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Re: [boost] [GIL] scoped_channel_value type
by fabien.castan＠free.fr 22 Jul '10

22 Jul '10

>> So if you want to extract this, you will have to special-case >> scoped_channel_value anyway. So in this case you don't need a typedef >> inside. >> You can just define a specialization like this: >> >> Template <typename ChannelValue> >> Struct base_channel_value { >> typedef ChannelValue type; >> }; >> >> Template <typename ChannelValue, typename MinV, typename MaxV> >> Struct base_channel_value<scoped_channel_value<ChannelValue, MinV, MaxV> > >> { >> typedef ChannelValue type; >> }; >> > >I really have to write that one down. I keep on forgetting this trick. Thanks ! Maybe this utility structure can be added (like channel_type, etc.) ?

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[GIL] scoped_channel_value type
by fabien.castan＠free.fr 22 Jul '10

22 Jul '10

Hi, I would like to get the value type of the channels depending on an image view. So I can get the scoped channel type, from MyView type, like this: typedef typename boost::gil::channel_type<MyView>::type MyScopedChannel; But I can't get the primitive type used by the scoped channel. For example, if the type is scoped_channel_value<float,float_zero,float_one>, I can't get the float type. /// \ingroup ScopedChannelValue /// \brief A channel adaptor that modifies the range of the source channel. Models: ChannelValueConcept template <typename BaseChannelValue, // base channel (models ChannelValueConcept) typename MinVal, typename MaxVal> // classes with a static apply() function returning the minimum/maximum channel values struct scoped_channel_value { typedef BaseChannelValue base_channel_t; //< missing typedef //... } So this will allows to use: typedef typename boost::gil::channel_type<MyView>::type::base_channel_t ChannelBaseType; Are you agree to add this typedef ? Best regards, Fabien Castan

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fixed size vector in boost::numeric::ublas?
by Markus Grabner 22 Jul '10

22 Jul '10

Hi all! In boost::numeric::ublas, there exist different vector variants (unbounded and bounded). All of them can be resized dynamically (up to a maximum size defined at compile time in the case of the bounded vector). Therefore the vector class (or the underlying storage array) have a size member which indicates the current size of the vector. However, it would be extremely useful to have a vector of fixed size, i.e., one which can't be resized dynamically, but has its size statically defined at compile time. Such a vector does not require a size member and only consumes N*sizeof(T) bytes of storage, where N is the (static) vector size and T the value type. Many libraries dealing with geometric data (OpenGL and OpenInventor being prominent examples) store their data in compact arrays in their native data types, e.g., the values (x0,y0,z0,x1,y1,z1,x2,y2,z2) stored in consecutive memory locations define three points in 3D space. By means of a fixed size vector, the entire boost::numeric::ublas functionality could be applied to such arrays by a simple reinterpret_cast on each element. This is not possible with the bounded or unbounded vectors since the vector must be constructed before with its size member properly initialized, and the actual vector data must therefore be copied explicitly before use. I tried to create a fixed_array class to implement this proposal (see attachment), it can be used, e.g., to create the equivalent of the OpenInventor "SbVec3f" data type as follows: typedef boost::numeric::ublas::vector<float,fixed_array<float,3> > vec3d_t; It is probably not the cleanest solution, and I skipped the serialization stuff altogether, but it demonstrates an approach how this can be done. What do you think about adding such an extension to improve boost's interoperability with other libraries? Thanks & kind regards, Markus -- Markus Grabner Institute for Computer Graphics and Vision Graz University of Technology, Inffeldgasse 16a/II, 8010 Graz, Austria WWW: http://www.icg.tugraz.at/Members/grabner

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[ref] incompatibility with c++0x
by Andy Venikov 21 Jul '10

21 Jul '10

The latest c++0x FCD defines the single argument constructor for reference_wrapper(T &) as non-explicit. The boost version is explicit. Was it done on purpose? Should it be changed to non-explicit? BTW, I think original standard drafts did have it as explicit since gcc 4.3.3 still defines it as explicit. But in the final draft (as in gcc 4.5) it's non-explicit. I know that boost::reference_wrapper is not the same as std::reference_wrapper, but still it would be nice to have some uniformity. Thanks, Andy.

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info about boost process
by Conoscenza Silente 21 Jul '10

21 Jul '10

Hi All Do you know whether "boost.process" will become part of the boost library at some point? I need some C++ way to start-stop processes and getting the console output produced by them and it seems that this library is doing right that. I see it in the BOOST VAULT that the development is stopped since 2008. Do you know what are the plans for it and if there is some alternative I can use in current/future boost library? Thanks AFG

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[Graph] Problems customizing edge storage for adjacency_list
by Alex Betts 21 Jul '10

21 Jul '10

Hello! I can't seem to use a custom container for storing edge data when using adjacency_list (this is with gcc 4.1.0 on Linux, but it won't work for gcc 4.3.0 either). I understand that I need to create push() and erase() functions for the custom container, but the compiler never seems to see my implementations of these two functions, as it always gives an error like: boost/pending/container_traits.hpp:414: error: no matching function for call to ‘container_category(...)’ ...from the default implementation of push() defined in container_traits.hpp. I've tried moving push() and erase() in and out of the boost::graph_detail namespace, but that doesn't seem to help. I've attached the source for the program in question, & appreciate any help! thanks, -- Alex

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boost graph.
by Giorgio Zoppi 21 Jul '10

21 Jul '10

Hi, I've a problem with multiple links on the same vertexes. For example we've vertex A and vertex B and we want identify two different edges that they connects to these edges, i.e. A-->B with cost 6 A-->B with cost 8 Is there any way to tag or label these links and using the dijkstra algorithm on the graph? Cheers, Giorgio. -- Quiero ser el rayo de sol que cada día te despierta para hacerte respirar y vivir en me. "Favola -Moda".

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[Serialization & Archive ]
by Alapkumar Sinha 21 Jul '10

21 Jul '10

Hi, Can someone tell me what is the difference between the Archive & Serialization library and what are the scenarios in which one has to chose one over the other? Regards, Alap ________________________________ This Email may contain confidential or privileged information for the intended recipient (s) If you are not the intended recipient, please do not use or disseminate the information, notify the sender and delete it from your system. ______________________________________________________________________

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Is there any compile time/static rational numbers library in BOOST ?
by Reetesh Mukul 21 Jul '10

21 Jul '10

Hi, Is there any compile time/static rational numbers library in BOOST ? I can see that static GCD/LCM libraries are there, but could not find it for static rationals. Another question, is there any compile time library which calculates ceil value of division of one integer by another one ? With Regards, Reetesh Mukul

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First set of Boostcon 2010 videos are available
by Marshall Clow 21 Jul '10

21 Jul '10

Almost all of the Transactional Memory sessions from Boostcon are now available, with the exception of Tatiana Shpeisman's presentation on the "Draft Specification of Transactional Language Constructs for C++". That talk should (hopefully) be available tomorrow. Here are the links Maurice Herlihy : Transactional Memory Today - Keynote: http://blip.tv/file/3900047/ Justin Gottschlich:TBoost.STM Engine: http://blip.tv/file/3900167/ Tatiana Shpeisman: Draft Specification of Transactional Language Constructs for C++: <coming soon> Michael Wong: IBM's TM Research: http://blip.tv/file/3900242/ Mark Moir: Sun's / Oracle's TM Research: http://blip.tv/file/3905166/ Tatiana Shpeisman: Intel's TM Research: http://blip.tv/file/3905189/ Hartmut - I apologize for removing your (very nice) introduction for Maurice from the video. Unfortunately, Maurice was wearing the microphone, and none of what you said could be heard. -- Marshall

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