June 2007 - Boost - lists.boost.org

Improving Boost Docs Project, WikiPage
by Matias Capeletto 20 Jul '07

20 Jul '07

Hi, I have added a new page to boost wiki so we can coordinate our efforts: http://svn.boost.org/trac/boost/wiki/ImprovingBoostDocs * If you want to help us, please jump in. * If you are an author of a lib with html based docs and want to authorize us to help you to translate your docs, please scream it here. * If you are an author of a lib with boostbook based docs and want to authorize us to help you to translate your docs, please state it here. Best regards Matias

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[extension]
by Stephan Diederich 16 Jul '07

16 Jul '07

Hi, I've some questions regarding boost.extension which I think is currently prepared to review by Mariano Gabriel Consoni as one of the SoC Projects. We want to use a plugin loading mechanism in one of our projects and have some ideas currently not included in the boost.extensions library. - Some kind of versioning of interfaces and implementations. The idea is to give an interface (whose implementation is loaded as an extension) a version, which can be later compared to the version of the loaded implementation. As one of boost.extension's goal is NOT to modify a class-header to make it loadable, this should possibly be an optional feature. Another option would be to give non versioned interfaces always version 0 or 1. - It would be nice, if the plugin-loader provides functionality to "switch" the interface of an instance of an implementation. IIRC, the zone object knows, which interfaces are implemented by a loadable class. (when the dll is loaded, the export-function registers all the possible interfaces of one class to the zone). With that information it should be possible to determine if a given instance of a loaded class can be casted to another interface. (I think that casting has to be done in the loaded extension, as this is the only place where the layout it known. ) Are there any plans to include above mentioned functionality in boost.extension? Thanks in advance, Stephan

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Interest in tensor library?
by Jeremy Bruestle 14 Jul '07

14 Jul '07

Greetings, I have developed a C++ tensor library using template expressions which allows Einstein summation convention to be used to describe mathematical operations on tensors in C++. This allows a great simplification in syntax, while retaining execution speeds identical to hand optimized C code in most cases. An example of the syntax is: // Declare three rank 2 tensors (rank = # of dimensions) of doubles with sizes of // 6 x 5, 6 x 10, and 10 x 5 respectively tensor<double, 2> A(6, 5); tensor<double, 2> B(6, 10); tensor<double, 2> C(10, 5); // Name three index variable to be used in what follows index_variable<0> i; index_variable<1> j; index_variable<2> k; A[i][j] = 1.0; // Initialize A to all 1's B[i][j] = 4.5; // Initalize B to all 4.5 boost::mt19937 rng; C[i][j] = trand(rng); // Initalize C to uniform random numbers 0-1 C[i][2] = 2.1; // Set row 2 to 2.1 C[2][i] = 5.5; // Set col 2 to 5.5 C[2][2] = 0.0; // Zero out 2,2 A[i][j] = B[i][k] * C[k][j]; // Perform a matrix multiply /* The above line translates roughly as: for(size_t i = 0; i < A.size<0>(); i++) { for(size_t j = 0; j < A.size<1>(); j++) { double total = 0.0; for(size_t k = 0; k < B.size<1>(); k++) total += B[i][k] * C[k][j]; A[i][j] = total; } } */ An unlimited number of dimensions are supported, arbitrary operations are allowed, and for cases where you wish to perform other types of cumulative functions, such as finding the maximum element, a syntax such as: A[i] = max(j, B[i][j]); is allowed. There are lots of other interesting features but I don't wish to make this email too long. As far as efficency, Intel's compiler builds every example I've tried so far into code as good as doing the work by hand. GCC does so for expressions of reasonably complexity, and MSVC's optimizer does alright, but not nearly as well as the others. I was interested in knowing what the interest level of providing such a library as part of boost would be. I've tried to adhere to the boost coding guidelines during the construction. I've been using this library for over 6 months myself for scientific computing. However, I've so far avoiding sending a query to the boost mailing lists as the procedures for submission and review seem quite daunting. I'm usually crushingly busy, and I'm also especially bad at documentation. Still, I thought I would float the idea to guage interest, and also ask if anyone would be interested in helping me through the process somewhat. Thank you for you time. -Jeremy Bruestle

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[rfc] I/O Library Design
by Sebastian Redl 11 Jul '07

11 Jul '07

Hi, A few weeks ago, a discussion that followed the demonstration of the binary_iostream library made me think about the standard C++ I/O and what I would expect from an I/O model. Now I have a preliminary design document ready and would like to have some feedback from the Boost community on it. The document can be found here: http://windmuehlgasse.getdesigned.at/newio/ I'd especially like input on the unresolved issues, but all comments are welcome, even if you tell me that what I'm doing is completely pointless and misguided. (At least I'd know not to waste my time with refining and implementing the design. :-)) Sebastian Redl

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Re: [boost] [Fusion] Notice of breaking change
by dan marsden 09 Jul '07

