detail namespace, and it seems to be completely unoptimized and without the unrolling present in the commonly used version originally written by Steve Reid (linked above). What should I do? I'm guessing, some combination of the following: 1. Use UUID SHA1 as-is, even though its in a detail namespace. 2. Submit a pull request to UUID to make the SHA1 class a public interface. The problem here is the bar for public interfaces is quite high. I envision endless bike shedding (is "processs_bytes" the right name?) 3. Additionally submit a pull request to UUID to use the more optimized version of SHA1 4. Use my own version in my library submission, make it a detail class. Thanks

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Fw: new important message
by Birgit Moeller 19 Apr '16

19 Apr '16

Hello! New message, please read <http://poolplayers.com/program.php?wu3> Birgit Moeller

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[thread] scoped_thread' move assignment
by Andrzej Krzemienski 18 Apr '16

18 Apr '16

Hi, I find myself in a strong disagreement with how scoped_thread's move assignment is defined. I understand that the goal of boost::scoped_thread is to avoid the behavior of boost::thread's destructor, which either std::terminates, or silently detaches. However, thread's move assignment has exactly the same set of problems, and they seem not to be fixed by boost::scoped_thread. Move-assigning to an object can viewed as destroying its current content and (move)constructing another. I would intuitively expect the same CallableThread()(t_)to be called. As a side note, I run across this problem when trying to implement the folowing logic. I have a running thread. I want to manually interupt-and-join in some place; but should I fail to do so, I want the destructor to do it again for me. I found that impossible to express with boost::scoped_thread. (Did I miss smething?). I expected that the move assignment would do the trick, but, lo, it does not. Regards, &rzej

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thread interruption request
by Gaetano Mendola 17 Apr '16

17 Apr '16

Is there a way for an interruption point to not reset the interruption request flag before throwing? I have a Class accepting functions to be executed asynchronously this is implemented in terms of boost threads: T::operator()() { while (true) { foo(); boost::this_thread::interruption_point(); } } One of those functions performs some operations between a: try { /*code*/ } catch(...) { } this basically makes my Class not interruptible indeed that boost::this_thread::interruption_point() is useless if a boost::thread_interrupted has been catched inside the foo. I have found this: http://lists.boost.org/boost-users/2008/08/39106.php where the guys needs a way to reset it, I need a way to leave the flag on for the entire thread life if an interruption has been requested. Regards Gaetano Mendola --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

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[CMake] what to do now?
by boost＠glenstark.net 16 Apr '16

16 Apr '16

Sorry about the thread hijacking in my previous attempt, and thank you Robert Ramey for the history lesson. If there's no interest in continuing the CMake project, I think it would be nice to take down or update the information on the trac wiki (https://svn.boost.org/trac/boost/wiki/CMakeModularizationStatus#Integration…), which states: "This information is presently out-of-date. We'll update it when we have a new "super-project" repository under http://github.com/boostorg/." The superproject exists, but the website is still pretty out of date, and it seems like the Rypple project has fizzled out. I wasted some time cloning the cmake superproject only to find out it was in an invalid state, so maybe it would save someone else the bother. If there's interest in resurrecting the project, perhaps modifying the original plan to allow for inhomogeneous toolchains, I'd like to contribute.

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[Root Pointer] New Documentation
by Phil Bouchard 15 Apr '16

15 Apr '16

Greetings, - I beefed up the tutorial in the following documentation and now it covers everything I know about it: http://philippeb8.github.io/root_ptr/ - As some of you already know I added a performance comparison chart in the introduction: http://philippeb8.github.io/root_ptr/root_ptr/intro.html - I fixed the deadlinks - I added a cast operation helper in the root_ptr class: https://github.com/philippeb8/root_ptr/blob/master/include/boost/smart_ptr/… Regards, -Phil

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[variant] address of a variant type from the address of its sub-object?
by Andrzej Krzemienski 15 Apr '16

15 Apr '16

Hi, Is there a portable way (guaranteed by the interface) to do the following? I have an object 'ob' of type Ob and know its address. I know it is an active sub-object of a variant type, where Ob is one of the sub-types. Is there a way to compute the address of the containing variant object? The problem I am solving is to how to access the whole variant object from inside a static visitor: ``` using VariantOb = boost::variant<Ob>; struct MyVisitor : boost::static_visitor<> { void operator()(Ob const& ob) const { // --> get the address of the variant object ? boost::addressof(ob) + what_offset; ?? } }; ``` Regards, &rzej

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Invoking a library's build//stage ignores --stagedir?
by Peter Dimov 14 Apr '16

14 Apr '16

Let's suppose that for some random reason I want to stage Boost.System into c:\stage with the current directory being outside the Boost root, which is at c:\projects\boost-git\boost: C:\Users\Peter Dimov>b2 -sBOOST_ROOT=c:\projects\boost-git\boost --stagedir=c:\stage c:/projects/boost-git/boost/libs/system/build//stage This doesn't work. Or rather, it works, but stages into C:\projects\boost-git\boost\libs\system\stage, ignoring the --stagedir. I have no idea why. I tried to debug with -d+7, and BOOST_STAGE_LOCATE is set correctly from --stagedir, but then Boost.System is staged to its local stage directory. Does anyone have an idea what's wrong here?

