- Boost - lists.boost.org

using of circular_buffer
by news.gmane.org 28 Mar '12

28 Mar '12

Hello there, i am new here and i just want to say "hi". so, i'm using boost almost a year now, usually i just used the array component. latley i wanted to implement the circular_buffer. i've defined it in a class after the private-modifier like this: boost::circular_buffer<std::string> textBuffer(10); (as take from the documentation) but my compiler on minGW will throw an error. so, i guess i got something wrong in declaring a string-textbuffer with the lenght of 10?! in the boost-docs there is following example: boost::circular_buffer<int> cb(3); help is appreciated, best would be a working example and a little hint which information is may have missed. greetings tony

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Fwd: [Boost-bugs] [Boost C++ Libraries] #380: Support for bundled properties in graph adaptors
by Marshall Clow 28 Mar '12

28 Mar '12

I just wanted everyone to notice that Jeremiah just closed a _seven year old_ bug in boost. -- Marshall Begin forwarded message: > From: "Boost C++ Libraries" <noreply(a)lists.boost.org> > Subject: Re: [Boost-bugs] [Boost C++ Libraries] #380: Support for bundled properties in graph adaptors > Date: March 28, 2012 1:47:03 PM PDT > Cc: boost-bugs(a)lists.boost.org > Reply-To: boost(a)lists.boost.org > > #380: Support for bundled properties in graph adaptors > -----------------------------------+---------------------------------------- > Reporter: dgregor | Owner: dgregor > Type: Bugs | Status: closed > Milestone: To Be Determined | Component: graph > Version: Boost Release Branch | Severity: Problem > Resolution: wontfix | Keywords: > -----------------------------------+---------------------------------------- > Changes (by jewillco): > > * status: reopened => closed > * resolution: => wontfix > > > Old description: > >> {{{ >> The graph adaptors (such as subgraph) do not support bundled >> properties, but they should. >> }}} > > New description: > > {{{ > The graph adaptors (such as subgraph) do not support bundled > properties, but they should. > }}} > > -- > > Comment: > > This is likely to work now, so closing as wontfix. Please reopen if the > problem still exists in the trunk version of Boost. > > -- > Ticket URL: <https://svn.boost.org/trac/boost/ticket/380#comment:7> > Boost C++ Libraries <http://www.boost.org/> > Boost provides free peer-reviewed portable C++ source libraries. > _______________________________________________ > Boost-bugs mailing list > Boost-bugs(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-bugs -- Marshall Marshall Clow Idio Software <mailto:mclow.lists@gmail.com> A.D. 1517: Martin Luther nails his 95 Theses to the church door and is promptly moderated down to (-1, Flamebait). -- Yu Suzuki

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DCVS vs CVS: call for constructivism
by Philippe Vaucher 28 Mar '12

28 Mar '12

Hello, I think we all know understood that there are people from both camps, some with emotional arguments, some with constructive arguments, but it's not really moving anywhere. We need to start listing what would have to be done and once we have such a map see if it's worth it before discussing pointless things. Just so we can redirect people saying things like "Nobody told me a real advantage yet" to this post, here's a recapitulation of what I think the advantages/disadvantages of a DCVS is ( http://www.ericsink.com/vcbe/html/dvcs_advantages.html, http://www.ericsink.com/vcbe/html/dvcs_weaknesses.html) Pro: - Offline work (you can use diffs, you can commit) - Speed of operations compared to svn - No need to setup a server to work locally (encourages participation (focus on working first, then sharing later)) Cons: - Cannot check out subpaths - Cannot lock files - Would require people to change their habits and learn new tools I think most people in the svn-camp will tell that with the 1.8 checkpoints feature you can now also commit while offline and thus the only advantages for DCVS seems to be speed and the ability to check all the data while offline. I think the people that are opposed to the change unfortunately won't be convinced by those arguments, even tho pretty much every who switched to DCVS will tell you that the advantages are worth it and it's more than simply speed or freedom, it's a philosophy etc. So I think the best thing to do now is first to make a map of what would have to be done if we decided to switch, to see if it's an option at all. Here's a simple draft, please participate into making it better: - Import current history - Migrate the existing hooks - Migrate the existing scripts around. - Migrate the test runners - Trac / Website integration (redmine with git extensions?) - Rights management (gitolite?) - Update release procedures Maybe we'd start a page on the wiki, but the idea is to find out if there are more steps to be done and if there's any showstopper in those steps. I think the best solution would be to offer the repository with several protocols, namely git/hg/svn so everyone could use the tool they want (e.g github offers svn/git, I know other hosts do it too). Philippe

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[Lockfree] Small compilation error with gcc -Wall
by Julien Nitard 28 Mar '12

28 Mar '12

Hi all, The following code seems to generate an "unused variable" variable warning with g++ -Wall. I am working on the latest version available from git, though I am not sure if this version is relevant. #include <boost/lockfree/fifo.hpp> typedef boost::lockfree::fifo<ReplicateData, boost::lockfree::static_freelist_t> Queue; Queue _buffer(4096); It occurs in fifo.hpp at line 263. Replacing tagged_node_ptr head2 = head_.load(memory_order_relaxed); By head_.load(memory_order_relaxed); Seems to do the job. Many thanks, Julien

