March 2010 - Boost - lists.preview.boost.org

bad include guards
by Steven Watanabe 26 Jan '17

26 Jan '17

AMDG The following pairs of files have identical include guards ./boost/concept_check/general.hpp ./boost/concept/detail/msvc.hpp ./boost/concept_check/msvc.hpp ./boost/concept/detail/msvc.hpp ./boost/filesystem/cerrno.hpp ./boost/cerrno.hpp ./boost/interprocess/containers/tree.hpp ./boost/interprocess/containers/detail/tree.hpp ./boost/mpl/min_max.hpp ./boost/mpl/max.hpp ./boost/mpl/vector/aux_/front.hpp ./boost/mpl/list/aux_/front.hpp ./boost/multi_index/identity_fwd.hpp ./boost/multi_index/identity.hpp ./boost/python/pointee.hpp ./boost/python/detail/pointee.hpp ./boost/spirit/phoenix/closures.hpp ./boost/lambda/closures.hpp ./boost/xpressive/proto/v1_/proto_typeof.hpp ./boost/xpressive/proto/proto_typeof.hpp ./libs/config/test/boost_no_dep_nested_class.ipp ./libs/config/test/boost_has_vc6_mem_templ.ipp ./libs/config/test/boost_no_mem_templates.ipp ./libs/config/test/boost_has_vc6_mem_templ.ipp ./libs/config/test/boost_no_std_allocator.ipp ./libs/config/test/boost_has_vc6_mem_templ.ipp ./libs/conversion/test.hpp ./libs/any/test.hpp ./libs/interprocess/example/print_container.hpp ./libs/interprocess/example/printcontainer.hpp ./libs/interprocess/test/expand_bwd_test_template.hpp ./libs/interprocess/test/allocation_test_template.hpp ./libs/interprocess/test/printcontainer.hpp ./libs/interprocess/example/printcontainer.hpp ./libs/interprocess/test/print_container.hpp ./libs/interprocess/example/printcontainer.hpp ./libs/iostreams/test/detail/utf8_codecvt_facet.hpp ./boost/detail/utf8_codecvt_facet.hpp ./libs/regex/test/regress/test_regex_search.hpp ./libs/regex/test/regress/test_partial_match.hpp ./libs/serialization/test/C.hpp ./libs/serialization/test/A.hpp ./libs/xpressive/perf/regex_comparison.hpp ./libs/regex/performance/regex_comparison.hpp ./tools/inspect/time_string.hpp ./tools/common/time_string.hpp In Christ, Steven Watanabe

5 8

Why no non-null smart pointers?
by Ross MacGregor 29 Apr '14

29 Apr '14

I just created a very small smart pointer libary for our project. It will contain two types of shared pointers: SharedHandle and NullableSharedHandle. SharedHandle will be a shared pointer that cannot be null by ensuring a non-null construction while NullableSharedHandle will basically be a typedef for boost::shared_ptr. I firmly believe that code can be made more reliable by minimizing the use of nullable pointers. To this end, I think it is important that we start using non-null pointer types. Ideally the compiler would be able to understand a non-null pointer and catch bugs at compile time, but I think we can still improve things with a few runtime checks. If we make sure that a shared pointer is constructed with a non-null pointer and ban any reset() type methods, we guarentee that it points to something. This can be beneficial for the following reasons: 1. Any function that uses this type will no longer be burdened with precondition checks to make sure variables of this type are not null. 2. It's type is simply more explicit and better explains its function. 3. Moving the non-null check to the creation phase will reduce the possibility of encountering null pointer exceptions at runtime (assuming there are many more pointer references than constructor calls). So my little pointer library seems to make a lot of sense, but if so why hasn't this simple smart pointer variation made it into boost yet? Has this been discussed somewhere already? My search on non-null smart pointers is not revealing much discussion on the topic. Regards, Ross

9 16

[#pragma once]
by Sid Sacek 18 Nov '12

18 Nov '12

I've worked with the MSVC, Sun and GCC compilers. Each one of them supports #pragma once. Is there any reason to wrap this pragma within #ifdefs? Are there any compilers out there today that don't support this #pragma? #if defined( _MSC_VER ) && ( _MSC_VER >= 1020 ) # pragma once #endif Could we change this coding pattern so that it no longer looks like MSVC is being selfish? -Sid Sacek

