September 2009 - Boost - lists.preview.boost.org

[polygon] late review
by Gordon Woodhull 20 Sep '09

20 Sep '09

Hi all, Sorry this is late - I intended to participate in the discussion, but the review schedule happened to intersect with an offline vacation. (Plus day job, school starting, etc.) Thank you, Luke, for submitting what I think is a very good start toward a Boost geometry library. I do not think the library is ready for inclusion in Boost at this time, but I believe it will be with further improvements. I would almost vote for acceptance with conditions, but the list is long and I think the concepts merit more discussion. Unfortunately I have not had time to take an in-depth look at the library; I have read some of the documentation and examples and it looks useable. So this is mostly a non-technical review of the issues raised by others. Also I offer a bit of "meta-review" of the review process for libraries that will continue to evolve and merge with other libraries. My application domain is mainly graph drawing (network visualization) but I might also use this in 2D screen graphics and games. For these purposes, the restriction to two dimensions is acceptable, and even the restriction to integer coordinates is mostly acceptable. However, I think the library name should reflect these restrictions. It will be some time (if ever) before a library can claim to be The geometry or polygon library. Boost has no merge process (if that's even possible), and neither Polygon nor GGL subsumes the other, so I think they should eventually be accepted in parallel, and merge concepts and algorithms over time. As I see it, this library provides two major contributions: 1. A set of concepts for VLSI and other 45/90 degree applications which can in the future be extended or bridged to other geometric problem domains, e.g. GIS, 3D, n-dimensional. 2. An extremely robust and (I believe) efficient polygon intersection algorithm. The interface still needs some work, but the concepts are a valuable first pass at defining this domain. I want to see some system of libraries that supports rectangles through arcs all the way up to splinegons. This isn't that, but I am patient. I will be interested to compare the advantages of concepts for polygons with holes versus the runtime version in GGL. I don't agree that accepting a library where the concepts/interface are incomplete or even wrong will pollute a future generalized geometry library. This library will just have to improved over time, and influenced by libraries from other domains. To mention just one specific interface problem: I don't like rect - int meaning shrink the rectangle. I think that everyone is going to have strong opinions about what operators they like and dislike and I hope that some future geometry library will allow choosing different sets for different domains. The intersection algorithm is very, very cool and I hope the ideas can be extended someday by someone to provide robust intersection of arcs and splines. I don't yet understand whether this is possible. I agree with those who would like to see lazier evaluation to run the intersection algorithm on as much as possible. Luke and Barend, I'm sorry but I don't believe either of your benchmarks. I think you are choosing problems that suit each of your libraries. This is understandable, but we will need to build a comprehensive suite of examples from many different domains to learn which algorithms are actually faster in which situations. Meta-review I admire the Boost process for protecting authorial control over libraries. However, one consequence is that two very important requirements, maintenance and cooperation, are only ensured indirectly by vigorous debate. 1. Maintenance. This is not really addressed by the Boost rules or review process, except to remind authors that they will be responsible for maintenance or for finding a new maintainer. There is no way to compel authors to respond to their users except for the threat of library removal which IIUC has almost never happened. So one of my essential criteria in reviewing a library - I've only reviewed one other library but followed many other reviews closely - is the attitude of the author toward changes requested. Users are inevitably going to have new requirements. Luke definitely seems willing to make the changes that are needed to get this into Boost, and I trust that he'll continue to help it adapt. I am slightly concerned that Intel will not allow the library to depend on Boost because I think that will slow down improvement. In particular I think operator customization and lazy evaluation would be helped by using Proto. I hope Intel will allow this. Or maybe that's the scope of a different library. 2. Cooperation. Boost has no rules or process for making libraries work together, never mind merging them. Maybe there is some work to be done here. But people will naturally want to make their libraries compatible if they're under the same umbrella. Competition is also a healthy human drive, but it's especially productive when there is some basis of cooperation, as I think there is between Luke and Barend, despite how nerves may have frayed during this review. I hope that both libraries are accepted, when ready, and that the authors and others interested in a "universal" Boost geometry library work to find the commonalities and connections. Fervently waiting, Gordon