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Boost Fusion suggestion
by Pavel Bažant 28 Mar '12

28 Mar '12

I am not actually a Boost developer, but have the following suggestion regarding boost.fusion: I find the macro BOOST_FUSION_DEFINE_STRUCT potentially very useful, but it does not provide means to influence the initialization list of the default constructor. Alternatively, means to emulate c++11 default initialization (the struct Foo {int x=10;} syntax) could be emulated. Such feature would be very useful, as it would minimize repetition and make it easier to ensure that uninitialized variables are nowhere used. I already generate my structs from BOOST_PP sequences in a similar way to BOOST_FUSION_DEFINE_STRUCT to avoid having to write json serialization boilerplate, but a variant of BOOST_FUSION_DEFINE_STRUCT i am suggesting would make this task even simpler. Pavel Bazant

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[functional] [overloaded_function] polymorphic functions?
by Lorenzo Caminiti 27 Mar '12

27 Mar '12

Hello all, I spent some time trying to make overloaded_function support polymorphic functions but I had little success :( 1) I was able to do this (see code below): overloaded_function< void (int) , functor<poly, void (generic)> > o(f, p); o(321); o(3.21); o("cba"); But I don't like it because I explicitly have to pass the functor type poly. I wanted instead to only use generic to tag the template parameters in the signature: overloaded_function< void (int) , void (generic) > o(f, p); o(321); o(3.21); o("cba"); I'd consider this acceptable but I wasn't able to program this because I loose p's type (poly) in base so base cannot hold a reference to the functor p... Is there a way around this? (Some type-erasure magic maybe??) 2) I don't think this can work with function templates because in order to get a pointer to a function template you have to instantiate it: g<char*> Now I can get the function pointer but it's not polymorphic anymore... 3) I don't think there is any way to implement make_overloaded_function with polymorphic types because I can't re-construct the function signature from the functor given that its operator contains template parameters... I have no idea on how to work around this... If you have suggestions for 1, 2, or 3), they are welcome. Otherwise, it seems that supporting polymorphic functions in overloaded_function is not really feasible... The little I got so far: #include <boost/function.hpp> #include <boost/type_traits/function_traits.hpp> #include <iostream> void f(int x) { std::cout << x << std::endl; } template<typename T> void g(T x) { std::cout << x << std::endl; } struct poly { template<typename T> void operator()(T x) { std::cout << x << std::endl; } }; template<typename F> struct base { template<typename G> base(G g) : f_(g) {} typename boost::function_traits<F>::result_type operator()( typename boost::function_traits<F>::arg1_type arg1 ) { return f_(arg1); } private: boost::function<F> f_; }; struct generic; template<typename Ftor, typename F> struct functor; template<typename Ftor, typename R> struct base< functor<Ftor, R (generic)> > { base(Ftor& ftor) : ftor_(ftor) {} template<typename Arg1> R operator()(Arg1 arg1) { return ftor_(arg1); } private: Ftor& ftor_; }; template<typename F1, typename F2> struct overloaded_function : base<F1>, base<F2> { template<typename G1, typename G2> overloaded_function(G1 g1, G2 g2) : base<F1>(g1), base<F2>(g2) {} using base<F1>::operator(); using base<F2>::operator(); }; int main() { f(123); g("xyz"); boost::function<void (char*)> gg = g<char*>; poly p; p(1.23); p("abc"); overloaded_function< void (int) , functor<poly, void (generic)> > o(f, p); o(321); o(3.21); o("cba"); return 0; } Thanks a lot. --Lorenzo

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[git] What's the IDE picture like?
by Rene Rivera 27 Mar '12

27 Mar '12

All this talk about switching to git brings up one important question for me, and I suspect others.. Given all the various git-flow, git-this, git-that, git-whatever, tools that are getting mentioned.. What is the process for a user that wants to do their development, including version control, like? Specifically what does an: * Eclipse user do? * Xcode user do? * VIsualStudio user do? I ask because I'm really tired of learning yet more command lines tools at this stage in my life. And even though all GUI tools have drawbacks they do have the advantage that they condense the workflow usages to something understandable. And I would be really hard pressed to use any new version control system that I can't use a GUI. And preferably an integrated GUI. -- -- -- Grafik - Don't Assume Anything -- Redshift Software, Inc. - http://redshift-software.com -- rrivera/acm.org - grafik/redshift-software.com -- 102708583/icq - grafikrobot/aim - grafikrobot/yahoo

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[move] explicit moving from a rvalue
by Vicente J. Botet Escriba 27 Mar '12

