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[voronoi]medial axis
by Louis Lavery 19 Sep '13

19 Sep '13

[mods: I posted this a few days ago, and that post was acknowledged etc (it was my first post as a new subscriber) but I haven't receieved a copy myself and cannot find it in the archives - perhaps I should be more patient?] Hello, I'm hoping to use boost voronoi to construct the (internal) medial axis for closed shapes (with holes). I need to work out which vertices of the voronoi are inside, outside and on a boundary. So my first goal is to determine which vertices correspond to the ends of the input segments (boundary vertices). The way I do this at the moment, is to look at each edge and test if its source vertex, vertex0(), is equal to either end point of the segment contained by the edge's cell. (1) If it is then it's a boundary vertex otherwise it's not. Is that correct? (2) When comparing a vertex with an input point can I do an exact compare (==) or should I use a tolerance (epsilon)? Thanks, fuzzy.

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[cpo-proposal] About mixout container for polymorphic objects
by Santiago Tapia 17 Sep '13

17 Sep '13

Hi all, I have design a new concept of container to be part of the cpo library. In summary, those containers will break down the inserted objects into some elementary parts. Why do that? Short answer: to save memory. Long answer: Because the alignment requirement of data members in an object could be very different, in a range from 1 byte to 16 bytes, structs or classes use padding to provide the correct location for members. That means an object size could be significantly greater than the sum of its members sizes. Even more, when dealing with polymorphic objects, the size is increased a little more due to the pointer to the table of virtual methods. I will try to outline the alternative solution, obviously, the implementation will be part of the container, the user will not need to know the details. ---- Example:----- #include <cstdlib> #include <iostream> #include <vector> class output { public: virtual void print(std::ostream& out) = 0; }; class integer { public: integer(short a_ = 0) : a(a_) { } short a; }; class character { public: character(char c_ = 'a') : c(c_) { } char c; }; class data { public: data(double x_ = 0) : x(x_) { } double x; }; class my_object : public integer, public data, public character, public output { public: my_object(int show = 1) : integer(rand() % 100) , data(1.0*rand()/RAND_MAX) , character('a' + rand() % 10) { if (show) print(std::cout); } virtual void print(std::ostream& out) { std::cout << a << "\t" << x << " \t" << c << "\n"; } }; void insert( std::vector<integer>& v_int, std::vector<data>& v_data, std::vector<character>& v_char, const my_object& o) { v_int.push_back( o ); v_data.push_back( o ); v_char.push_back( o ); } void iterate( std::vector<integer>& v_int, std::vector<data>& v_data, std::vector<character>& v_char ) { my_object o(0); unsigned i; for ( i = 0; i < v_int.size(); ++i) { static_cast<integer&>( o ) = v_int[i]; static_cast<data&>( o ) = v_data[i]; static_cast<character&>( o ) = v_char[i]; o.print(std::cout); } } int main(int, char**) { std::cout << "sizeof(my_object): " << sizeof(my_object) << "\n"; std::vector<integer> v_int; std::vector<data> v_data; std::vector<character> v_char; std::cout << "--- inserting (random) objects ---\n"; unsigned i; for ( i = 0; i < 5; ++ i ) { insert( v_int, v_data, v_char, my_object() ); } std::cout << "--- show content ---\n"; iterate(v_int, v_data, v_char); return 0; } ---- Output: (32 bit PC) ---- sizeof(my_object): 20 --- inserting (random) objects --- 83 0.394383 h 15 0.911647 f 86 0.76823 j 21 0.477397 h 90 0.513401 d --- show content --- 83 0.394383 h 15 0.911647 f 86 0.76823 j 21 0.477397 h 90 0.513401 d Final comment. In this example, all the std::vector objects will be part of the mixout container. The user will only use the insert method and the container iterator that will dereference to output& (template parameter in the container). Just in this simple example the implementation saves aproximately n* (20 - (8+2+1) = 9) bytes, being n the number of instances of my_object. Comments are wellcome. Best regards, Santiago Tapia

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[svn] pre-commit hook/mime-type
by Tim Blechmann 17 Sep '13