17 20

[interprocess] message_queue hangs when another process dies
by Sergei Politov 03 Nov '11

03 Nov '11

Hi, I have found the following problem with message_queue on win32 (MSVC 2008 + Windows Vista). Suppose we have 2 processes, one sends messages to queue, another reads them. When reading process dies (for instance using End process) during message_queue.receive the another process hangs in send. As I found during investigation, it tries to lock interprocess mutex, but it is already locked by dead process. So this message queue instance becomes unusable. I attached the example. Steps to reproduce: 1) Start "mq.exe s" (i.e. with argument s) It outs: sender: $PID 2) Start mq.exe without arguments. It outs: receiver: $PID 0 1 2 3 4 This time sender outs: send done: 3) At this point the message queue is empty and receiver waits for messages. End it with Task Manager. 4) Enter some number in sender console and press Enter. 5) The sender hangs in message_queue.send Best Regards, Sergei

6 13

Re: [boost] [date_time] Time zone improvements
by Rutger ter Borg 25 May '11

25 May '11

Jeff Garland wrote: > Very cool :-) One question -- is there a portable solution where a user > could deploy a files onto a Windows system or is it a Unix only solution? > I'm fine with incorporating a *nix only solution because what your > suggesting will be a nice solution for *nix platforms, but it will need to > be clear that it's not portable. I don't see why it wouldn't be possible to deploy the (big-endian) binary files to any platform. Getting it into this binary form (using zone info compiler zic) may be harder to do cross-platform, but cygwin may help here. [snip] > As the primary maintainer of Boost date-time I can say with certainty that > there is interest in this functionality -- it's long been on my todo list > and I haven't had time to get to it. You can email me privately and we > can discuss all the details of how to get your code incorporated. I'll do! Regards, Rutger

5 9

[serialization] boost/serialization/path.hpp
by Johan Råde 21 Feb '11

21 Feb '11

There is no boost/serialization/path.hpp. I suggest the following: ---------------------------------------------------------------------------------------------------------------- #ifndef BOOST_SERIALIZATION_PATH_HPP #define BOOST_SERIALIZATION_PATH_HPP // MS compatible compilers support #pragma once #if defined(_MSC_VER) && (_MSC_VER >= 1020) #pragma once #endif #include <boost/config.hpp> #include <boost/filesystem/path.hpp> #include <boost/serialization/level.hpp> BOOST_CLASS_IMPLEMENTATION(boost::filesystem::path, boost::serialization::primitive_type) #ifndef BOOST_NO_STD_WSTRING BOOST_CLASS_IMPLEMENTATION(boost::filesystem::wpath, boost::serialization::primitive_type) #endif namespace boost { namespace serialization { template<class Archive, class String, class Traits> void serialize(Archive& ar, boost::filesystem::basic_path<String, Traits>& p, const unsigned int version) { String s; if(Archive::is_saving::value) s = p.string(); ar & boost::serialization::make_nvp("string", s); if(Archive::is_loading::value) p = s; } }} #endif //-------------------------------------------------------------------------------------------------------------- Comments? Any suggested improvements? --Johan Råde

