August 2013 - Boost - lists.boost.org

[Asio] Commit-rollback on asynchronous operations - cancel / close may fail
by Sorin Fetche 15 Aug '13

15 Aug '13

Hi, I noticed that functions for canceling asynchronous operations or closing objects on which they are executed are documented as being possible to fail. This is the case at least for the acceptor objects (basic_socket_acceptor or ip::tcp::acceptor), socket objects (basic_socket or ip::tcp::socket) and even timer objects (deadline_timer or steady_timer). In this case what are the options for implementing commit-rollback for asynchronous operations? By rollback I mean canceling a successfully started first operation in case a second operation in the batch of operations fails (as exemplified in the attached test code). As described in [1] a rollback operation absolutely relies on no-throw operations. What is supposed to happen with the handler associated with the asynchronous operation that failed to be canceled? Handlers, most often, at least for non-trivial programs are carrying shared resources with them and, if not called, may leave the application in a hanged state waiting for an event that will never come. I didn't find in the documentation any guarantees given regarding the handlers associated with the async-operations that they can or cannot be lost (that is never called). This of course, as long as io_service::run is running or the control returns to it after an exception. Also, as shown in [2] and as demonstrated by the attached test program, at least for async_write, invoking the destructor of an object on top of which asynchronous operations are being executed is not correct either and may lead to undefined behavior (crash). [1] Exception-Safety in Generic Components; section 6 http://www.boost.org/community/exception_safety.html [2] BoostCon 2011: Thinking Asynchronously; slide 47 https://github.com/boostcon/2011_presentations/raw/master/mon/thinking_asyn… Thank you, Sorin Fetche

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[serialization] How are floating point values handled?
by John Maddock 14 Aug '13

14 Aug '13

I can't find anything in the docs about how floating point types are handled by the serialization lib. It seems like text archives print however many digits are specified in the ostream's precision is that correct? If so I think this needs to be raised as a big red flag, because it means that floating point values, uniquely compared to other primitives, do not round trip by default. Except actually they do when using a binary archive. This actually raises a problem when using text archives with floating point data - if you want to be able to round trip the values, then how many digits precision should you set the stream to? Particularly if you're saving a complex structure containing different floating point types of differing precisions? I would have thought it would be better for the serialization lib to set the stream precision before outputting a primitive type - to std::numeric_limits<T>::max_digits10 (or std::numeric_limits<T>::digits10+2 if max_digits10 is not available). However, I recognize that this is a difficult issue! Cheers, John.

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Pre-build MSVC Boost binaries
by Fredrik Orderud 13 Aug '13

13 Aug '13

Over the last year, I've set up a small SourceForge "WinBin" project [1] for distributing Microsoft Windows binaries for Boost (and some other projects). The repository is sorted by Boost version, compiler version and shared vs. static linking. Each file archive contains pre-build boost in debug/release for both 32/64-bit, following a include/lib[64]/bin[64] folder structure. There also seems to be some other sources for pre-built boost around (e.g. https://sourceforge.net/projects/boost/files/boost-binaries/ and http://boost.teeks99.com/bin/) However, these do not seem to provide boost built for both static and shared linking. Also, they do not appear to adhere to the "quasi standard" include/lib[64]/bin[64] folder naming convention used by many libraries. Finally, they seem to lack information on which version of python (and possibly other 3rd party SW) they are compiled against. Therefore, I decided to set up my own boost-binaries webpage. Please let me know if you might be interested in either improving the "WinBin" project, or somehow joining forces to merge the various sources of Boost binaries into a single, more "authoritative" repository. I would be more than happy to shut WinBin down if "similar enough" binaries can be downloaded elsewhere. Thanks in advance, Fredrik Orderud [1] https://sourceforge.net/projects/winbin/files/boost/

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[utility] Fixes to value_init docs
by Robert Kawulak 13 Aug '13

13 Aug '13

I've made some small fixes to value_init docs (patch attached) that I want to commit. Any objections? Best regards, Robert

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Line endings fixes
by Vitaly Budovski 13 Aug '13

