June 2014 - Boost - lists.preview.boost.org

[core] Breaking bugfix in scoped enums
by Andrey Semashev 07 Jun '14

07 Jun '14

Hi, While creating tests for scoped enums emulation I've fixed a bug which resulted in the enums being convertible to int. This is a potentially breaking change, the code like this will now not compile: BOOST_SCOPED_ENUM_DECLARE_BEGIN(color) { red, green, blue } BOOST_SCOPED_ENUM_DECLARE_END(color) void foo(boost::native_type<color>::type col); color col = color::blue; foo(col); The call to foo() should be done like this: foo(boost::native_value(col)); Previously, the conversion was implicit.

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[pimpl] Some comments
by Andrzej Krzemienski 07 Jun '14

07 Jun '14

Hi Vladimir, My congratulations on the success of Boost.Convert. But I can see you will not have much time to celebrate it, next library waiting in the queue. I wanted to share some of my thoughts on Boost.Pimpl library. This is by no means a review. I am not sure if I will have time to do a decent one. I only skipped through the documentation so my understanding is superficial, but I noticed some things that raise my immediate objection. Boost.Pimpl has been around for a while now, and I remember I was using it at some point in my work, although it didn't have the nice documentation format at that time. [1] The main point in using pimpl idiom (at least my) is to avoid header inclusion, which may grow compilation time too much (at the expense of certain run-time cost). But in order to use Boost.Pimpl I do need to include a header file, which in turn includes more header files. This is arguably less headers that in normal non-pimpl implementation, but it is more than if I used a raw pointer. And this is what I finally did in my work: switched to raw pointers for implementing piml in order to get the build perform faster. (I didn't measure the improvement though.) [2] Boost.Pimpl is good for everyone: people who like value semantics get the value semantic interface, and people who like shated_ptr's get shared_ptr semantics. Call me selfish or biased, but I believe using shared_ptr's should be banned (at least in 90% of the cases where it is currently being used), and the fact that you advertise it first in the docs makes me uneasy. It looks from the docs that 'pointer_semantics' implements something like a flyweight. This is so against value semantics. One of the expectations of types returned by value is that changing the original does no affect the copy: T a = c; T b = c; zap(a); assert(b==c && a!=b); Although the author of class Book knows that it is implemented with pointer_semantics, the users of the class are likely not to know it, and since Book doesn't look like a pointer, they will be expecting value semantics, and will be severely punished. [3] The docs advertize the definition of operator== as a member function. This is against a typical recommendation that it should be a free function in order to avoid asymmetrical behavior in certain cases. Does your library allow the definition of a non-member operator==? If so, I would encourage you to reflect that in the docs. [4] This page: http://yet-another-user.github.io/boost.pimpl/the_boost_pimpl_library/pimpl… says "The advantage of the 'built-in' *Book::null()* [...] is that it makes possible an implementation of strongly exception-safe constructors, the copy constructor" There seems to be something wrong with this statement. How can a strong (commit-or-rollback) guarantee apply to constructors? If an exception is thrown from constructor the object is never created or accessible, so no-one cares about its state (as long as it doesn't leak). Or did you mean the no-throw guarantee? But the latter looks like an anti pattern. What is the value in concealing the exception (and information it carries) and instead produce null objects, which cannot be used? While I find the value_semantics interface useful, I am strongly against even offering the pointer_semantics interface. I am not sure if I have succeeded in explaining why. Regards, &rzej

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[modularization] Extracting lexical_cast from conversion
by Vicente J. Botet Escriba 07 Jun '14

07 Jun '14

Conversion depends on Math and Range due to lexical_cast. /math/ <http://www.pdimov.com/tmp/report-6d1f271/math.html> |<boost/math/special_functions/fpclassify.hpp>| * from |<boost/lexical_cast.hpp>| |<boost/math/special_functions/sign.hpp>| * from |<boost/lexical_cast.hpp>| /range/ <http://www.pdimov.com/tmp/report-6d1f271/range.html> |<boost/range/iterator_range_core.hpp>| * from |<boost/lexical_cast.hpp>| |Extracting LexicalCast allows to break these cycle|s Conversion -> Math -> Conversion -> Range -> Conversion Best, Vicente P.S. This dependencies have been introduced lately while trying to make the implementation more efficient.

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HTTP SERVER 2 Question!
by zyf01234＠gmail.com 07 Jun '14

07 Jun '14

I'm trying to test the HTTP SERVER 2 of the boost.asio samples. some question comes to my mind,so can anyone give me a hand? Q1. The code acceptor_(io_service_pool_.get_io_service()) means get one io_service from the pool , but to this application only one acceptor is created and one io_service is running? Q2 It takes about 25% of the CPU occupancy rate , this is caused by the Q1? zyf01234(a)gmail.com

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Running Tests with Timeouts
by Axel Ismirlian 07 Jun '14

07 Jun '14

Hello everyone, Is there a way to run all of the tests on all of the test suites with timeouts? Occasionally, I need to run all of the tests on all of the test suites, so I leave them overnight only to find out the next morning that one of them hung forever. Sincerely, -Axel

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Review manager for Boost QVM?
by Emil Dotchevski 06 Jun '14