5 11

[C++0x] Emulation of scoped enums
by Beman Dawes 16 Feb '11

16 Feb '11

The improved type safety of the C++0x scoped enum feature is attractive, so I'd like to start using it as it becomes available in compilers. See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2347.pdf for a description. Note that the committee changed the name from strongly typed enums to scoped enums. See the attached for a boost/detail header that provides macro wrappers that use scoped enums if available, otherwise fall back on C++03 namespaces and unscoped enums. It lets a library write: BOOST_SCOPED_ENUM_START(algae) { green, red, cyan }; BOOST_SCOPED_ENUM_END ... BOOST_SCOPED_ENUM(algae) sample( algae::red ); void func(BOOST_SCOPED_ENUM(algae)); and then a user can write: sample = algae::green; func( algae::cyan ); Comments or suggestions appreciated, --Beman // scoped_enum_emulation.hpp ---------------------------------------------------------// // Copyright Beman Dawes, 2009 // Distributed under the Boost Software License, Version 1.0. // See http://www.boost.org/LICENSE_1_0.txt // Generates C++0x scoped enums if the feature is present, otherwise emulates C++0x // scoped enums with C++03 namespaces and enums. The Boost.Config BOOST_NO_SCOPED_ENUMS // macro is used to detect feature support. // // Caution: only the syntax is emulated; the semantics are not emulated and // the syntax emulation doesn't include being able to specify the underlying type. // // See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2347.pdf for a // description of the feature. Note that the committee changed the name from // strongly typed enums to scoped enums. // // Sample usage: // // BOOST_SCOPED_ENUM_START(algae) { green, red, cyan }; BOOST_SCOPED_ENUM_END // ... // BOOST_SCOPED_ENUM(algae) sample( algae::red ); // void foo( BOOST_SCOPED_ENUM(algae) color ); // ... // sample = algae::green; // foo( algae::cyan ); #ifndef BOOST_SCOPED_ENUM_EMULATION_HPP #define BOOST_SCOPED_ENUM_EMULATION_HPP #include <boost/config.hpp> #ifndef BOOST_NO_SCOPED_ENUMS # define BOOST_SCOPED_ENUM_START(name) enum class name # define BOOST_SCOPED_ENUM_END # define BOOST_SCOPED_ENUM(name) name #else # define BOOST_SCOPED_ENUM_START(name) namespace name { enum enum_t # define BOOST_SCOPED_ENUM_END } # define BOOST_SCOPED_ENUM(name) name::enum_t #endif #endif // BOOST_SCOPED_ENUM_EMULATION_HPP

14 27

[process] How to run test cases
by Boris 23 Jan '11

23 Jan '11

As Boost.Process 0.3 has been released it would be great if the test cases are run on various platforms. So far I've tested Boost.Process on WinXP with MSVC 9.0, Cygwin with g++ 3.4.4 and Solaris with g++ 3.4.6 and Sun C++ 5.9. To make it as easy as possible for others to run the test cases here's a short description of how to proceed. Nearly all test cases depend on a program called "helpers". This program is built first and is started by many test cases as a child process. In order to find the program "helpers" the test cases must know its location. As there is no way to get the location at runtime it is hardcoded in the file libs/process/test/misc.hpp. As the location differs depending on what compiler is used YOU MUST CHECK FIRST THE PATH IN libs/process/test/misc.hpp! Otherwise most of the test cases will fail as they look for a program "helpers" in the wrong directory. As of today only those paths are correct and have been tested which are set for Windows, Cygwin and Solaris. Only after you have checked and maybe updated the path in libs/process/test/misc.hpp you should try to build and run the test cases: WinXP/MSVC 9.0 ************** With MSVC 9.0 you only need to open the Visual Studio 2008 Command Prompt, change to the directory with the test cases and run bjam: C:\boost_1_36_0\libs\process\test> ..\..\..\bjam.exe -q Cygwin/GCC 3.4.4 **************** On Cygwin it's important to know if the Boost libraries have been built for the POSIX or Windows API. By default Boost libraries on Cygwin use the Windows API. With the Windows API the Boost.Process test cases are not passed successfully though (there are compiler errors where I'm not sure currently if they are a Boost.Process problem and how they could be fixed). If you want to run the test cases on Cygwin you must (re-)build the Boost libraries to use the POSIX API: $ cd ~/boost_1_36_0 $ ./bjam cxxflags=-DBOOST_POSIX_API Afterwards you can run the test cases: $ cd ~/boost_1_36_0/libs/process/test $ ../../../bjam cxxflags=-DBOOST_POSIX_API -q Solaris/GCC 3.4.6 ***************** At first you have to put the following line in ~/user-config.jam: using gcc : : : <linker-type>sun ; Then start building the Boost libraries: $ cd ~/boost_1_36_0 $ ./bjam --toolset=gcc cxxflags=-mcpu=ultrasparc For the test cases to be passed successfully you must update Boost.Test. Change line 624 in ~/boost_1_36_0/boost/test/impl/execution_monitor.ipp temporarily to: - , m_CHLD_action( SIGCHLD, catch_system_errors, attach_dbg, alt_stack ) + , m_CHLD_action( SIGCHLD, false, attach_dbg, alt_stack ) It is important that the second parameter is false as the signal SIGCHLD should not be handled by the execution monitor and should not be reported as an error. Afterwards the test cases can be run: $ cd ~/boost_1_36_0/libs/process/test $ ../../../bjam --toolset=gcc cxxflags=-mcpu=ultrasparc -q Solaris/Sun C++ 5.9 ******************* Build the Boost libraries with the sun toolset: $ cd ~/boost_1_36_0 $ ./bjam --toolset=sun stdlib=sun-stlport For the test cases to be passed successfully you must update Boost.Test. Change line 624 in ~/boost_1_36_0/boost/test/impl/execution_monitor.ipp temporarily to: - , m_CHLD_action( SIGCHLD, catch_system_errors, attach_dbg, alt_stack ) + , m_CHLD_action( SIGCHLD, false, attach_dbg, alt_stack ) It is important that the second parameter is false as the signal SIGCHLD should not be handled by the execution monitor and should not be reported as an error. If you run the test cases now you'll get this compiler error for one test case: "../../../boost/asio/detail/socket_ops.hpp", line 218: Error: Cannot assign void* to char*. "../../../boost/asio/detail/socket_ops.hpp", line 229: Error: Cannot assign void* to char*. "../../../boost/asio/detail/descriptor_ops.hpp", line 66: Error: Cannot assign void* to char*. "../../../boost/asio/detail/descriptor_ops.hpp", line 72: Error: Cannot assign void* to char*. The bug has been reported to the Boost.Asio mailing list. If you want to build that one test case, too, you need to fix the two files in Boost.Asio 1.36.0 yourself. All the test cases can be built and run with: $ cd ~/boost_1_36_0/libs/process/test $ ../../../bjam --toolset=sun stdlib=sun-stlport -q