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Formal Review: Boost.Polygon starts today August 24, 2009
by Fernando Cacciola 20 Sep '09

20 Sep '09

Dear Developers, The formal review of the Boost.Polygon library by Lucanus Simonson starts today, August 24, 2009 and will finish September 2, 2009. I really hope to see your vote and your participation in the discussions on the Boost mailing lists! --------------------------------------------------- About the library: The boost polygon library provides algorithms focused on manipulating planar polygon geometry data. Specific algorithms provided are the polygon set operations (intersection, union, difference, disjoint-union) and related algorithms such as polygon connectivity graph extraction, offsetting and map-overlay. These so-called Boolean algorithms are of significant interest in GIS (Geospatial Information Systems), VLSI CAD as well al other fields of CAD, and many more application areas, and providing them is the primary focus of this library. The polygon library is not intended to cover all of computational geometry in its scope, and provides a set of capabilities for working with coordinates, points, intervals and rectangles that are needed to support implementing and interacting with polygon data structures and algorithms. Specifically, 3d and non-Cartesian/non-planar geometry is outside of the scope of the polygon library The design philosophy behind the polygon library was to create an API for invoking the library algorithms it provides on user geometry data types that is maximally intuitive, minimally error-prone and easy to integrate into pre-existing applications. C++-concepts based template meta-programming combined with generic operator overloading meets these design goals without sacrificing the runtime or memory efficiency of the underlying algorithms. This API makes the following code snippet that operates on non-library geometry types possible: void foo(list<CPolygon>& result, const list<CPolygon>& a, const list<CPolygon>& b, int deflateValue) { CBoundingBox domainExtent; using namespace boost::polygon::operators; boost::polygon::extents(domainExtent, a); result += (b & domainExtent) ^ (a - deflateValue); } The source is available at http://svn.boost.org/svn/boost/sandbox/gtl/boost/polygon/ And the documentation is at http://svn.boost.org/svn/boost/sandbox/gtl/doc/index.htm --------------------------------------------------- Please always state in your review, whether you think the library should be accepted as a Boost library! Additionally please consider giving feedback on the following general topics: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? - Are you knowledgeable about the problem domain? Best Regards Fernando Cacciola Review Manager

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SQL client library ?
by Jean-Louis Leroy 19 Sep '09

19 Sep '09

What's the situation with SQL client libraries (similar to Rogue Wave's DBTools.h++) ? I know that there's a boost_sql_cli in the Vault, but it doesn't seem to make much progress. I have also heard about plans to bring Soci into Boost. Thanks, Jean-Louis

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Error building Boost.MPI on WinXP with MPICH2
by Craig Henderson 19 Sep '09

19 Sep '09

I am trying to build Boost.MPI for the first time. I've downloaded and installed MPICH2 on my Windows XP machine, and added "using mpi ;" to tools/build/v2/user-config.jam file, and the mpich2/bin to the path. When I run bjam, I get the following output. ------------------------------------------------------ C:\root\Development\Library\Boost\boost_1_39_0>..\bjam --with-mpi The system cannot find the path specified. The system cannot find the path specified. The system cannot find the path specified. MPI auto-detection failed: unknown wrapper compiler mpic++ Please report this error to the Boost mailing list: http://www.boost.org You will need to manually configure MPI support. WARNING: No python installation configured and autoconfiguration failed. See http://www.boost.org/libs/python/doc/building.html for configuration instructions or pass --without-python to suppress this message and silently skip all Boost.Python targets Building C++ Boost. ------------------------------------------------------ The environment runs for building all other Boost libraries. Any ideas what's wrong or how to diagnose the problem? Thanks -- Craig Craig Henderson http://www.craighenderson.co.uk http://www.siteupdatenotification.com

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cannot pass objects of non-POD type ‘class boost::detail::shared_count’ through ‘...’; call will abort at runtime
by Dave Steffen 19 Sep '09