27 Mar '12

Hi Ion, With the current emulation of move semantics of Boost.Thread using Boost.move, I have a case that I would like to make working in a portable way boost::thread t = boost::thread( MoveOnly()); The library declares the template move constructor from a movable callable as as follows template <class F> explicit thread(boost::rv<F>& f); and MoveOnly is declared as defined below. The problem is a know limitation as the compiler is unable to deduce F as been MoveOnly even if MoveOnly is convertible to boost::rv<MoveOnly>& Jeffrey Lee Hellrung, Jr. made a proposal to try to solve the issue, but his proposal has a performance penality. Here it is a less elegant but efficient enough alternative. The addition of a explicit move conversion as ::boost::rv<MoveOnly>& move() { return *static_cast< ::boost::rv<MoveOnly>* >(this); } allows to the following to work as expected boost::thread t = boost::thread( MoveOnly().move()); While this workaround works when we are using the emulation it doesn't works when rvalue references are supported. I have defined a macro BOOST_EXPLICIT_MOVE that allows to write portable code #if ! defined BOOST_NO_RVALUE_REFERENCES #define BOOST_MOVE(RVALUE) RVALUE #else #define BOOST_MOVE(RVALUE) RVALUE.move() #endif that can be used as boost::thread t = boost::thread( BOOST_MOVE(MoveOnly())); The move() function is not really needed as the macro can hide the needed conversion, but could be preferred by users that don't need to make portable programs. The evident liability is of course the use of the macro. Is there something wrong on this design, something to to improve? The same design can be used on compilers, such as as SunStudio (see https://svn.boost.org/trac/boost/ticket/6222) that prefer the overload of a private copy constructor to an public move constructor. On these kind of compilers the following overload private: MoveOnly(MoveOnly&); public MoveOnly(boost::rv<MoveOnly>&) makes the following to fail at compile time MoveOnly MakeMoveOnly() { return MoveOnly(); } but MoveOnly( MakeMoveOnly(() { return BOOST_MOVE(MoveOnly()); } will work. Do you think that member functions as the explicit move() and a macro as BOOST_MOVE can be added to Boost.Move emulation? Best, Vicente ///////////////////////////// class MoveOnly { #ifndef BOOST_NO_DELETED_FUNCTIONS public: MoveOnly(const MoveOnly&)=delete; MoveOnly& operator=(MoveOnly const&); #else private: MoveOnly(MoveOnly&); MoveOnly& operator=(MoveOnly&); public: #endif MoveOnly() { } #ifndef BOOST_NO_RVALUE_REFERENCES MoveOnly(MoveOnly&&) {} #else #if defined BOOST_THREAD_USES_MOVE MoveOnly(boost::rv<MoveOnly>&) {} MoveOnly& operator=(boost::rv<MoveOnly>&) { return *this; } operator ::boost::rv<MoveOnly>&() { return *static_cast< ::boost::rv<MoveOnly>* >(this); } operator const ::boost::rv<MoveOnly>&() const { return *static_cast<const ::boost::rv<MoveOnly>* >(this); } ::boost::rv<MoveOnly>& move() { return *static_cast< ::boost::rv<MoveOnly>* >(this); } const ::boost::rv<MoveOnly>& move() const { return *static_cast<const ::boost::rv<MoveOnly>* >(this); } #else #error #endif #endif void operator()() { } };

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[quickbook] Controling the layout of table columns in docbook/fo output
by Andreas Pokorny 27 Mar '12

27 Mar '12

Hi, In an earlier thread I mentioned that I am using quickbook to write software design specification/documentation. The whole document grows nicely now. Since more people are contributing, I added howto chapters to the end of the document, including some kind of guided quickbook skeleton for new chapters and the quickbook documentation itself. The quickbook documentation creates warnings with fop: Mar 12, 2012 8:11:46 PM org.apache.fop.events.LoggingEventListener processEvent WARNING: table-layout="fixed" and column-width unspecified => falling back to proportional-column-width(1) (See position 1686:869) Mar 12, 2012 8:11:46 PM org.apache.fop.events.LoggingEventListener processEvent WARNING: table-layout="fixed" and column-width unspecified => falling back to proportional-column-width(1) (See position 1686:905) Mar 12, 2012 8:11:46 PM org.apache.fop.events.LoggingEventListener processEvent WARNING: table-layout="fixed" and column-width unspecified => falling back to proportional-column-width(1) (See position 1896:796) and more. That happens for every table. Inside the documentation about tables there one containing hello world source. There the proportional column width makes the source code leave the table and text area of the page. Is there a yet undocumented way to control column sizes? regards Andreas

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Re: [boost] [utility] Adding noexcept to boost::declval
by Michel Morin 27 Mar '12

27 Mar '12

Vicente J. Botet Escriba wrote >> Summary: >> Defining declval<T>() as add_lvalue_reference<T>::type is wrong; >> add_lvalue_reference should be removed! >> >> > There is something that disturb me by returning just T, doesn't this forces > the type T to CopyConstructible? Nope. T needs not to be CopyConstructible (Note that declval can be used only in unevaluated contexts.) > The idea to use T& instead was to avoid > this. You shouldn't do this, because this transforms rvalues to lvalues. > I have rolled back at revision 77562. Thanks, Vicente! Minor issue: `#include <boost/type_traits/add_lvalue_reference.hpp>` is not removed yet. Regards, Michel

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