4 9

[SoC] BGL project idea
by Gautam Sewani 03 Jan '11

03 Jan '11

Hi, I am a Computer Science student hoping to contribute to Boost for this year's summer of code. I had a few questions regarding the BGL project idea (https://svn.boost.org/trac/boost/wiki/SoC2010#Boost.Graph) for SOC 2010. 1. I can think of only a few places where the suggested algorithms will be used. Does the community think that these algorithms are used frequently enough to put them in a library? How important does the community consider this project? 2. Will the project proposal be expected to include the API design? Thanks and Regards Gautam

5 29

boost::thread compiler error on SUN CC 5.9
by Urs Stotz 08 Jun '10

08 Jun '10

boost::thread give a compile error on SUN CC 5.9: /opt/SUNWspro/bin/CC +d -library=stlport4 -library=stlport4 -xcode=pic32 -erroff=wvarhidemem,hidevf,hidevfinvb -errtags=yes -features=tmplife -features=tmplrefstatic -g -mt -erroff=%none -KPIC -DBOOST_ALL_NO_LIB=1 -DBOOST_THREAD_BUILD_DLL=1 -DBOOST_THREAD_POSIX -I"." -c -o "bin.v2/libs/thread/build/sun-5.9/debug/stdlib-sun-stlport/threading-multi/pthread/thread.o" "libs/thread/src/pthread/thread.cpp" "libs/thread/src/pthread/thread.cpp", line 77: Error, badbinaryop: The operation "boost::shared_ptr<boost::detail::tss_cleanup_function> && void*" is illegal. "libs/thread/src/pthread/thread.cpp", line 588: Error, badbinaryop: The operation "boost::shared_ptr<boost::detail::tss_cleanup_function> || void*" is illegal. 2 Error(s) detected. make: *** [thread.o] Error 2 with this small patch it will compile: --- boost_1_42_0.org/libs/thread/src/pthread/thread.cpp 2009-10-19 11:18:13.000000000 +0200 +++ boost_1_42_0/libs/thread/src/pthread/thread.cpp 2010-02-10 13:48:25.037748000 +0100 @@ -74,7 +74,7 @@ namespace boost { current=next; ++next; - if(current->second.func && current->second.value) + if(current->second.func && (current->second.value != 0)) { (*current->second.func)(current->second.value); } @@ -585,7 +585,7 @@ namespace boost { (*current_node->func)(current_node->value); } - if(func || tss_data) + if(func || (tss_data != 0) ) { current_node->func=func; current_node->value=tss_data;

