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[Interprocess] Possible bug in shared memory on FreeBSD 8.0
by Manish Vachharajani 11 Aug '09

11 Aug '09

I've been happily using Boost.Interprocess to create shared memory regions under FreeBSD 7.2, however, I am having issues on FreeBSD 8.0 pre-release. I can reproduce the problem with Boost 1.39.0 and the svn trunk. The source of the problem appears to be that Boost.Interprocess calls lseek on a file descriptor returned by shm_open, but the results of such an lseek are undefined. Below, I explain further how I came to this conclusion. If you run the program I've appended to the end of this email, the constructor for managed_shared_memory throws an interprocess_exception with error code 29 which is Illegal Seek on FreeBSD. A little bit of system call tracing and debugging reveals that the offending seek is in mapped_region.h:447 (in svn revision 55512). However, digging around, it appears that lseek's behavior on file descriptors for shared memory regions is undefined (See http://www.opengroup.org/onlinepubs/000095399/functions/lseek.html for what IEEE 1003.1 standard has to say about this.) I've confirmed that FreeBSD 7.2 allowed such seeks but 8.0 does not by looking at the kernel source code. For what it's worth AIX 6.1 does not allow such seeks either (see http://publib.boulder.ibm.com/infocenter/systems/index.jsp?topic=/com.ibm.a…) Could someone advise me on what the correct fix for this bug is? I'd be glad to implement it, but I'm not sure what the right fix ought to be. #include <iostream> #include <string> #include <exception> #include <boost/interprocess/managed_shared_memory.hpp> namespace bip = boost::interprocess; int main(const int argc, const char *argv[]) { bool error = true; std::string shmName("testShmRegion"); bip::shared_memory_object::remove(shmName.c_str()); try { std::auto_ptr<bip::managed_shared_memory> segment(new bip::managed_shared_memory(bip::create_only, shmName.c_str(), 12345)); error = false; } catch(const std::exception &e) { std::cerr << "Error: " << e.what() << std::endl; } if(!error) { std::cout << "Shm allocated successfully." << std::endl; } return 0; } Manish

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[asio] very confusing title
by DE 11 Aug '09

11 Aug '09

when i personally see 'asio' i immediately think about steinberg technology asio which stands for 'audio stream i/o' so it's up to you of course just want you to know

4 3

Vault access for Boost.Debug
by Zachary Turner 11 Aug '09

11 Aug '09

Hello, I'd like to request access to the vault. I'm going to upload a proof-of-concept of some of the things I mentioned earlier in my thread about Boost.Debug. This early version gives simple stack traces in limited scenarios, only supports Windows, and isn't designed very well. Here's an example of a program using it in its current form: void test_func(int argc, int argc2, char* argv[]) { stack_trace trace(10); //Maximum depth of 10 levels std::cout << trace.string() << std::endl; } int main(int argc, char* argv[]) { test_func(argc, argc, argv); return 0; } and an example of the stack trace printed as a result of this program: void test_func(int, int, char**) [f:/dev/stack_trace/main.cpp:10] int main(int, char**) [f:/dev/stack_trace/main.cpp:23] int __tmainCRTStartup() [f:/dd/vctools/crt_bld/self_x86/crt/src/crtexe.c:406] int mainCRTStartup() [f:/dd/vctools/crt_bld/self_x86/crt/src/crtexe.c:389] It also currently supports printing the names of all the arguments, but it was hackish and I left it out until it undergoes some redesign. There is currently no documentation, but as this is just a proof of concept I'm currently only looking for people to help out with actual code and/or provide input, so I think that's ok for now. Thanks

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enum / string translation
by Zachary Turner 11 Aug '09