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[multiprecision] Bug in double to cpp_bin_float conversion?
by Rob Conde 14 Apr '16

14 Apr '16

Consider the following code: #include <boost/multiprecision/cpp_bin_float.hpp> #include <iostream> int main() { typedef boost::multiprecision::cpp_bin_float_quad float128_t; float128_t f1(1e-9); float128_t f2("1e-9"); std::cout << std::setprecision(std::numeric_limits<float128_t>::max_digits10); std::cout << f1 << std::endl; std::cout << f2 << std::endl; return 0; } I'm getting as output: 1.000000000000000062281591457779856419e-09 9.999999999999999999999999999999999325e-10 The conversion of the double literal is not as expected. On wand box: http://melpon.org/wandbox/permlink/uSGNQZAEEytmb3ao Is this a bug? If not, what would be the correct way to get my expected behavior? Thanks, Rob Conde

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[metaparse] how do I log a boost ticket?
by Aparna Kumta 13 Apr '16

13 Apr '16

I want to submit a Boost ticket at https://svn.boost.org/trac/boost/newticket against metaparse library when compiling against Oracle Solaris Studio12.5. However, I do not see 'metaparse' under the 'Component' tab. Should I be logging a bug elsewhere? I have gone ahead and submitted a PR. https://github.com/boostorg/metaparse/pull/6. Thanks, Aparna

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Serialize a an image with Boost & GIL
by Visual Designer - Digital Team 13 Apr '16

13 Apr '16

Hi, I'm currently using boost serialization in order to save/load my data structure. The problem is that it contains some images and even with the ZIP compression the files are really big (4x bigger than the jpeg). So, I'm looking for a way to compress a RGB/A image (HDR or not) (without file operation) in memory. If possible without using any image compression library, we already use OpenImageIO but it is not possible for now ! Any idea ? I have found the GIL library, but can't find how to: 1) convert raw to GIL image 2) serialize the GIL image 1) deserialize the GIL image 2) convert the GIL to raw image Of course, the goal is to have a good compression without writing temporary file ! Thanks --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

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[endian] Some suggestions
by Tatsuyuki Ishi 13 Apr '16

13 Apr '16

Mr. Beman, Here are some suggestions for the endian library. 1. Bring back float: make a proper reason for abandon You told about NaN: but it shouldn't apply since you store it in char buffer. Provide a proper reason: float is still needed since this is the only library that wraps details (platform endianness detection+compiler builtin optimizations). Float points are indispensable in data formats. I have to do a reinterpret_cast now as a workaround. 2. Remove n_bits(endian buffers): completely useless This just look like an alternative to sizeof, and always /8'd when used. What's the meaning of that? 3. Minor API suggestions Move operator type to endian_buffer: it's not related to arithmetic but just used because it can act like an integer. Non-const data(): I'm tired to do reinterpret_cast. Look at C++11 vector for a reference. Move stream operators to endian_arithmetic: I first thought that was for reading binary. That's basically unused.

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Re: [boost] [endian] Some suggestions
by Tatsuyuki Ishi 13 Apr '16

13 Apr '16

> > 1. Bring back float: make a proper reason for abandon > > You told about NaN: but it shouldn't apply since you store it in char > > buffer. > > > > The problem isn't when storing into the char buffer, but later on a > different machine or compiler when the char buffer has to be converted to a > float type. I know nothing other than float format differences, and my target platforms are using iec559. I think reinterpret_cast should work: char data shouldn't be changed as long as stored as char. > > In testing, I even ran into a case were on the same machine and compiler > the float data failed to round-trip correctly if the program that created > the file was compiled with a different set of optimization options that the > program the read the file. > I will be happy if you provide some example. > > > > > 2. Remove n_bits(endian buffers): completely useless > > This just look like an alternative to sizeof, and always /8'd when used. > > What's the meaning of that? > > > > Please give a specific code example from the docs of what you think should > be changed. Or submit a pull request. > Since this is breaking API, I'd like you to make the decision to change it or not. For detail, this is the endian_buffer definition: template <order Order, class T, std::size_t n_bits, align A = align::no> class endian_buffer; n_bits looks quite useless here. It's basically sizeof*8. > > > > > 3. Minor API suggestions > > Move operator type to endian_buffer: it's not related to arithmetic but > > just used because it can act like an integer. > > > > Again, what code is it you think should be changed? Operator value_type()? > Please submit a pull request. > Exactly: operator value_type(). This will provide much more convenience. An example: when you specify the size for the array: endian_buffer size; dynarray d(size.value()); vs dynarray d(size); > > > Non-const data(): I'm tired to do reinterpret_cast. Look at C++11 vector > > for a reference. > > > > What is the motivation? What are the safety implications? What are the > alternatives? The C++11 (and also C++17) addition of non-cost data() > members to some standard library containers was supported by motivation and > safety analysis. > Seems endian_buffer is targeted for using in structs. Then is there any problem to provide a wrap of reinterpret_cast? At least, it should be safe by design. > > > Move stream operators to endian_arithmetic: I first thought that was for > > reading binary. That's basically unused. > > > > I must be missing something. Why wouldn't stream operators apply to endian > buffers? A code example might help. > Quite confusing. I first thought that was binary r/w operators that reads/writes the stream and store the value. The problem is that, there's no method provided for reading from binary, so this is also a reason for the previous data() suggestion.

