- Boost - lists.boost.org

[type_traits] warning free is_signed on g++
by Edd Dawson 18 Sep '09

18 Sep '09

Hello, When using boost::is_signed<> on types such as unsigned int and unsigned long, various recent versions of g++ (MinGW 4.4.0 and Apple's 4.0.1, at least) spit out a warning: warning: comparison of unsigned expression < 0 is always false Would there be any harm in changing boost::detail::is_signed_helper in boost/type_traits/is_signed.hpp as follows? template <class T> struct is_signed_helper { typedef typename remove_cv<T>::type no_cv_t; // BOOST_STATIC_CONSTANT(bool, value = (static_cast<no_cv_t>(-1) < 0)); BOOST_STATIC_CONSTANT(bool, value = (static_cast<no_cv_t>(-1) < 1)); }; This change gets rid of the warnings emitted by g++. Kind regards, Edd

3 2

Boost on MSVC without Microsoft Extensions
by Craig Henderson 17 Sep '09

17 Sep '09

I am trying to build a client program using Boost on MSVC8 with the "Disable Language Extensions" /Za compilation flag. visual.hpp contains the following code // disable Win32 API's if compiler extentions are // turned off: // #ifndef _MSC_EXTENSIONS # define BOOST_DISABLE_WIN32 #endif win32.hpp contains: #ifndef BOOST_DISABLE_WIN32 // WEK: Added #define BOOST_HAS_FTIME #define BOOST_WINDOWS 1 #endif So, the preprocessor defines BOOST_DISABLE_WIN32 and doesn't define BOOST_WINDOWS. This doesn't sound right, and causes problems with Boost.ASIO where the Windows header files are conditionally included using #if defined(BOOST_WINDOWS) || defined(__CYGWIN__) which clearly evaluates FALSE. I consider this a bug in the boost config compiler detection rather than the asio library. Has anyone compiled with /ZA on MSVC? Thanks -- Craig Craig Henderson <http://craighenderson.co.uk/> http://www.craighenderson.co.uk http://www.siteupdatenotification.com

2 1

[task] new version 0.3.0
by k-oli＠gmx.de 17 Sep '09

17 Sep '09

I've uploaded a new version of boost.task - I hope someone will give me some feedback. regards, Oliver

1 0

cannot pass objects of non-POD type ‘class boost::detail::shared_count’ through ‘...’; call will abort at runtime
by Dave Steffen 17 Sep '09

17 Sep '09

Peter Dimov wrote: > I wrote: >> >>( Just tried to compile my project with GCC 4.3 and Boost 1.40. (It >> compiles and works just fine with Boost 1.38.) >> >> As part of a home-built thread-locking shared pointer thing, we have >> this code: [...] > > The signature of sp_enable_shared_from_this has changed, it now takes a > pointer to a shared_ptr as its first argument. Look at the current > shared_ptr constructor: > > template<class Y> > explicit shared_ptr( Y * p ): px( p ), pn( p ) // Y must be complete > { > boost::detail::sp_enable_shared_from_this( this, p, p ); > } > > Relying on implementation details has its maintenance costs. :-) Yeah. There are actually much better ways to do this now, like Boost threads and some other things, that weren't available when we started the project. It's also true that some refactoring would make the whole point moot, but I was really hoping to avoid tackling that on the current contract. > You'll probably need to refactor shared_locking_ptr to contain (or > privately derive from) a shared_ptr. ... which, arguably, we could have done in the first place. I'm inclined to refactor the whole issue out of our code at this point. :-) Anyway, thanks for the reply. I'm off to refactor. -- Dave Steffen - Software Engineer Numerica Corporation (www.numerica.us <http://www.numerica.us/> ) 4850 Hahns Peak Drive, Suite 200 Loveland, Colorado 80538 main (970) 461-2000 x 227 direct (970) 612-2327 fax (970) 461-2004 Email: dave.steffen(a)numerica.us k