11 Aug '09

I wrote some code to perform both compile-time and runtime translation between enums and their corresponding string values. The only direction that isn't possible is string->enum at compile time. Is there any interest in this? You can use it as follows: typedef enum { ValueA1, ValueA2 } EnumA; typedef enum { ValueB1, ValueB2 } EnumB; BEGIN_ENUM_MAP_DECLS() BEGIN_ENUM_MAP(EnumA, a_map) ENUM_MAP(ValueA1) //maps ValueA1 to the string "ValueA1", provides both compile-time and run-time lookups. ENUM_MAP_NAME(ValueA2, "custom name") //maps ValueA2 to the string "custom name", provides both compile-time and run-time lookups END_ENUM_MAP() BEGIN_ENUM_MAP(EnumB, b_map) ENUM_MAP(ValueB1) ENUM_MAP(ValueB2) END_ENUM_MAP() END_ENUM_MAP_DECLS() void foo() { //value -> string, compile time BOOST_STATIC_ASSERT(enum_map<EnumA>::value_lookup[ValueA2] == "custom name"); //value -> string, runtime EnumB some_value = get_enum_b_from_external_source(); std::cout << "some_value = " << enum_map<EnumB>::name_lookup[some_value] << std::endl; //prints either 'some_value = ValueB1', or 'some_value = ValueB2' //string -> value, runtime EnumA value = enum_map<EnumA>::name_lookup["custom name"]; BOOST_ASSERT(value == ValueA2); } One particularly useful application of this that I've found is with regards to boost::program_options. You can provide an overload of boost::program_options::validate that uses boost::enable_if with boost::is_enum thus providing automatic support for entry of friendly names corresponding to enumerations on the command line or in a config file. Obviously there's many other easily identifiable uses as well. However, this is a common enough problem that I wonder if anyone else has already attempted something like this, and if so maybe I can look at their code first, or just scrap mine altogether and reuse something existing. If not, I'm sure there is plenty of room for improvement in mine but if it could fit somewhere in boost (perhaps boost/utility) I'd be willing to submit it and make necessary improvements. Unfortunately I don't think it's technically possible to have a simple syntax, even through preprocessor magic, that requires you to only specify the name of each enumerated value once, and end up providing both a definition of the enumeration as well as the mapping from string<->value, but if someone comes up with a way that would obviously be ideal.

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[move] moving temporaries of copyable types
by klaus triendl 10 Aug '09

10 Aug '09

Hi, I've recently taken a look at the Boost.Move library and it seems that it is only possible to make 1) either non-copyable types movable or 2) make copyable types move-aware by explicitly moving them. Now, I've discovered for myself that it is possible for pre-c++09 compilers to make copyable types *implicitly* movable by detecting temporaries that can be moved. So, my question is whether this is well-known and this feature was deliberately excluded from Boost.Move or nobody has discovered it yet. It would be great to have support for copy- and (implicit) move-semantics. Klaus Triendl

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[type_traits] is_less_comparable
by Frédéric Bron 10 Aug '09

10 Aug '09

Hi, One year ago, I added to the sandbox the following type_traits: - is_equal_to_comparable, - is_greater_comparable, - is_greater_equal_comparable, - is_less_comparable, - is_less_equal_comparable, - is_not_equal_to_comparable They allow to check if type T can be compared, i.e. if operator==, >, >=, <, <=, !=(T&, T&) exist. At that time, I could not build the documentation so the addition has never been reviewed. I have now a larger hard disk which allows me to have a virtual machine running linux (ubuntu). I would like to check if my documentation addition is OK, therefore could you tell me how I can compile .qbk files? Then, I would like to submit the addition for a review and future inclusion in a boost release; what is the procedure? Regards, Frédéric

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[proto]: rewriting POOMA and Blitz++
by Chandrashekhar Kumar 10 Aug '09

10 Aug '09

Hello, At some time Eric expressed that all the expression template based libraries of boost (notably Phoenix, Spirit) has to be re-written using proto. I think that this target is kind of achieved by now. Can something be done along the similar lines for re-writing the top-notch libraries like POOMA and Blitz++ as a complete examples of proto applications? Does anyone has idea about how huge this undertaking can be? Thanks, Chandra

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"I want everything" should build "out of the box" (on Windows)
by KTC 09 Aug '09