17 Sep '13

hi all, is it possible that the pre-commit hook had changed recently? not sure if this was intended, but it currently breaks the use of git-svn, which imo is a huge inconvenience: -- tim@moka-mac:~/Documents/boost-trunk-git/boost$ git svn dcommit Committing to https://svn.boost.org/svn/boost/trunk ... A boost/sync/detail/generic/event_cv_emulation.hpp A boost/sync/detail/windows/event.hpp A boost/sync/event.hpp A libs/sync/test/event_test.cpp ERROR from SVN: A repository hook failed: Commit blocked by pre-commit hook (exit code 1) with output: /home/subversion/boost/hooks/check-mime-type.pl: trunk/boost/sync/detail/generic/event_cv_emulation.hpp : svn:mime-type is not set trunk/boost/sync/detail/windows/event.hpp : svn:mime-type is not set trunk/boost/sync/event.hpp : svn:mime-type is not set trunk/libs/sync/test/event_test.cpp : svn:mime-type is not set Every added file must have the svn:mime-type property set. In addition text files must have the svn:eol-style property set. For binary files try running svn propset svn:mime-type application/octet-stream path/of/file For text files try svn propset svn:mime-type text/plain path/of/file svn propset svn:eol-style native path/of/file You may want to consider uncommenting the auto-props section in your ~/.subversion/config file. Read the Subversion book (http://svnbook.red-bean.com/) Chapter 7, Properties section, Automatic Property Setting subsection for more help. Also, see http://svn.boost.org/trac/boost/wiki/BoostSubversion W: b7ab541813d43b7d74b44f57eb04c2625ce305a7 and refs/remotes/git-svn differ, using rebase: :040000 040000 4b2ab78eaa8f1e5fa80761a327da5066ca15d465 73aa096ac4b16618132d6d012e964b1790542c8f M boost :040000 040000 6146f06c45f590b38f76d123656cea13f24471d1 7a95e843ffc2f67fff874b6bd6c142b040423414 M libs Current branch master is up to date. ERROR: Not all changes have been committed into SVN, however the committed ones (if any) seem to be successfully integrated into the working tree. Please see the above messages for details. -- this used to work fine just a few days ago. was this done intentionally? if so, an announcement on the list with a comment on the implications for the git-svn users would have been good to see. best, tim

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[functional] New functor adaptors
by Tigran Hayrapetyan 17 Sep '13

17 Sep '13

Hello, Suppose we want to transform sequence of integers by doubling and adding 5 to each value (x = 2*x + 5 for all x in sequence). If using std::transform, then we need a functor which will for given "x" return "2*x + 5". My question is - is it possible to do it in C++98 style (without lambda expressions), and without writing additional functor class? As I understand, it's not. For doing that we need something like nesting functors into each other. Here we have "std::bind2nd( std::multiplies<int>(), 2 )" functor, and "std::bind2nd( std::plus<int>(), 5 )" functor, which must be nested to provide necessary functionality. I suggest something like "unary_result_translator" functor adapter, which is unary functor itself, and which will apply unary functor to result of another unary functor. The implementation of "unary_result_translator" can be something like this: template< typename Fn1, typename FnTrans > class unary_result_translator { public: typedef typename Fn1::argument_type argument_type; typedef typename FnTrans::result_type result_type; unary_result_translator( const Fn1& fn1, const FnTrans& fn_trans ) : fn1_( fn1 ), fn_trans_( fn_trans ) {} result_type operator()( const argument_type& arg ) const { return fn_trans_( fn1_( arg ) ); } const Fn1& fn1_; const FnTrans& fn_trans_; }; So, we will create our needed functor which converts "x" to "2*x + 5" by this: make_unary_result_translator( std::bind2nd( std::multiplies<int>(), 2 ), std::bind2nd( std::plus<int>(), 5 ) ) Of'course, unary_result_translator can be also used for more complex functors construction. Recently I used it for case-insensitive comparision of strings only with help of ::tolower. Similarly, there can be "binary_result_translator" which is binary functor itself, and which will apply unary functor to result of binary functor. Can that functor adaptors be useful? Or may be there is another way to do such things? Thanks for reading! Best Regards, Tigran Hayrapetyan