1 0

[DateTime] valgrind warns on uninitialized jump
by Christoph Duelli 17 Sep '09

17 Sep '09

[from strings_from_facet.hpp, line 52] for (int m=0; m < 12; m++) { tm tm_value; tm_value.tm_mon = m; stringstream_type ss; ostream_iter_type oitr(ss); std::use_facet<time_put_facet_type>(locale).put(oitr, ss, ss.fill(), &tm_value, &*outfmt.begin(), &*outfmt.begin()+outfmt.size()); months.push_back(ss.str()); } valgrind (3.5.0, run on Linux, gcc 4.1.2, libstdc++ 6.0.8) reports: ==13166== 1 errors in context 1 of 1: ==13166== Conditional jump or move depends on uninitialised value(s) ==13166== at 0x41D793D: strftime_l (in /lib/libc-2.4.so) ==13166== by 0x40EE600: std::__timepunct<char>::_M_put(char*, unsigned int, char const*, tm const*) const (in /usr/lib/libstdc++.so.6.0.8) ==13166== by 0x40AC9DA: std::time_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::do_put(std::ostreambuf_iterator<char, std::char_traits<char> >, std::ios_base&, char, tm const*, char, char) const (in /usr/lib/libstdc++.so.6.0.8) ==13166== by 0x40AAD95: std::time_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::put(std::ostreambuf_iterator<char, std::char_traits<char> >, std::ios_base&, char, tm const*, char const*, char const*) const (in /usr/lib/libstdc++.so.6.0.8) The "error" goes away when tm_value.tm_hour is initialized to 0. (No idea why. Might be a bug in libstdc++) Best regards

1 0

Formal Review of Boost.Polygon is halfway through and no actual reviews so far
by Fernando Cacciola 17 Sep '09

17 Sep '09

Dear Developers, The formal review of the Boost.Polygon is halfway through and, while there was some useful discussion, there are still no "actual" reviews (where you clearly vote for inclusion and rejection). If you are interested in a geometric oriented library please try to make the time to post a formal review by the end of September 2 :) Best regards Fernando Cacciola Review Manager

4 7

Boost Review - changes to code being reviewed during the review?
by Paul A. Bristow 17 Sep '09

17 Sep '09

During most reviews, authors make changes to the code being reviewed. Some have questioned if this is 'allowed'. IMO, this is not only allowed but highly desirable - otherwise we will never get anywhere! But it can lead to confusion about exactly what is being reviewed. Now that we have SVN that keeps all changes and allows reasons to be recorded in the log, would it be useful for reviewers to quote the revision of the code that they are reviewing? Reviewers might include updates to say if the authors changes had solved problems, or changed their views. Paul --- Paul A. Bristow Prizet Farmhouse Kendal, UK LA8 8AB +44 1539 561830, mobile +44 7714330204 pbristow(a)hetp.u-net.com

1 0

Graph cut questions
by David Doria 17 Sep '09

17 Sep '09

1) If I do this: (with any of the max_flow algorithms, kolmogorov is just used as an example) double flow = kolmogorov_max_flow(g, SourceNode, SinkNode); I get the value of the max flow, but how do I tell which nodes of g belong to the "source side" of the graph and which nodes belong to the "sink side"? (thinking of it as a min cut rather than a max flow problem) 2) Is it possible to tell the max flow algorithm to use multiple sources/sinks? 3) The max_flow functions seem to require a source and sink to be specified. Shouldn't you be able to find the minimum cut that partitions the graph into two parts even without specifying a source/sink? 4) Currently you must use a bidirectional graph, and specify an edge_reverse_t in the graph traits, then set the reverse edge for every edge. a) this is pretty complicated for someone who is unfamiliar with generic programming. b) If an undirected graph is used, the algorithm should automatically take care of adding these reverse edges if they are required for the cut to be performed. Can these be considered as feature requests if they are not currently possible? I have not found a more promising graph library for c++, so it would be nice if BGL could be molded into the one everyone would like to use! Thanks, David