3 2

safe bool operator
by Domagoj Saric 18 May '10

18 May '10

While examining source and binary code for the various safe_bool/unspecified_bool_type implementations two issues can be noticed: - source code verbosity/repetition - binary code inefficiency The first issue is made worse by the fact that even this simple idiom is broken on some compilers ('pointed out' by workarounds in smart_ptr/detail/operator_bool.hpp) so workarounds must also be copied/'rediscovered'... The second issue (related to the usual implementation with member function pointers) has two sides, one is that taking the address of a function will force it to be included in the resulting binary even if it is never used or is always inlined and the second is that some compilers produce non-optimal code. For example for the following source code: boost::optional<int> test1; boost::optional<int> test2; __declspec( noinline ) void func() { if ( test1 ) test2 = *test1; } MSVC++ 8.0 and 9.0 will produce the following binary code ... 0F923A26 movzx eax,byte ptr [test1 (0F968210h)] 0F923A2D neg eax 0F923A2F sbb eax,eax 0F923A31 test eax,offset boost::optional_detail::optional_base<int>::is_initialized (0F923B9Eh) 0F923A36 je ... ... but if the if line is changed to if ( test1.is_initialized() ) the following code will be produced: ... 0F923A26 cmp byte ptr [test1 (0F968210h)],0 0F923A2D je ... ... At first I tried a solution that takes advantage of the fact that MSVC++ has plain-pointer-sized/register-sized member function pointers for plain single inheritance non virtual member functions and worked properly but than I found old discussions about the same subject: http://lists.boost.org/Archives/boost/2003/09/52846.php http://lists.boost.org/Archives/boost/2002/10/38624.php where the solution for MSVC++ was to use a pointer member data which gives the same results as my initial solution... Anyways I've attached a .hpp file with a draft implementation proposal (missing the compiler workarounds from smart_ptr/smart_ptr/detail/operator_bool.hpp for example) that uses both approaches... It enables a one liner implementation for a safe_bool operator: class my_class { public: bool some_is_valid_function() const; operator boost::unspecified_bool_type() const { return boost::make_safe_bool( some_is_valid_function() ); } //or by using a macro BOOST_SAFE_BOOL_FROM_FUNCTION( some_is_valid_function() ) } -- "What Huxley teaches is that in the age of advanced technology, spiritual devastation is more likely to come from an enemy with a smiling face than from one whose countenance exudes suspicion and hate." 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` ` end

7 9

[GSoC] Helping out Phoenix v3
by Joel Falcou 04 May '10

04 May '10

Joel and I pondered about getting a student from GSoC to help us complete the phoenix v3 port to proto. I currently have a few prototypes and ideas to extend it further but a few more hands are most welcome. Considering the schedule, I'll be compeltely free for mentoring this prospective student. Now, is it realistic and on topic for GSoC ?

9 33

Re: [boost] [repost][multiarray] Bug with boost::detail::multi_array::array_iterator on MSVC 2010RC?
by Thomas Klimpel 04 May '10