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Boost::lexical_cast<> under llvm 3.4
by Robert J Goedman 17 Sep '13

17 Sep '13

Hi, Has anyone tried boost::lexical_cast<> on clang++ based on llvm/clang++ 3.4? Or is it too early to use 3.4? Couldn't find any recent references to problems with lexical_cast (except from Mar 16, 2013 and older, but boost_1_54_0 does have that fix in it). No problems with llvm/clang++ 3.3, but on a test machine under 3.4 it produces the errors shown in below file lexical_cast-error.txt. The files are also at https://github.com/goedman/clang11-spirit-qi , in the Boost_lexical_cast directory. As far as I can see, all other parts of a spirit::qi project does build, the error occurs in a small print utility where lexical_cast<> is used.. Rob J. Goedman goedman(a)icloud.com

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Re: [boost] [threads] Memory leaks in Boost threading support? Version boost_1_53_0
by Vicente J. Botet Escriba 16 Sep '13

16 Sep '13

Le 15/09/13 16:58, Paul Morrison a écrit : > Hi Vicente, > > I got your note about the memory leak not being connected to > condition_variable, but this one seems to be... see png file attached... > > Any suggestions you may have would be appreciated! > > TIA > > Paul M. > > PS I wasn't sure how to make sure that my reply got back to you in > person! :-) No, what I mean is that my comment had nothing to be with the condition_variable memory_leak. Unfortunately, I have not found yet what could be the cause. If you can post a short example that reproduce the issue this would surely help. Best, Vicente

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[C++11] If you have an old class with a throwing destructor...
by Daryle Walker 16 Sep '13

16 Sep '13

I just got reminded of a breaking change in C++11 regarding this. Destructors without any exception specification in C++11 get `noexcept(true)` added to them. This means that pre-C++11 classes with throwing destructors turn into `std::terminate` bombs when imported to a C++11 project! I have two^H^H^Hthree such classes in Boost, so I just reported myself. (It's bug #9088, if you're curious.) Any other maintainers as stu^H^H^Henlightened as me should review their classes and add `noexcept(false)` when compiling in C++11 mode. If there are other libraries affected, maybe someone should make an en-masse bug ticket. Daryle W.

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[units] problems
by Robert Ramey 16 Sep '13

16 Sep '13

I want and need the boost.units functionality. I'm sure that this is what I want. But I've spend a lot of time going through the documentation and I'm having real difficulties figure out how to use this. There's a lot there so I feel that what I want must be in there somewhere. I've started going through the tutorial example and there are a couple of problems. First of all, it doesn't compile on my machine. Looking at the tutorial, it actually contains two programs - one of which is commented out. I tried the commented out one as well - it didn't compile either. Note that other than in the header, there are very few if any comments in this code. It doesn't qualify as a tutorial. What I expect to see is: #include <boost/units/quantity.hpp> #include <boost/units/systems/si/length.hpp> #include <boost/units/base_units/us/mile.hpp> void main(){ using namespace boost::units; using namespace boost::units::si; using namespace boost::units::us; quantity<length, float> l1; l1 = 1000.0 * meters; quantity<length, float> l2; l2 = 1.0 * miles; // compile error quantity<length, float> l3 = l1 + l2; } and I expect this to pretty much work. The documentation says " Implicit conversions between unit systems are allowed only when the reduced units are identical, allowing, for example, trivial conversions between equivalent units in different systems (such as SI seconds and CGS seconds)" so I expected that it can convert miles into kilometers. This is a disappointment - but I'll assume that the authors have a good reason for this. So I'm interest in figuring out how to fix this but the manual doesn't seem to help me. I know a huge amount of effort has been invested in this package, but I'm afraid this issue of documentation is a big obstacle to this package being used every where it could be. Note to authors of boost libraries. When you think you've got the documentation done, hand it to someone who isn't familiar with it and ask him to make a small example using the library in 30 minutes. If he can't do that, it's time to go back to work. Most users will give up if they can't get some sort of love back from the library in that amount of time. Robert Ramey

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Re: [boost] [threads] Memory leaks in Boost threading support? Version boost_1_53_0
by Paul Morrison 16 Sep '13

16 Sep '13

>> Hi Vicente, >> >> I got your note about the memory leak not being connected to >> condition_variable, but this one seems to be... see png file >> attached... >> >> Any suggestions you may have would be appreciated! >> >> TIA >> >> Paul M. >> >> PS I wasn't sure how to make sure that my reply got back to you in >> person! :-) > PPS having trouble reducing size of attachment - hope you can read it!