09 Aug '09

Users on Microsoft Windows should be able to build boost with everything, both in terms of all supported variants and all boost libraries, with a single command to bjam assuming they have all the optional supporting libraries available. An user download boost, and want to build all the libraries that require building go read the Getting Started Guide <.../getting_started/windows.html#invoke-bjam> and see the after getting bjam they use the command bjam --build-dir=build-directory toolset=toolset-name --build-type=complete stage So they enter that into the command prompt and see lots of warnings and notes about missing optional components. The warnings and notes itself is fine and informative. Actually, it's incomplete as it stand as it doesn't tell the user about Boost.IOStreams optional component requirement of bzip2 & zlib headers. Okay, the user go and install all the optional components the warnings and notes tell them. After installing Python, ICU (building it first), Expat (building it first), and MPI (say MS-MPI), they try again. This time with the command becoming bjam --toolset=... --build-dir=... --build-type=complete -sHAVE_ICU=1 -sICU_PATH="..." -sEXPAT_INCLUDE="..." -sEXPAT_LIBPATH="..." -sBZIP2_SOURCE="..." -sZLIB_SOURCE="..." stage Nope, MPI requires modification of user-config.jam or building it on its own with --with-mpi. Why? No other optional components build that way. So they look to see how they do that, and does it. Second attempt and ... nope. New to 1.39 is the errors error: link=shared together with runtime-link=static is not allowed error: such property combination is either impossible error: or too dangerious to be of any use due to the changes made as a result of <http://lists.boost.org/Archives/boost/2009/04/150675.php>. (Recently noted on <http://groups.google.com/group/boost-list/browse_thread/thread/2a7bd07468b5…>.) While catching those errors is good, maybe it should be fixed as well such that it doesn't come up in the first place if someone do a --build-type=complete with ICU. So now the users have to build Boost.Regex separately from the rest of the library (after finding how to pass the link= & runtime-link= options). By the way, at this point I would like to point out how it's strange that -sHAVE_ICU=1 mean to build with ICU, but so is -sHAVE_ICU=0 .... :S And ... nope, even separately Boost.Regex still wouldn't build without errors. No one told them they need to rename icuin.lib, icuind.lib, icuind.pdb & icudt.lib from ICU to icui18n.lib, icui18nd.lib, icui18nd.pdb & icudata.lib respectively. With Boost.Regex built, we turn to the rest of the library with --without-regex. After waiting a while, we discover ... nope, Most of the library is built but not Boost.Graph. Sorry, this time no one told them they need to change Boost.Graph's Jamfile.v2 file with "<find-shared-library>expat" to "<find-shared-library>libexpatwMT" and adding "<define>XML_STATIC". Boost is great, it's free, it's flexible and I understand it's developed for free by volunteers, but its "installation" for someone that want every libraries could be improved. :-) Regards, KTC -- Only two things are infinite, the Universe and Stupidity. And I'm not quite sure about the former. - Albert Einstein

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[Interprocess::Semaphore] Deadlock on more producers - one consumer problem
by Cosimo Calabrese 09 Aug '09

09 Aug '09

Hi to all, I've a buffer of 10 positions; 4 producers put elements on the buffer and only 1 consumer pick them; the producers generate elements very fastly, but the consumer picks the element very slowly. I've decided to synchronize the producers and the consumer with a boost::interprocess semaphore initialized to 10. Before to put an element in the buffer, the producer execute a wait() in the semaphore; the 4 producers put quickly 10 elements in the buffer, so they all block on the wait(). When the consumer picks an element from the buffer, it performs a post() on the semaphore. Here is the problem: the post() unlocks only one of the 4 producers. Consider this scenario: - the producers are all in wait state; the semaphore counter is 0; - the consumer picks an element and perform a post(), that unlocked the producer_1; the semaphore counter is 1; - the producer_1 is unlocked but it doesn't produce any element; the other producers are locked; - the consumer picks the other 9 elements in the buffer and perform the 9 post() on the semaphore, but the semaphore counter becomes 2, 3, 4, ... 10, and so the semaphore doesn't signal the other producers, that remains in lock state(). --> DEADLOCK. Is there a way to unlock all the producers with the boost::interprocess::semaphore? Or I have mistaken the approach of the problem? Thanks to all, Cosimo Calabrese.