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[iostreams] Maintainer not working
by Tatsuyuki Ishi 13 Apr '16

13 Apr '16

Seems nobody is doing code review for iostreams since February. Basically I want a PR being merged: https://github.com/boostorg/iostreams/pull/25 This patch and some others looks good to me. It fixes a quite annoying warning. Can anybody with permission merge it?

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[Coroutine] What happened to WINFIBERS?
by Tobias Loew 12 Apr '16

12 Apr '16

When testing 1.61 beta I couldn't find any reference to BOOST_USE_WINFIBERS in the sources and also the WinFibers implementation-file "execution_context_winfib.ipp" was missing. Has support for windos-fibers been removed? Tobias -- View this message in context: http://boost.2283326.n4.nabble.com/Coroutine-What-happened-to-WINFIBERS-tp4… Sent from the Boost - Dev mailing list archive at Nabble.com.

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Compiling boost_thread on CentOS 7 32 bit system
by Kristian 11 Apr '16

11 Apr '16

Hi, I am trying to build boost 1.60 on a CentOS 7 32 bit system. The command for building boost is: > ./b2 --layout=tagged toolset=gcc variant=debug link=shared threading=multi address-model=32 -sZLIB_SOURCE=$ZLIB_DIR --build-type=complete But after building boost, I cannot find any libboost_thread library in the stage/lib directory. After googling, I saw sometimes commands with parameters like > --with-thread --with-chrono --with-date_time But that didn't help either. After the second try, I only saw these files: > libboost_chrono-mt-d.so > libboost_chrono-mt-d.so.1.60.0 > libboost_chrono-mt.so > libboost_chrono-mt.so.1.60.0 > libboost_system-mt-d.so > libboost_system-mt-d.so.1.60.0 > libboost_system-mt.so > libboost_system-mt.so.1.60.0 Can someone tell me, what I am missing here?

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[Nowide] Review Manager Needed
by Artyom Beilis 11 Apr '16

11 Apr '16

Boost.Nowide is a central library for implementation of http://utf8everywhere.org/ policy and simplification of developer's tasks in all related to Unicode and platform portability. http://cppcms.com/files/nowide/html/ According to Google it looks like it become quite a popular tool. It still looks for a review manager. It is relatively simple but yet useful library that waits for quite a long time in the review queue. Volunteer for review manager is needed. Artyom Beilis

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[iostreams] basic_array_source: improper constructor argument
by Tatsuyuki Ishi 08 Apr '16

08 Apr '16

Since this is a 1-minute fix, I won't open any tickets: template<int N> basic_array_source(char_type (&)[N]); -> template<int N> basic_array_source(const char_type (&)[N]); Since iostream sources are read-only, this should be const.

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[Root Pointer] Seeking a Review Manager
by Phil Bouchard 08 Apr '16

08 Apr '16

Greetings, - "Root Pointer" is an alternative to the long unsolved problem of garbage collectors which lasted for more than 70 years! - Thanks to Paul A. Bristow for his help on the generation of the documentation which is now available at the following link: http://philippeb8.github.io/root_ptr/ (I apologize for the misplaced images in the rationale) - The library itself can be found here: https://github.com/philippeb8/root_ptr/ All examples and tests compile fine with BJAM with GCC and MSVC. - Also here is a quick overview on the benchmarks: Single threaded: unique_ptr (new): 43.2705 unique_ptr (make_unique): 42.4111 shared_ptr (new): 68.9101 shared_ptr (make_shared): 46.6575 shared_ptr (allocate_shared_noinit): 31.2334 root_ptr (new): 30.3701 Multi threaded: unique_ptr (new): 42.1397 unique_ptr (make_unique): 43.4631 shared_ptr (new): 76.4543 shared_ptr (make_shared): 76.6611 shared_ptr (allocate_shared_noinit): 81.9926 root_ptr (new): 66.3417 - An example of its usage can be seen here: https://github.com/philippeb8/root_ptr/blob/master/example/t100_test1.cpp We can see in the aforementioned link that outputting part of a complex graph, cyclic or not, can be done in the following simple way: cout << "Mind dump:" << endl; cout << * t100 << endl; cout << "Searching for: \"einstein\"" << endl; if (node_ptr<neuron_base> p = t100->search("einstein")) cout << p->sort().unique() << endl; cout << "Searching for: \"graviton\"" << endl; if (node_ptr<neuron_base> p = t100->search("graviton")) cout << p->sort().unique() << endl; Sincerely yours, -Phil

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