04 May '10

Jesse Perla wrote: > I have attached my test files. Any ideas or patches would be appreciated I could reproduce the problem with MSVC 2010beta2. I noticed that only the debug version fails to build. So I added the line #define _HAS_ITERATOR_DEBUGGING 0 and everything compiled fine. So the simplest solution is to add ADD_DEFINITIONS(-D_HAS_ITERATOR_DEBUGGING=0) to your CMakeLists.txt, which many people recommend in any case, because they claim that the debug version under MSVC would otherwise violate the "runtime complexity specifications" of the corresponding containers and iterators. (I don't know whether this is really true, but I really think that this workaround is not unreasonable.) But of course, you want to know whether this is a bug in boost::multi_array or a bug in MSVC 2010beta2. Before we come to that, another "workaround" would be to change multi_array/iterator.hpp:56 for , boost::random_access_traversal_tag to , std::random_access_iterator_tag This will most probably work, but would lying to the standard library, because the reference reference type of the corresponding iterator is not value_type& (but a proxy): http://lists.boost.org/boost-users/2006/11/23565.php What effectively happens it that the iterator gets the category "input_iterator", but std::copy wants to have an "output_iterator". I think I understand why the iterator doesn't satisfies the requirement of a "forward_iterator", but it's unclear to me why it didn't qualify as an "output_iterator". There is an "input_output_iterator_tag" in "boost/iterator/detail/facade_iterator_category.hpp", so it would have been possible for the iterator to be both "input_iterator" and "output_iterator". However, it seems to me that "input_output_iterator_tag" is never used in the Boost.Iterator library. I would have to read more about "output_iterator" to understand whether Boost.Iterator is correct here. With my current understanding of "output_iterator", I would say it's a bug in "boost/iterator/detail/facade_iterator_category.hpp". Perhaps somebody with more knowledge about "output_iterator" and Boost.Iterator can explain to me why an iterator using the "boost::random_access_traversal_tag" for the "CategoryOrTraversal" template parameter of "iterator_facade" will never get the category "output_iterator" (or "input_output_iterator_tag"). Regards, Thomas

4 6

Help with VeecoFTC - exception - cloning_test / msvc-9.0~wm5~stlport5.2
by Emil Dotchevski 24 Apr '10

24 Apr '10

Can someone help me figure out what's going on here: http://tinyurl.com/ybpbsp4 Thanks! Emil Dotchevski Reverge Studios, Inc. http://www.revergestudios.com/reblog/index.php?n=ReCode

3 5

[RangeEx] Where is the current version?
by Mathias Gaunard 19 Apr '10

19 Apr '10

Where is the current version (or a fairly recent version) of RangeEx? I can't find anything on the trunk, the sandbox or the vault.

5 13

[asio] read_until -- possibly misleading documentation?
by Richard Smith 15 Apr '10

15 Apr '10

The documentation for Boost.ASIO (which is otherwise very comprehensive) says of the boost::asio::read_until set of overloads: | Read data into a streambuf until a delimiter is | encountered. <http://www.boost.org/doc/libs/1_35_0/doc/html/boost_asio/reference/read_unt…> What the function actually does is to read blocks of data into the streambuf, and stop when the delimiter is found. This means that frequently data beyond the delimiter will be read into the streambuf. (And this is elaborated in more detail on the individual function's pages, if a reader looks there.) I appreciate that this behaviour is compatible with the documentation, but someone less familiar with ASIO could easily assume that the function will read as far as the delimiter and no further. (And I have just spent a fair amount of time debugging a piece of code where the author had made this assumption.) Could we change the summary documentation to read something like: | Read data into a streambuf at least until a delimiter is | encountered. The implementation may read beyond the | delimiter, but will not block when doing so. While I'm on the subject of ASIO documentation, I can't see any documentation on whether the service_name parameters to the basic_resolver_query constructors are allowed to be port numbers (e.g. "80") or whether they have to be symbolic names (e.g. "http"). Port numbers work, at least on Linux, but it's not clear whether this is something that I should be relying on. Similarly for IPv4 and IPv6 addresses in the host_name parameter. Richard Smith

3 2

Guidelines on wiki
by Daniel James 13 Apr '10

13 Apr '10

Hello, I've copied the guidelines onto the wiki now, you can see them at: https://svn.boost.org/trac/boost/wiki/Guidelines/ Any comments? I've changed the beta site to redirect to them. I haven't linked to them from the front page of the wiki as they aren't 'official' yet. I'll be moving more pages over soon-ish. Any ideas about how the wiki should be structured? Daniel

5 10

GSOC 2010 - BGL Graph Connectives.
by Tri Nguyen 12 Apr '10

12 Apr '10

Hi, I am Tri Nguyen from South Plains College. I am interested in Graph Connectives Project of BGL. In this writing, I would like to ask two questions, and then propose my idea of doing four Connectives: union, join, intersection, and difference. My first question is: How big is the graph? Or students will try to do as big as possible. My second question is: What type of data-structures (matrix or list) will be used? I attached my ideas in the PDF file below. Please have a look. I appreciate all responses, Thank you, Tri Nguyen.