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backward binary compatibility of boost shared libraries
by Андрей Пономаренко 08 Aug '09

08 Aug '09

Hello, I'm from Institute for System Programming of Russian Academy of Sciences and we are developing a free lightweight tool for checking backward/forward binary compatibility of shared C/C++ libraries in OS Linux. It checks interface signatures and data type definitions in two library versions (headers and shared objects) and searches ABI changes that may lead to incompatibility. We have released 1.2 version of this tool and we'd like you to consider its usefulness for your project. The wiki-page with the latest release of binary compatibility checker is http://ispras.linux-foundation.org/index.php/ABI_compliance_checker Andrey Ponomarenko

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boost 1.40.0 release date?
by Zoran Cvetkov 08 Aug '09

08 Aug '09

I would like to know when is scheduled release date for version 1.40 of boos library? Some critical fixes are in there and I'd like to know when we should expect it? Browsing the web site didn't help me, did I missed something? Thanks in advance!

2 1

[1.40] timeline?
by John Maddock 07 Aug '09

07 Aug '09

Do we have a revised timeline for 1.40 yet? I'm asking because the regex lib is ready for a substantial update (provided trunk tests cycle OK obviously!). Thanks, John.

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[BGL] How to stopping prematurely a graph exploration
by Cosimo Calabrese 07 Aug '09

07 Aug '09

Hi to all, I'm searching for a good method to stopping prematurely a graph exploration, e.g. when I've just founded and explored a particular vertex. I think I've to create a visitor to which passing the particular vertex, but I don't know how to configure it. A very brutal method is to wrap the exploration function in a try-catch block, and then throw an exception in the examine_vertex funtion. I want to believe that there's a more elegant method than this... Best regards, Cosimo Calabrese.

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[config] symbols export from shared library (#2114)
by Alexander Arhipenko 07 Aug '09

07 Aug '09

Guys, I've decided to start a new thread on this topic. The messages beyond was taken from the last ticket comments. >--------------------------------------------------------------------- >*** Changed 19 hours ago by johnmaddock *** >--------------------------------------------------------------------- > >Is this nearly ready to go in Trunk now? > >Before it does at the very least we need: > >1) An update for http://www.boost.org/development/separate_compilation.html >2) An update for the Boost.Config docs for each of these new macros. >3) A clear understanding of what BOOST_SYMBOL_FORWARD_EXPORT/IMPORT do. >4) A clear understanding of what needs re-exporting - >IMO BOOST_EXCEPTION_EXPORT is somewhat misleading since as I understand the gcc docs >this may need to be applied to any class that has "vague linkage" whatever that is. >Also do we need to re-export std lib exceptions from our SO's? >Do we have a dependency analysis to know when we need to use these (or that we don't need to)? > >John. > >----------------------------------------------------------------- >*** Changed 3 hours ago by arhipjan@… *** >----------------------------------------------------------------- > >Replying to johnmaddock: > >JFYI, stdcxx library (at least of version 4.1.1 and later) >already have default visibility for std::exception, std::bad_exception, i.e: > >//exception header > >#pragma GCC visibility push(default) > >namespace std { > > class exception {/*...*/}; > class bad_exception {/*...*/}; > >//... > >Also logic_error, runtime_error don't cause abnormal program termination >since they have key functions >(i.e. at least one non-inline virtual function). >--------------------------------------------------------------------- >*** Changed 26 minutes ago by anonymous *** >--------------------------------------------------------------------- > >I forgot one other requirement: we should maybe try and put together a small test case to check that this all works. > >Good to hear that libstdc++ already does the necessary work, does this mean that exceptions that inherit from std::runtime_error (as I think all Boost >exceptions do?) are automatically visable and don't need re-exporting on account of their virtual functions? > >Oops, one other thing (sorry!), how if at all is Boost.Exception effected by this - especially as it's header only? > >Cheers, John. I would like to make some comments: 1) BOOST_EXCEPTION_EXPORT macro In current patch version there is no need for this macro, since all the symbols marked with BOOST_SYMBOL_EXPORT always have default visibility on gcc. (In the original version, they have default visibility when building shared library and hidden visibility when using it in another shared library). 2) >>>>Also do we need to re-export std lib exceptions from our SO's? >>JFYI, stdcxx library (at least of version 4.1.1 and later) >>already have default visibility for std::exception, std::bad_exception >>[snip] >>Also logic_error, runtime_error don't cause abnormal program termination >>since they have key functions >>(i.e. at least one non-inline virtual function). >Good to hear that libstdc++ already does the necessary work, >does this mean that exceptions that inherit from std::runtime_error (as I think all Boost exceptions do?) >are automatically visable and don't need re-exporting on account of their virtual functions? The exceptions that inherit std::exception (or std::runtime_error) are not visible. But throwing such exception from shared library and catching it in another exe or lib doesn't cause abnormal termination (but only if thrown exception have at least one key function)