06 Jun '14

Hello, The QVM library has been in the review queue for a some time waiting for a review manager. I've been receiving occasional support requests from random people, and I remember there was at least some initial interest when I proposed the library years ago, but nobody has volunteered to be the review manager yet. This is a library for working with (Q)uaternions and statically-sized (V)ectors and (M)atrices, it's the kind of high level library that is useful to video game programers working with 3D graphics. It's unique (AFAIK) feature is that it uses a type traits system that allows all library functions to operate on 3rd-party types, making it easy to integrate types from different other math libraries into a single type-safe environment. It also has functions that can map vectors as matrices or matrix rows/columns as vectors, or even present mutable transposed view to any matrix, all without creating temporary objects. The documentation and source code can be found here: http://www.revergestudios.com/boost-qvm/ Anyone takers? :) -- Emil Dotchevski Reverge Studios, Inc. http://www.revergestudios.com/reblog/index.php?n=ReCode

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[modularization] About sub-sub-module path/names..
by Rene Rivera 06 Jun '14

06 Jun '14

This past week I spent time to update my documentation tools to the latest to get the Predef release done. As part of that I created my own mini-Boost that is both minimal to just getting Quickbook compiled and I can control when updating <https://github.com/grafikrobot/boost-doctools/tree/develop>. One frustrating aspect of building that repo was that I made various accidents in adding submodules because of naming. And a key one was the structure for the numeric submodules <https://github.com/boostorg/boost/tree/develop/libs/numeric>. So I have one basic question: Is there a *good* reason why numeric submodules need to have their own subdirectory? It would seem to me much easier to understand if all submodules where flat and on the libs/* dir. The uniformity would also remove various special cases I saw in build and testing code files. For example some special code in Boost/Jamroot <https://github.com/boostorg/boost/blob/develop/Jamroot#L149>. -- -- Rene Rivera -- Grafik - Don't Assume Anything -- Robot Dreams - http://robot-dreams.net -- rrivera/acm.org (msn) - grafikrobot/aim,yahoo,skype,efnet,gmail

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[core] Detach demangle() from type_info
by Andrey Semashev 06 Jun '14

06 Jun '14

Hi Peter, I can see you already extracted demangle() to boost/core. Great, thanks! However I'd prefer it to be detached from type_info. This tool would be useful with different kinds of symbols, like function and variable names, not just type_info. So it better accept a string as an argument and not type_info. demangled_name() should probably be in core/typeinfo.hpp. And regarding typeinfo.hpp. Aren't we duplicating Boost.TypeIndex here? PS: I was also planning to create pull requests to other libraries to use demangle from Core. These are Exception, Units, TypeIndex and Log, AFAIK. Do you plan to do this? If not, I could.

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[Modularization] unique_ptr (interprocess/smart_ptr) and SmartPtr
by Vicente J. Botet Escriba 06 Jun '14

06 Jun '14

Hi, what about moving|boost/interprocess/smart_ptr/* to module SmartPtr?| || |||| |||Vicente| ||

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Re: [boost] [pimpl] No documentation for pointer semant
by Dave Gomboc 06 Jun '14

06 Jun '14

[Paul A Bristow]: > I unhappy with a review rigid policy that nothing can be changed during a > review. It isn't always helpful. > > We never accept anything without requiring some changes? > > Can we instead now use git's easy branches to specify a fixed 'master' branch, > but allow the author to update a 'develop' branch as the review develops? [Edward Diener]: > I believe that changes can be made to a reviewed library during a review > as long as the 'master' branch does not change. After all we want all > reviewers to be looking at the same 'master' branch as the code to be > reviewed. But if the developer wants to make changes to other branches > during the review I think this should be allowed. May I suggest that either the library author or the review manager ought to, near the commencement of the review, identify a specific version to be reviewed? This is quite distinct from identifying a branch name for a conventional branch such as master that is expected to change frequently even over a two-week period. A specific checkout is typically identified by a SHA: a branch name such as 'master' is primarily just an alias to the SHA to which it currently resolves. Then again, Boost is relatively new to using git, so perhaps a new branch name can be introduced to refer specifically to the review version. The review manager could, at the commencement of the review, specify the checkout instructions using a specific SHA. For example, for Boost.Pimpl, the manager would provide Source: https://github.com/yet-another-user/boost.pimpl, SHA 59a5c0d or, in command-line-ese, git clone https://github.com/yet-another-user/boost.pimpl git reset --hard 59a5c0d As I mentioned, not everybody may be comfortable working directly with SHAs immediately, so the library author and/or the review manager may wish to introduce a specific label for the purpose of easing identifying the review version. If one of them (or somebody else with write access to the repository) continues from the above two commands with the further git checkout -b boost_review git push origin boost_review then it still becomes possible for the contents of the master branch to change (which, generally speaking, is highly desirable) without disrupting the review process. In this case, the instructions provided by the manager could be: Source: https://github.com/yet-another-user/boost.pimpl, branch boost_review or, in command-line-ese, git clone https://github.com/yet-another-user/boost.pimpl git checkout boost_review which should be more palatable to the large group of people migrating from Subversion. Naturally, in this case it is imperative that boost_review not itself be pushed to further during the review. However, there is no reason the library author from continuing with these commands: git checkout -b boost_review_fixes git push -u origin boost_review_fixes at which point, fixes to items that come up in the review can be pushed onto that branch, and those people who specifically want to take a look at the fixes can easily do so. The above said, the long-term simplicity of specifying a SHA directly instead of a branch at all is not only that one doesn't have to go and make a bunch of new branch names in order to continue development, but even more importantly, one can't push to a SHA to change its contents --because modifying a commit after the fact modifies its SHA also -- so everyone is sure to get the same version of the content being reviewed. Dave

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