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Re: [Boost-users] variant over base and derived classes
by Hicham Mouline 09 Dec '10

09 Dec '10

>> -----Original Message----- >> From: Hicham Mouline [mailto:hicham@mouline.org] >> Sent: 09 December 2010 00:04 >> To: 'boost-users(a)lists.boost.org' >> Subject: variant over base and derived classes >> >> hello, >> >> How to determine the actual type of the object stored in a variant? >> >> struct S { >> virtual ~S() >> {} >> }; >> >> struct Deriv1 : public S { >> virtual ~Deriv1() >> {} >> }; >> >> struct Deriv2 : public S { >> virtual ~Deriv2() >> {} >> }; >> >> struct Deriv3 : public Deriv2 { >> virtual ~Deriv3() >> {} >> }; >> >> typedef boost::variant<S,Deriv1, Deriv2, Deriv3> my_variant_t; >> >> Deriv3 d3; >> >> struct print_type: public boost::static_visitor<> { >> template <typename T> >> void operator()(const T&) const >> { >> std::cout<< typeid(T).name() <<std::endl; >> } >> }; >> >> const S& s = d3; >> my_variant_t v = s; >> boost::apply_visitor( print_type(), v ); >> >> This prints S. >> >> Is it a truncated copy of d3 that is stored v? >Yes. >> How do I construct v polymorphically so that the real object is stored? >> >> regards, >You have to downcast before creating the variant. >boost::variant only uses the static type of the object. >In Christ, >Steven Watanabe If I am given a const S* sptr, how do I construct an instance of the above variant then? const Deriv1* d1ptr; const Deriv2* d2ptr; const Deriv3* d3ptr; my_variant_t v = ((d1ptr = dynamic_cast<const Deriv1*>(sptr)) != 0 )? *d1ptr: ((d2ptr = dynamic_cast<const Deriv2*>(sptr)) != 0 )? *d2ptr: ((d3ptr = dynamic_cast<const Deriv3*>(sptr)) != 0 )? *d3ptr: *sptr; Is there a better way of writing this? rds,

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emacs mode for quickbook?
by Wilhelm 09 Dec '10

09 Dec '10

Hi, does anybody know of there is already an emacs-mode for quickbook? -- Wilhelm

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[Proto] Failed to Mimic the "Lazy Vector" Example
by Hossein Haeri 08 Dec '10