13 Aug '13

Hi, Please see the attached files. boost_endings1.patch just sets some of the cpp and other text files to have file endings consistent with the rest of the repository. boost_endings2.patch may be controversial as it does the same but for the svg files. Some of them are marked as text, others as binary. It's a real mess. Most of the svg files are generated from other sources so should probably be omitted from the repository and simply regenerated when docs are built. Came across these issues when checking out the modularised boost git repository. Regards, Vitaly

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unique_ptr for C++03
by Andrew Ho 13 Aug '13

13 Aug '13

Hi, I implemented std::unique_ptr using C++03 features plus a few other Boost Libraries. Incidentally, I also implemented default_delete (which binds to std::default_delete if available) because it's required for unique_ptr. https://github.com/helloworld922/unique_ptr The library binds to std::unique_ptr if standard library support is available. There are a few things I don't think I'll be able to emulate exactly. Namely: - I don't think the deleter can ever be forwarded correctly (limitation of C++03). Ideas/suggestions for how to best handle this are welcome (currently, I move the deleter if E == D and copy otherwise, I think) - There's no explicit conversion overloads in C++03. Currently I have operator bool() implemented non-explicitly if there's no compiler support, relying on the user to only use it "as-if explicit". An alternative solution is to remove the typecast operator and force users to use get() == NULL_VALUE. - functions relying on nullptr_t are only enabled if compiler support is available. Again, I don't think there's any possible work-around for C++03. There are also a few missing features (still working on the implementation): - make_unique (part of c++14) - nullptr_t comparison operators Current dependencies (assuming no C++11 std::unique_ptr): - Boost.Config - Boost.Move - Boost.TypeTraits Comments/Feedback is welcome.

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Location for library-specific utility files in Subversion trunk
by Jeremiah Willcock 12 Aug '13

12 Aug '13

I have a file containing the list of unmerged changes from BGL and some command lines to simplify merging changes from the trunk to the release branch and to help in writing release notes. They are not useful to have in a release, but I would like to have them stored somewhere other than just my home directory. Is there a path designated for that? Somewhere inside tools/release/? -- Jeremiah Willcock

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Inspection report: revision used?
by Joaquin M Lopez Munoz 11 Aug '13

11 Aug '13

Hi, The current inspection report, dated 15:30:32 UTC, Saturday 10 August 2013: http://boost.cowic.de/rc/docs-inspect-release.html fails to state the SVN revision being inspected The files checked were from unknown at revision unknown As it happens, whatever revision of the code is being used it has to be older than Aug 10, since the error reported at http://boost.cowic.de/rc/docs-inspect-release.html#flyweight has been fixed as of Aug 6, i.e. four days before: https://svn.boost.org/trac/boost/changeset/85227 Just a heads up in case there's something to fix on the inspection report running engine. Joaquín M López Muñoz Telefónica Digital

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[mixin] New library reminder
by Borislav Stanimirov 11 Aug '13

11 Aug '13

Hello, Some of you might remember the previous discussion on the subject (archived here: http://lists.boost.org/Archives/boost/2013/01/200598.php) Anyway, in short, I'm developing a library with the intention to formally submit it to Boost by the end of the year. You can find it here: https://github.com/iboB/boost.mixin The latest news about it is that I think that the library's features for the formal submission are done and all that's left are minor tweaks, bug fixes, tests, examples, and, most importantly, a complete documentation. In the meantime, I again invite you all to check it out. Any comments, suggestions, and questions will be greatly appreciated. Thanks, -- Borislav

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Fwd: Line endings fixes
by Vitaly Budovski 11 Aug '13

11 Aug '13

Hi, On 10 Aug 2013 18:55, "Paul A. Bristow" <pbristow(a)hetp.u-net.com> wrote: > > I'm confused, but does it help you to know that the many SVG files for Booth.Math are generated by a > C++ program that we run. > > This program writes html and end of line as std::endl;. > Regardless of the method, any text based formats should be checked into SVN with mime-type text/plain and native eol. > These SVG files are used to generate the PDF version of Boost.Math docs (because using PNG produces > very poor display). > No disagreement about SVG being the better choice where possible. > These SVG files are also converted to PNG for the html version. > <snip> > > HTH > > Paul Cheers, Vitaly

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