2 4

Re: [boost] [GIL] image rescale algorithms
by Est 16 Sep '09

16 Sep '09

Nicolas, One last, small thing. I would rename bicubic_filter in filters.hpp to mitchell_filter. Bicubic filter is a common name for bspline or photoshop style filters and mitchell is different. I think rgba32f_pixel_t is a good model for hdr pixels. I don't see the 0..1 range in floating point channels as limits. And GIL does not enforce them in any way. They only define a mapping between integer and floating point channels. In this case (rescale), clamping is an "artifact" of using integer channels and filters with possibly negative weights. I did some informal profiling, on a dual core machine, using the bicubic filter, I got this Big images: rescale serial took 9167.86 milliseconds (9.16786 sec) rescale parallel took 5055.94 milliseconds (5.05594 sec) Small images: rescale serial took 1923.46 milliseconds (1.92346 sec) rescale parallel took 1104.4 milliseconds (1.1044 sec) Est.

2 1

[GIL] image rescale algorithms
by Nicolas Lelong 16 Sep '09

16 Sep '09

Hi, I'm still working on updating my image management codebase, and I noticed that GIL does come only with by a very limited image rescaling/resampling algorithm (in gil/extension/numeric/resample.hpp) which does proper filtering for upsampling an image. As I need more robust image resampling, I came up with a source code for GIL, inspired by FreeImage implementation<http://freeimage.cvs.sourceforge.net/viewvc/freeimage/FreeImage/Source/Free…>; this code is available here :: http://code.google.com/p/rotoglup-scratchpad/source/browse/trunk/#trunk/rtg… This implementation is certainly not as generic as it could be, and could certainly benefit from 'gil concept checking' and various improvements ; I tried to make the code more 'readable' than 'efficient', and as I'm not really at ease with template metaprogramming, I may have missed a few points. For example, I think the mechanism I use to select the intermediate pixel format (used to store the averaged pixels during resizing) may be improved, and that there must be a way to let the user select a better pixel format if needed. I came up with virtual rescale view type, that allows to seamlessly rescale virtual views of any kind - it is not very efficient, but can be proved useful. I tried, as much as possible, to provide access to separable rescale functions (X & Y) so that users can control when/how (or whether) they should allocate the intermediate view for image rescaling. Feel free to use this work, and I'd be very happy to have some feedback on things that could be improved. The main functions defined are, in rescale.hpp<http://code.google.com/p/rotoglup-scratchpad/source/browse/trunk/rtgu/image…>:: // horizontal rescale only, rescale src view into dst view, matching dst view width template <typename SrcView, typename DstView, typename Filter> inline void rescale_cols(const SrcView& src, const DstView& dst, const Filter& filter); // vertical rescale only, rescale src view into dst view, matching dst view height template <typename SrcView, typename DstView, typename Filter> inline void rescale_rows(const SrcView& src, const DstView& dst, const Filter& filter); // rescale src view into dst view, matching dst view dimensions template <typename SrcView, typename DstView, typename Filter> inline void rescale(const SrcView& src, const DstView& dst, const Filter& filter); in rescale_any_view.hpp<http://code.google.com/p/rotoglup-scratchpad/source/browse/trunk/rtgu/image…>:: template <typename ViewTypes, typename Filter> inline void rescale_any_view(any_image_view<ViewTypes>& src, any_image_view<ViewTypes>& dst, const Filter& filter); in rescale_virtual_view.hpp<http://code.google.com/p/rotoglup-scratchpad/source/browse/trunk/rtgu/image…>:: // view factories template <typename SourceView, typename Filter> typename rescale_x_view_type<SourceView>::view_t rescale_x_view(SourceView const& view, typename SourceView::coord_t dst_width, const Filter& filter); template <typename SourceView, typename Filter> typename rescale_y_view_type<SourceView>::view_t rescale_y_view(SourceView const& view, typename SourceView::coord_t dst_height, const Filter& filter); template <typename SourceView, typename Filter> typename rescale_view_type<SourceView>::view_t rescale_view(SourceView const& view, typename SourceView::coord_t dst_width, typename SourceView::coord_t dst_height, const Filter& filter); and a few filters<http://code.google.com/p/rotoglup-scratchpad/source/browse/trunk/rtgu/image…>are provided. Cheers, Nicolas. **

2 4