4 15

GSoC2010 Sweepline Algorithm
by Andriy Sydorchuk 12 Apr '10

12 Apr '10

Hi, Boost Community! I am interested in participation in GSoC 2010. The project I liked the most is the generic implementation of Sweepline Algorithm. Basically fast and robust Sweepline Algorithm requires implementation of next data structure: 1) Event Queue (priority queue). 2) Sweep Line (self-balancing binary search tree). 3) Output datastructures (voronoi vertices, triangulation edges, etc.). Based on that I got next questions: - Which kind of self-balancing binary trees is better for that kind of approach? I am thinking about Red-Black Trees in prefer to AVL trees, as sweepline algorithm requires more adding and deletion operations. And AVL trees are better for look up operations. - STL library includes two generic implementations of self-balancing binary trees (red-black): map, set. I am quite new with Boost library, but probably there are some more specific self-balancing binary tree implementations there? - For Voronoi diagram and delaunay triangulation input data is set of points. What about input of the Medial Axis problem? -- Best, Andrii Sydorchuk

4 33

[BGL] Revisiting Parallel BGL
by Sandeep Gupta 12 Apr '10

12 Apr '10

Hi, I raised the issue of parallel BFS not working correctly here http://lists.boost.org/boost-build/2009/10/22631.php. The issue remained unresolved. I revisited it for last two days and the incorrectness in likelihood is probably due to initialization of distance property map for all non-start vertex to be infinity. Hope this helps. Thanks Sandeep

3 17

[GSOC] summary of .BigInt library details.
by Ankit Malpani 12 Apr '10

12 Apr '10

hi all, thank you Scott McMurray, Vicente and Bruno for the prompt feedback regarding my proposed BigInt library ideas .(Sorry for the delayed reply as was busy with mid-semester exams.) In general this is what i have gathered from your responses regarding what exactly is being expected by the community from a BigInt library for Boost. 1. frontend based off Boost.Proto 2. backend implemented with the help of Boost libraries like Boost.Math. 3. probably provide two levels of implementations. ( although it would really help if you could weigh the pros and cons of both and eliminate one the the two) 3a. looking at bit-level implementation(less space and probably more execution time) 3b.) digit level manipulation (more space - and probably less execution time). i.e. for an n-digit number is it ok to use up [n/2 to n] bytes of space or necessary to stick to log n amount of space for a BigInt object. my questions are :- 1. Please give your feedback/concerns regarding the above design. 2. Any other libraries like Boost.Math which would help with the backend. -- Ankit Malpani 3rd Year Undergraduate | BE. (Hons) Computer Science BITS Pilani Goa Campus

5 5

[utility/value_init] boost::value_initialized<T> direct-initialized?
by Niels Dekker - address until 2010-10-10 09 Apr '10

09 Apr '10

Can anybody please have a look at the following feature request by Edward Diener? https://svn.boost.org/trac/boost/ticket/3472 He proposed to add an explicit constructor, value_initialized(T const&), to boost::value_initialized<T>. This constructor would copy the value of its argument to the object held by value_initialized<T>. When such a constructor would be added, an object held by value_initialized<T> might no longer be value-initialized. Instead it might be direct-initialized. Does anybody have any moral (?) objections against the idea that value_initialized<T> might hold a non-value-initialized object? Personally I think it would be useful to allow the wrapped object to be direct-initialized. But I do think there's a small risk that the new explicit constructor might cause ambiguities in legacy user code. Therefor I suggested adding an extra "tag" parameter to the new constructor, of a new type, boost::direct_initialized_t: struct direct_initialized_t { }; value_initialized(T const&, direct_initialized_t) Does anyone else also think that's a good idea? Or does anyone prefer the explicit value_initialized(T const&) constructor originally proposed by Edward? See also the thread starting at: "Re: [boost] Transfer of Maintenance Rights (utility/value_init)" http://lists.boost.org/Archives/boost/2010/03/164125.php Kind regards, Niels -- Niels Dekker http://www.xs4all.nl/~nd/dekkerware Scientific programmer at LKEB, Leiden University Medical Center