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[threads] Memory leaks in Boost threading support? Version boost_1_53_0
by Paul Morrison 14 Sep '13

14 Sep '13

I am running a number of Boost threads communicating via bounded buffers. My programs seem to run properly, but I get a number of memory leaks, usually 4- and 8- byte areas, although a few are longer. As far as I can tell, they are coming from inside Boost, as there is no mention of lines in my code. OTOH, although my code runs fine, it is quite possible that there are subtle errors in it! I am using _CRTDBG_MAP_ALLOC, which is being used correctly as it detected one area of my own that I was not freeing up, and that has been fixed. I am running VC++ 2010 Express on a 64-bit machine. Here is my memory leak display - I tried setting a few of the numbers as breakpoints, using_CrtSetBreakAlloc(), but most of them did not cause breaks. The first one broke at a new in > boost::detail::basic_condition_variable::get_wait_entry() Line 180 + 0x7 bytes C++ Why wouldn't this get freed up?! Note: <bad exception > looks ominous - where is it coming from?! Detected memory leaks! Dumping objects -> {8624} normal block at 0x02312550, 4 bytes long. Data: <HC1 > 48 43 31 02 {8615} normal block at 0x0015F8F8, 4 bytes long. Data: <h!1 > 68 21 31 02 {8602} normal block at 0x023117A0, 4 bytes long. Data: < 51 > F8 35 31 02 {5584} normal block at 0x02311760, 4 bytes long. Data: <@ > 40 F7 15 00 {4013} normal block at 0x0015F948, 4 bytes long. Data: < 1 > 00 17 31 02 {3924} normal block at 0x02314048, 4 bytes long. Data: < <1 > 20 3C 31 02 {3883} normal block at 0x02314008, 4 bytes long. Data: < +1 > D0 2B 31 02 {3862} normal block at 0x02313CA0, 4 bytes long. Data: <h!1 > 68 21 31 02 {445} normal block at 0x02314088, 4 bytes long. Data: < R1 > 88 52 31 02 {440} normal block at 0x023145F8, 4 bytes long. Data: <HC1 > 48 43 31 02 {430} normal block at 0x02314648, 4 bytes long. Data: < 51 > F8 35 31 02 {402} normal block at 0x02313FC0, 4 bytes long. Data: < 1 > 98 1D 31 02 {395} normal block at 0x023136B8, 4 bytes long. Data: < +1 > D0 2B 31 02 {382} normal block at 0x02313A18, 4 bytes long. Data: < 51 > F8 35 31 02 {355} normal block at 0x02312B90, 4 bytes long. Data: <HC1 > 48 43 31 02 {332} normal block at 0x023121E8, 4 bytes long. Data: <h > 68 F8 15 00 {316} normal block at 0x02311978, 4 bytes long. Data: <HC1 > 48 43 31 02 {298} normal block at 0x023117E0, 4 bytes long. Data: < 51 > F8 35 31 02 {270} normal block at 0x023106D0, 4 bytes long. Data: < 1 > E0 0E 31 02 {256} normal block at 0x02310C50, 4 bytes long. Data: < R1 > 88 52 31 02 {225} normal block at 0x0015FC30, 4 bytes long. Data: < > 90 F9 15 00 {217} normal block at 0x0015F5C0, 8 bytes long. Data: <l > 6C F5 15 00 00 00 00 00 {213} normal block at 0x0015E7B8, 8 bytes long. Data: < > 14 E7 15 00 00 00 00 00 {212} normal block at 0x0015E770, 8 bytes long. Data: < > EC E6 15 00 00 00 00 00 {208} normal block at 0x0015D900, 8 bytes long. Data: <\ > 5C D8 15 00 00 00 00 00 {207} normal block at 0x0015D8B8, 8 bytes long. Data: <4 > 34 D8 15 00 00 00 00 00 {203} normal block at 0x0015CA48, 8 bytes long. Data: < > A4 C9 15 00 00 00 00 00 {202} normal block at 0x0015CA00, 8 bytes long. Data: <| > 7C C9 15 00 00 00 00 00 {198} normal block at 0x0015BB90, 8 bytes long. Data: < > EC BA 15 00 00 00 00 00 {197} normal block at 0x0015BB48, 8 bytes long. Data: < > C4 BA 15 00 00 00 00 00 {193} normal block at 0x0015ACD8, 8 bytes long. Data: <4 > 34 AC 15 00 00 00 00 00 {192} normal block at 0x0015AC90, 8 bytes long. Data: < > 0C AC 15 00 00 00 00 00 {188} normal block at 0x00159E20, 8 bytes long. Data: <| > 7C 9D 15 00 00 00 00 00 {187} normal block at 0x00159DD8, 8 bytes long. Data: <T > 54 9D 15 00 00 00 00 00 {183} normal block at 0x00158F68, 8 bytes long. Data: < > C4 8E 15 00 00 00 00 00 {182} normal block at 0x00158F20, 8 bytes long. Data: < > 9C 8E 15 00 00 00 00 00 {178} normal block at 0x001580B0, 8 bytes long. Data: < > 0C 80 15 00 00 00 00 00 {177} normal block at 0x00158068, 8 bytes long. Data: < > E4 7F 15 00 00 00 00 00 {173} normal block at 0x001571F8, 8 bytes long. Data: <Tq > 54 71 15 00 00 00 00 00 {172} normal block at 0x001571B0, 8 bytes long. Data: <,q > 2C 71 15 00 00 00 00 00 {168} normal block at 0x00156340, 8 bytes long. Data: < b > 9C 62 15 00 00 00 00 00 {167} normal block at 0x001562F8, 8 bytes long. Data: <tb > 74 62 15 00 00 00 00 00 {164} normal block at 0x00155B30, 8 bytes long. Data: < Z > D4 5A 15 00 00 00 00 00 {162} normal block at 0x001559E0, 8 bytes long. Data: < Y > 84 59 15 00 00 00 00 00 {160} normal block at 0x00155890, 8 bytes long. Data: <4X > 34 58 15 00 00 00 00 00 {158} normal block at 0x00155740, 8 bytes long. Data: < V > E4 56 15 00 00 00 00 00 {156} normal block at 0x001555F0, 8 bytes long. Data: < U > 94 55 15 00 00 00 00 00 {154} normal block at 0x001554A0, 8 bytes long. Data: <DT > 44 54 15 00 00 00 00 00 {152} normal block at 0x00155350, 8 bytes long. Data: < R > F4 52 15 00 00 00 00 00 {150} normal block at 0x00155200, 8 bytes long. Data: < Q > A4 51 15 00 00 00 00 00 {148} normal block at 0x001550B0, 8 bytes long. Data: <TP > 54 50 15 00 00 00 00 00 {146} normal block at 0x00154F60, 8 bytes long. Data: < O > 04 4F 15 00 00 00 00 00 {144} normal block at 0x00154E10, 8 bytes long. Data: < M > B4 4D 15 00 00 00 00 00 {140} normal block at 0x00154C40, 16 bytes long. Data: < K > 0C 1D EF 00 02 00 00 00 01 00 00 00 88 4B 15 00 {139} normal block at 0x00154BF0, 14 bytes long. Data: <bad exception > 62 61 64 20 65 78 63 65 70 74 69 6F 6E 00 {138} normal block at 0x00154B88, 44 bytes long. Data: < h > F4 1C EF 00 00 00 00 00 68 F8 EE 00 18 F8 EE 00 {135} normal block at 0x00154A98, 16 bytes long. Data: <\ 0J > 5C 1C EF 00 02 00 00 00 01 00 00 00 30 4A 15 00 {134} normal block at 0x00154A30, 44 bytes long. Data: <D 8 > 44 1C EF 00 00 00 00 00 88 F7 EE 00 38 F7 EE 00 Object dump complete.

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