19 Sep '09

Hi Folks [ Sorry if this gets posted twice; my company email server changed my email address, and I think my first post got bounced. Argh.] 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: /// Constructor from pointer to complete type template<class Y> explicit shared_locking_ptr( Y * p ): px( p ), pn( p ) // Y must be complete { boost::detail::sp_enable_shared_from_this( pn, p, p ); } which now produces this result: ../util/thread/shared_locking_ptr.hpp:57:9: warning: cannot pass objects of non-POD type ‘class boost::detail::shared_count’ through ‘...’; call will abort at runtime In Boost 1.38, the relevent code in shared_ptr.hpp was this AFAICT: #ifdef _MANAGED [ ... ] #else // _MANAGED [...] inline void sp_enable_shared_from_this( shared_count const & /*pn*/, ... ) { } #endif // _MANAGED In 1.40, it's been changed to #ifdef _MANAGED [...] #else // _MANAGED inline void sp_enable_shared_from_this( ... ) { } #endif // _MANAGED Does anyone know why the change? Has anybody else seen this problem? It seems to me that GCC is correct, and that although it's an empty function so it doesn't matter anyway, the earlier version is preferable. Alternately, does anyone know of a way to silence GCC's warning? -- Dave Steffen, Ph.D - 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

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[iostreams][bug] Uncaught exception in destructor when using file_descriptor
by Sylvester-Bradley, Gareth 19 Sep '09

19 Sep '09

https://svn.boost.org/trac/boost/ticket/2932 I hope it's appropriate to ping the list about this issue, which was reported 4 months ago and has not been fixed in 1.39.0 or on the trunk. If closing a file descriptor fails, file_descriptor::impl::~impl() (or file_descriptor_impl::~file_descriptor_impl() on the trunk) throws an exception. This has the potential to happen during stack unwinding, causing immediate std::terminate(). Since the fix appears to be a trivial addition of try { /*...*/ } catch (...) {} it'd be a shame if this wasn't fixed in 1.40.0. Cheers, Gareth ************************************************************************ The information contained in this message or any of its attachments may be confidential and is intended for the exclusive use of the addressee(s). Any disclosure, reproduction, distribution or other dissemination or use of this communication is strictly prohibited without the express permission of the sender. The views expressed in this email are those of the individual and not necessarily those of Sony or Sony affiliated companies. Sony email is for business use only. This email and any response may be monitored by Sony to be in compliance with Sony's global policies and standards

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Policy related to the time between a library is accepted and released?
by vicente.botet 18 Sep '09

18 Sep '09

Hi, On "Past Review Results and Milestones" (http://www.boost.org/community/review_schedule.html) we see the following There are 3 libraries accepted more than 1 year ago that are commited on trunk but not yet on release . * Property Tree Marcin Kalicinski May 20, 2006 * Forward (fast-track) Tobias Schwinger John Torjo December 3, 2007 - December 7, 2007 * Factory (fast-track) Tobias Schwinger John Torjo December 17, 2007 - December 21, 2007 There are 2 libraries accepted more than 1 year ago but not yet commited on trunk. * Time Series Eric Niebler August 17, 2007 * Floating Point Utilities Johan Råde Mars 8, 2008 There are 2 libraries accepted provisionally more than 1 year ago but without any outcome. * Switch Steven Watanabe January 13, 2008 * Phoenix Joel de Guzman Hartmut Kaiser September 21, 2008 - September 30, 2008 I understand that the authors have a lot of other things to do, but one year seems to me a good delay. Should't Boost have a policy related to the time between a library is accepted and released? If yes, which one? Best regards, Vicente

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Need help with workaround for MSVC bug
by Emil Dotchevski 18 Sep '09

18 Sep '09

On MSVC, the following correct code produces error C2896: 'void operator ||(T,void (__cdecl *)(tag<X>))' : cannot use function template 'void bar(tag<X>)' as a function argument. struct foo { }; template <int X> struct tag { }; template <int X> void bar( tag<X> ) { } template <class T,int X> void operator||(T, void(*)(tag<X>)) { } int main() { foo()||bar<1>; } My goal is to have an operator|| overload that deduces tag<X> implicitly, but without using parenthesis, that is, foo()||bar<1>() wouldn't be satisfactory. Doesn't seem possible, but still I decided to ask. Any ideas? Emil Dotchevski Reverge Studios, Inc. http://www.revergestudios.com/reblog/index.php?n=ReCode

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[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

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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

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