6 32

GSoC 2010: Heaps and Queues
by Dan Larkin 09 Apr '10

09 Apr '10

I'm another potential student throwing my hat in the ring for the heap project. I'll save most of my personal details for my proposal, but for right now I thought I'd try to get a bit of a dialogue going with the community to help me understand what it is you guys are looking for and what it is I can work towards. So I'll start with my current understanding of the situation. The way I see it, the current heap implementations in boost/pending are rather fractured. They just have simple push/pop interfaces with no mutability (well, there's mutable_heap.hpp, but that's separate and not fleshed out). All in all, what seems to be needed is a standardized heap concept/API along with a few fully-implemented models. Standard heap functionality begs the following functions: - findMin - deleteMin - insert - changeKey - merge These can all be implemented quite efficiently (either worst case or amortized O(logn) time or better) for any heap model. I would be looking to implement the d-ary, binomial, and Fibonacci heaps for sure, with relaxed and Brodal heaps as a possibility, should time allow it. These heap models would be built as extensions of a base Heap class, which could be easily wrapped in a PriorityQueue class which takes the heap-type as a construction parameter (and defaults to a d-ary heap for instance). I know that a stable priority queue was mentioned in earlier discussion, but I'm not sure what to do about that just yet. It'll take a little more thinking before I could say whether I think it'd fall under the scope of the summer project, or if it should be put on the back-burner for later addition to the library. I guess that's basically how I see the problem so far. Please let me know what you think, or what other sort of information/planning/etc. you would like to hear from me prior to my proposal/draft. Dan Larkin

7 34

GSoC Generic Sweep Algorithm
by Sweta Yamini 09 Apr '10

09 Apr '10

Hi, I am writing my proposal for GSoC and I'm interested in writing a generic sweep algorithm. I want to write a generic algorithm which takes in functions to determine the priority of the elements to be considered in the sweep line, and a function to perform necessary computations at each such point. And supplement it with inbuilt functions for line sweep, angular sweep about a point for 2 dimensions and plane sweep for 3 dimensions. Also, implement some algorithms like Voronoi diagrams, Delaunay triangulations, visibility problems using the generic sweep algorithm. I have looked through the documentation and could not find anything related to this. Is there something I have missed? Also, could I contact anyone to discuss? Sweta Yamini Fourth Year Student Department of Computer Science And Engineering Indian Institute of Technology, Kharagpur

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Re: [boost] New Boost.XInt Library, request preliminary review
by Anders Dalvander 08 Apr '10

08 Apr '10

Chad Nelson wrote: > > > This disables the copy-on-write optimization that the library uses by > > > default [...] > > > > > I'm not convinced that integers should be COW. What situations do you > > forsee where COW would be helpful but move semantics wouldn't suffice? > > > As described on the rationale page of the documentation, the primary > reason I'm using copy-on-write is that move semantics aren't widely > available yet. Portability is one of my primary goals, and while I've > seen references to a move-semantics-emulator in Boost, I've also seen > suggestions that it relies on the compiler to somehow recognize it. That > doesn't sound fully portable to me. > No offense, but I'm not confident that COW semantics for the integer class is a wise design choice. I assume you have tested the performance with and without COW semantics, as well tested the performance for thread safe operations with and without COW semantics, before making that decision. Care to disclose the numbers? I guess that you have read the COW string article (http://www.gotw.ca/gotw/045.htm) by Herb Sutter, and his conclusions. Optimizations on other parts should perhaps have been made before converting to COW semantics. Using COW semantics could also complicate the complexity requirements for most functions, as they may be "amortized O(something)" instead of just "O(something)". Another concern I have is that NaN is "signaling" as most operations on a NaN integer will throw an exception. I think it would be more sound if operations on NaN integers would result in NaN integers, compare with float NaN. Don't take these comments the wrong way, I'm very glad to see development of an arbitrary precision integer boost licensed library. Best regards, Anders Dalvander

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