08 Dec '10

Dear all, Trying to mimic what comes in the Lazy Vector example http://www.boost.org/doc/libs/1_45_0/doc/html/proto/users_guide.html#boost_… I get a strange error speaking about result_of and the like. My guess is that there is some specialisation of a function object which does do the job for std::vector<> that I need to also specialise for my class. I can't find any track of that thing though. And, I might be totally wrong too... Anyway, for your reference, I have put the code as well as the error message that I get in GCC 4.5.1, MinGW, WinXP, SP3 in the PS section of this posting. Any ideas please? TIA,--Hossein <Code> #include <iostream> #include <boost/proto/proto.hpp> namespace mpl = boost::mpl; namespace proto = boost::proto; using proto::_; struct EWBase {}; typedef proto::terminal<double (*) (double)> FunctionType; struct EmtGrammar: proto::or_ < proto::terminal<EWBase>, proto::shift_right<EmtGrammar, FunctionType> > {}; struct EmtDomain; template<typename Expr> struct EmtExpr : proto::extends<Expr, EmtExpr<Expr>, EmtDomain> { typedef proto::extends<Expr, EmtExpr<Expr>, EmtDomain> base_type; EmtExpr( Expr const & expr = Expr() ) : base_type( expr ) {} }; template< typename T > struct Emt : EmtExpr<typename proto::terminal<EWBase>::type> { typedef typename proto::terminal<EWBase>::type expr_type; Emt(): EmtExpr<expr_type>(expr_type::make(EWBase())) {} }; struct EmtDomain : proto::domain<proto::generator<EmtExpr>, EmtGrammar> {}; int main() { return 0; } </Code> <Error Message> -------------- Build: Debug in ProtoGame2 --------------- Compiling: main.cpp In file included from D:\Sources\Boost\boost_1_42_0/boost/proto/traits.hpp:34:0, from D:\Sources\Boost\boost_1_42_0/boost/proto/expr.hpp:27, from D:\Sources\Boost\boost_1_42_0/boost/proto/core.hpp:17, from D:\Sources\Boost\boost_1_42_0/boost/proto/proto.hpp:12, from D:\My Documents\My Programmes\Tutorial\Proto\ProtoGame2\main.cpp:3: D:\Sources\Boost\boost_1_42_0/boost/utility/result_of.hpp: In instantiation of 'boost::detail::result_of_nested_result<EmtDomain, EmtDomain(boost::proto::exprns_::expr<boost::proto::tag::function, boost::proto::argsns_::list1<const EmtExpr<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<EWBase>, 0l> >&>, 1l>)>': D:\Sources\Boost\boost_1_42_0/boost/utility/result_of.hpp:75:1: instantiated from 'boost::detail::result_of_impl<EmtDomain, EmtDomain(boost::proto::exprns_::expr<boost::proto::tag::function, boost::proto::argsns_::list1<const EmtExpr<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<EWBase>, 0l> >&>, 1l>), false>' D:\Sources\Boost\boost_1_42_0/boost/utility/detail/result_of_iterate.hpp:24:109: instantiated from 'boost::result_of<EmtDomain(boost::proto::exprns_::expr<boost::proto::tag::function, boost::proto::argsns_::list1<const EmtExpr<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<EWBase>, 0l> >&>, 1l>)>' D:\Sources\Boost\boost_1_42_0/boost/preprocessor/iteration/detail/local.hpp:34:1: instantiated from 'boost::proto::exprns_::extends<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<EWBase>, 0l>, EmtExpr<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<EWBase>, 0l> >, EmtDomain, 0l>' D:\My Documents\My Programmes\Tutorial\Proto\ProtoGame2\main.cpp:25:1: instantiated from 'EmtExpr<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<EWBase>, 0l> >' D:\My Documents\My Programmes\Tutorial\Proto\ProtoGame2\main.cpp:36:1: instantiated from here D:\Sources\Boost\boost_1_42_0/boost/utility/result_of.hpp:68:1: error: invalid use of incomplete type 'struct EmtDomain' D:\My Documents\My Programmes\Tutorial\Proto\ProtoGame2\main.cpp:20:8: error: forward declaration of 'struct EmtDomain' In file included from D:\Sources\Boost\boost_1_42_0/boost/proto/extends.hpp:533:0, from D:\Sources\Boost\boost_1_42_0/boost/proto/core.hpp:23, from D:\Sources\Boost\boost_1_42_0/boost/proto/proto.hpp:12, from D:\My Documents\My Programmes\Tutorial\Proto\ProtoGame2\main.cpp:3: D:\Sources\Boost\boost_1_42_0/boost/preprocessor/iteration/detail/local.hpp: In instantiation of 'boost::proto::exprns_::extends<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<EWBase>, 0l>, EmtExpr<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<EWBase>, 0l> >, EmtDomain, 0l>': D:\My Documents\My Programmes\Tutorial\Proto\ProtoGame2\main.cpp:25:1: instantiated from 'EmtExpr<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<EWBase>, 0l> >' D:\My Documents\My Programmes\Tutorial\Proto\ProtoGame2\main.cpp:36:1: instantiated from here D:\Sources\Boost\boost_1_42_0/boost/preprocessor/iteration/detail/local.hpp:34:1: error: no type named 'type' in 'struct boost::result_of<EmtDomain(boost::proto::exprns_::expr<boost::proto::tag::function, boost::proto::argsns_::list1<const EmtExpr<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<EWBase>, 0l> >&>, 1l>)>' In file included from D:\Sources\Boost\boost_1_42_0/boost/proto/traits.hpp:34:0, from D:\Sources\Boost\boost_1_42_0/boost/proto/expr.hpp:27, from D:\Sources\Boost\boost_1_42_0/boost/proto/core.hpp:17, from D:\Sources\Boost\boost_1_42_0/boost/proto/proto.hpp:12, from D:\My Documents\My Programmes\Tutorial\Proto\ProtoGame2\main.cpp:3: D:\Sources\Boost\boost_1_42_0/boost/utility/result_of.hpp: In instantiation of 'boost::detail::result_of_nested_result<EmtDomain, EmtDomain(boost::proto::exprns_::expr<boost::proto::tag::function, boost::proto::argsns_::list1<EmtExpr<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<EWBase>, 0l> >&>, 1l>)>': D:\Sources\Boost\boost_1_42_0/boost/utility/result_of.hpp:75:1: instantiated from 'boost::detail::result_of_impl<EmtDomain, EmtDomain(boost::proto::exprns_::expr<boost::proto::tag::function, boost::proto::argsns_::list1<EmtExpr<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<EWBase>, 0l> >&>, 1l>), false>' D:\Sources\Boost\boost_1_42_0/boost/utility/detail/result_of_iterate.hpp:24:109: instantiated from 'boost::result_of<EmtDomain(boost::proto::exprns_::expr<boost::proto::tag::function, boost::proto::argsns_::list1<EmtExpr<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<EWBase>, 0l> >&>, 1l>)>' D:\Sources\Boost\boost_1_42_0/boost/preprocessor/iteration/detail/local.hpp:34:1: instantiated from 'boost::proto::exprns_::extends<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<EWBase>, 0l>, EmtExpr<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<EWBase>, 0l> >, EmtDomain, 0l>' D:\My Documents\My Programmes\Tutorial\Proto\ProtoGame2\main.cpp:25:1: instantiated from 'EmtExpr<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<EWBase>, 0l> >' D:\My Documents\My Programmes\Tutorial\Proto\ProtoGame2\main.cpp:36:1: instantiated from here D:\Sources\Boost\boost_1_42_0/boost/utility/result_of.hpp:68:1: error: invalid use of incomplete type 'struct EmtDomain' D:\My Documents\My Programmes\Tutorial\Proto\ProtoGame2\main.cpp:20:8: error: forward declaration of 'struct EmtDomain' In file included from D:\Sources\Boost\boost_1_42_0/boost/proto/extends.hpp:533:0, from D:\Sources\Boost\boost_1_42_0/boost/proto/core.hpp:23, from D:\Sources\Boost\boost_1_42_0/boost/proto/proto.hpp:12, from D:\My Documents\My Programmes\Tutorial\Proto\ProtoGame2\main.cpp:3: D:\Sources\Boost\boost_1_42_0/boost/preprocessor/iteration/detail/local.hpp: In instantiation of 'boost::proto::exprns_::extends<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<EWBase>, 0l>, EmtExpr<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<EWBase>, 0l> >, EmtDomain, 0l>': D:\My Documents\My Programmes\Tutorial\Proto\ProtoGame2\main.cpp:25:1: instantiated from 'EmtExpr<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<EWBase>, 0l> >' D:\My Documents\My Programmes\Tutorial\Proto\ProtoGame2\main.cpp:36:1: instantiated from here D:\Sources\Boost\boost_1_42_0/boost/preprocessor/iteration/detail/local.hpp:34:1: error: no type named 'type' in 'struct boost::result_of<EmtDomain(boost::proto::exprns_::expr<boost::proto::tag::function, boost::proto::argsns_::list1<EmtExpr<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<EWBase>, 0l> >&>, 1l>)>' Process terminated with status 1 (0 minutes, 2 seconds) 6 errors, 0 warnings </Error Message>