09 Jul '07

>The definition of Fusion polymorphic function object will be changed shortly to be consistent with boost.resultof. Instead of requiring a nested result metafunction of the form: > >template<typename T0, typename T1, ... typename TN> >struct result >{ > typedef xxx type; >}; > >A polymorphic function object will instead simply be required to suppport > >boost::result_of<F(A,B,...Z)>::type > >as a valid expression. > >This will break some Fusion client code, specifically, if you are using >fold, accumulate, transform, or a lot of the components in the functional section >of the library, you may need to make changes to support this change. > >The change should be entered into CVS head over the forthcoming weekend. The above change has now been applied. Docs upgrades will follow in the next few days. Thanks Dan ___________________________________________________________ What kind of emailer are you? Find out today - get a free analysis of your email personality. Take the quiz at the Yahoo! Mail Championship. http://uk.rd.yahoo.com/evt=44106/*http://mail.yahoo.net/uk

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BoostCon Trip Report online at The C++ Source
by Eric Niebler 08 Jul '07

08 Jul '07

My impressions of the first annual Boost Conference are now online at The C++ Source for your reading pleasure. Enjoy! http://www.artima.com/cppsource/boost_con_07.html -- Eric Niebler Boost Consulting www.boost-consulting.com The Astoria Seminar ==> http://www.astoriaseminar.com

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Review Request: Boost Exception
by Emil Dotchevski 08 Jul '07

08 Jul '07

I believe the proposed Boost Exception library is now mature enough for formal review. Please read the documentation at: http://www.revergestudios.com/boost-exception/boost-exception.htm Here is a direct link to the source code, boost build jamfiles and tests. Tested with MSVC 7.1, MSVC 8.0, GCC 3.4.4, and Comeau C++ 4.3.8: http://www.revergestudios.com/boost-exception/boost-exception.zip Regards, Emil Dotchevski

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[fusion] Illegal partial specialization error.
by Michael Marcin 07 Jul '07

07 Jul '07

If I include <boost/fusion/support/tag_of.hpp> my compiler (derived from Metrowerks 9.4) gives me several errors claiming illegal partial specializations. It looks like it's partially specializing forward declarations of the tag_of structure. I don't know if that's allowed (from the error I assume probably not) but it certainly seems to be pointless to me. Are these perhaps supposed to be more than declarations? Thanks, Michael Marcin

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Interest in a static-sized version of cvalarray
by Michael Tegtmeyer 07 Jul '07

07 Jul '07

Some time ago I posted a message to this list about interest in a static-sized version of cvalarray. I'll include the original message for reference. I received some emails stating that there was interest. The implementation has been in the sandbox for some time now. I'd like to guage interest again to determine if it is worth working to add to boost. The implementation has not been boostified because it is in active use here where I work (autotool land) so if there is interest, some additional work needs to be done to absorb the boost framework. The implementation is complete without any known bugs. There is only one header but you can go though the normal ./configure, make, make install to put it somewhere. Tests can be run using 'make check' and documentation is in the doc directory. Of additional interest since my previous post: the implementation will now automaticallty unroll all numeric ops at compile time (subject to the compiler) up to a predefined array size. My original post: Hello, I am trying to guage interest in a fixed sized version of valarray. I frequently found myself using small(-ish) compile-time known sized numeric arrays that don't justify the overhead of operator new in std::valarray but needed the math interface that valarray provided. I wrote a static-sized version of valarray for this purpose. It is modeled after std::valarray and implements about 90% of valarray's interface (obviously resizing is not included, neither is gslice due to the result not being known at compile time). Examples of it's use are: float _v[10] = {...}; size_t _i[5] = {...}; cvalarray<float,10> v1(_v); cvalarray<float,5> v2 = v1[cslice<0,5,2>()]; v1[cslice<0,3,3>()] = 0.0f; cvalarray<size_t,5> ind(_i); cvalarray<float,5> cvalB = v1[ind]; v2 *= (v2 + v1) / 2.0; //all of the usual math ops I have a complete implementation that models std::valarray in every possible way (with compile-time known limitations) including expression-template support for the numeric ops. My testing indicates a decent performance increase over gcc4's valarray for small number of elements <1000. If anyone has any interest, I'll put together some docs and throw it in the sandbox. Mike Tegtmeyer

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[BGL] Adapter from bidirectional to undirected graph
by Benoit 05 Jul '07

05 Jul '07

Hello everyone, I have been using the BGL for quite some time with both directed and bidirectional graphs (with adjacency_list). Sometimes i need to use these graphs in algorithms as if they were undirected... AFAICT, this is currently not possible because out_edges() exists in all cases, but don't do the same... The obvious solution consists in writing a dedicated adapter used for translating a bidirectional graph into a directed one at least for out_edges(), and optionally for other stuff (internal properties, vertex and edge descriptors?) to make this subtle change as transparent as possible. Can you think of another way ? Is there already such an adapter somewhere (i have unsuccessfully tried to find one...) ? In case it didn't exist, would anyone else be interested to have one ? Benoît PS : I'd like to thank the authors of the BGL, it's a pleasure to work with it everyday !

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