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Re: [Boost-users] mpi: sending/receiving different types
by Hicham Mouline 08 Dec '10

08 Dec '10

-----Original Message----- From: "Riccardo Murri" [riccardo.murri(a)gmail.com] Date: 08/12/2010 01:50 PM To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] mpi: sending/receiving different types >> 2. the root sends directly a reference to a base class of anything sendable, >> then the receivers construct the derived classes on reception with >> broadcast. The T is then the base class type. >> > There's a risk of slicing here, i.e., if you pass a reference to a > base class, only the base class data will be serialized and received. > As far as I understand, Boost.Serialization (hence Boost.MPI) will do > the correct thing if you use *pointers* instead: i.e., you send a > pointer to a (derived) class and you receive it through a pointer to > the base class. > (Beware: I have not checked!) Does Boost.Serialization/MPI construct an object on the heap when it deserializes? e.g. master: base* b = &derived; broadcast( world, b, 0 ); slave: base* b; broadcast( world, b, 0 ); /// does this create the appropriate derived class on the heap, and make b point to it? Is this what you meant? Another question, the base struct contains a double and 2 char[8] fields, but also a virtual function. Does this mean it shouldn't be set as being a MPI data type because of its polymorphism? Thanks,

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[Serialization] Inconsistent tracking_level when switching from static to DLL
by Guy Prémont 08 Dec '10

08 Dec '10

Hi, I am using boost (1.40) serialization on Windows (VS 2008) to serialize a complex hierarchy of classes. My application is composed of different modules, each having its own serialization library. I have a Core library, with a CoreSerialization library, that defines a bunch of classes and base data types; I also have a Vehicle library, with a separate VehicleSerialization library, the defines some other classes with base classes in Core and that also use some user data types defined in Core. Using static libraries, everything saves and loads perfectly. We recently switched to using DLLs. When loading and saving with an application that only uses core (as Dlls) everything serializes perfectly. We can load files that were generated by an older application (using static libraries), save them and load them back. If the application also uses the Vehicle libraries, it can load older files (generated using static libraries), save them, but fails to load them back. The difference between the files generated with a DLL application and a static link application, lies in the tracking of certain classes. Since the serialization is split between 2 DLLs, the tracking level (by default selectively) will actually depends on what classes are serialized in the DLL and may be different in different DLLs. This seems to be cause by the various singleton that are created, notably pointer_oserializer<T> and oserializer<T>. In a statically linked application, there is only one instance on those singleton, in a DLL linked application, there is one instance of the singleton for each DLL. I've also noticed that in my Core DLL, for certain type, there are both notably pointer_oserializer<T> and oserializer<T>, while in the Vehicle DLL, there is only notably oserializer<T>, hence the difference in tracking level. There is an easy fix here, not to use selective tracking but track always or never, explicitly. But still, there seems to be some data that needs to be shared across various serialization DLLs. I am a bit worry about some other bugs popping out relative to it. Has this bug ever been found? It may be a side effect of putting serialization code in DLLs, the documentation on that subject is a bit sparse. Thanks for any inputs Guy -- Guy Prémont, D.Sc. Architecte logiciel senior / Senior software architect CM Labs Simulations Inc. <blocked::http://www.cm-labs.com/> http://www.cm-labs.com/ Tel. 514-287-1166 ext. 237

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Re: [Boost-users] [gil] Using gil::color_converted_view with gil::for_each_pixel (Christian Henning)
by Chris Yuen 08 Dec '10

08 Dec '10

Dear Christian, > > > > 2. This compiles > > > > gil::gil_function_requires<gil::ImageViewConcept<int> >(); > What do you mean? This shouldn't compile? I was under the impression that the point of gil_function_requires is to do static checking to ensure that a type is compatible with an GIL type? (Something akin to BOOST_CONCEPT_ASSERT) Is an int supposed to be compatible with ImageViewConcept? From the GIL tutorial http://stlab.adobe.com/gil/html/giltutorial.html#GenericVersionSec, it seems like it's being used as a static type check, and int clearly isn't compatible to an image view. Am I missing something? Best regards, Chris Yuen

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[DateTime] overflow in posix_time::microseconds
by gast128 08 Dec '10

08 Dec '10

Hello all, we encountered an overflow in posix_time::microseconds: //about 40 years (1970-2010) const __int64 n = 1267195987000000; boost::posix_time::microseconds td(n); //overflow The overflow is easy explainable since date_time::subsecond_duration first multiplies it causing the overflow and then divides by 1000000. There are already multiple posts spended on this, but I saw no definitive answer. Can someone help? Alternatively we could work around it by first divide the hour part out of it (which makes the number smaller) before adding to a ptime, but preferably we would like this to see solved in the library itself.

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Re: [Boost-users] mpi non-blocking communication
by Hicham Mouline 08 Dec '10

08 Dec '10

> (1) You must initialize MPI with MPI_Init_thread() instead of >MPI_Init(). The boost::mpi::communicator ctor uses MPI_Init(), so you >must run the initialization yourself and *then* create the >communicator object. For instance:: > MPI_Init_thread(&argc, &argv, MPI_THREAD_SERIALIZED) > // ... > mpi::communicator world; Riccardo, I have the following code in my main: int main(int argc, char* argv[]) { boost::mpi::environment env(argc, argv); const int mpi_thread_support = MPI::Init_thread(argc, argv, MPI_THREAD_SERIALIZED ); if (mpi_thread_support != MPI_THREAD_SERIALIZED) { std::cerr<< "MPI implementation does not support threads" <<std::endl; return 1; } boost::mpi::communicator world; ... } This prints an error however: Calling MPI_Init or MPI_Init_thread twice is erroneous. How does 1 avoid that the mpi::communicator constructor calling MPI_INIT twice? Perhaps it's the environment constructor that calls MPI_INIT? rds,

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error when compiling boost 1.45
by Sean Farrow 08 Dec '10

08 Dec '10

Hi: I'[m trying to compile boost 1.45, with zlib/bzip2 support in the io streams library. My command line is: bjam toolset=msvc --stagedir=stage/vc/v10/32-bit -sZLIB_SOURCE="c:\progra~1\zlib" -sBZIP2_SOURCE="c:\progra~1\bzip2" --build-type=complete >boost.txt I get the following warning: LINK : fatal error LNK1181: cannot open input file 'boost_zlib.lib' This command line worked for compiling 1.44. Anyone got any ideas? Cheers Sean.

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Re: [Boost-users] Code stopped compile after migrating 1.42->1.45 (worked around)
by Pavel Pervov 08 Dec '10

08 Dec '10

I've worked it around with the specialisation boost::lambda::bind<int> for now and filed a ticket #4962 (https://svn.boost.org/trac/boost/ticket/4962) WBR, Pavel. --- This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and delete this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden. Please refer to http://www.db.com/en/content/eu_disclosures.htm for additional EU corporate and regulatory disclosures.

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