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Re: [boost] Using channel with boost 1.39.0
by Yigong Liu 07 Aug '09

07 Aug '09

Hello Joaquim, Thanks for your help. I'll soon fix these issues with a new update to vault. Best Regards. Yigong > > However in some samples has appeared warnning about deprecated casts > to transfrom from std::string to char*. I attach to this e-mail the > output of compilation of samples to fix the warnings. > > Thanks and Best Regards, > Joaquim Duran > >

1 0

Boost.Plot? - Scalable Vector Graphics
by Paul A. Bristow 07 Aug '09

07 Aug '09

Jake Voytko started this library during a 2007 GSoC and I have now expanded it quite a bit, and begun to use it for my own purposes (including preparing the plot for the Boost.Math library functions and statistical distributions). Before I do any more work on it, I'd appreciate feedback from Boosters on how useful they think it might be, perhaps as a Boost library? Although it still has plenty of wrinklies (the calculation of positioning of titles, legends, axes labels and ticks labels is intricate - to say the least). And there are not-a-few nasty warts (this may be the 1st version to throw away?), so it is in no way review-ready. But I believe it is working well enough for you to try to use it - and to give me feedback. There are of course hundreds of programs for plotting. What is special about *this* library is that it is in C++ and it has a Boost license. It allows you to add just a few lines of code to the end of your C++ program to take data from any STL container (all or part) and produce a plot as a Scale Vector Graph (.svg) file. (No need to export data to a file and suck into Excel ;-) Applause!) .svg files can be displayed by all good Internet Browsers (and even by IE8 with an Adobe add-in). They are very small but high quality, highly zip compressible, and equally suitable for printing to viewing on mobiles (only the features of Tiny SVG are used.). It takes as little code as svg_2d_plot my_plot; my_plot .plot(map1, "Series 1").stroke_color(blue) .plot(map2, "Series 2").stroke_color(red") .autoscale(map1); my_plot.write("./2d_simple.svg"); but you can have hours of fun trying out hundreds of options to produce some rather fancy plots. For your amusement, attached are a few (mostly contrived) examples (with tasteless garish colors just to highlight the possible options). There are also lots and lots of other examples. (Note that the 20 plots occupy a mere 30 kb when zipped). Unusually, there is lots (too much? - 6Mbyte hyperlinked and indexed PDF!) of documentation, produced using the C++ in QuickBook with Doxygen reference info and John Maddock's auto-indexing. But there are hundreds of options, so you will need all the help you can get from tutorials, examples and indexes. A novel feature is the built-in handling of an 'uncertain' type (based on Evan Marshal Manning, C/C++ Users Journal, March 1996 page 29 to 38) including a double 'most likely' value, an 'uncertainty' estimate, roughly standard deviation, and an estimate of 'degrees of freedom'. This can be used to display confidence ellipses and label values "1.23 +-0.01 (21)", for example. (Of course, you can make much better confidence estimates using the Boost.Math library). You can view and can get code from the Boost sandbox https://svn.boost.org/svn/boost/sandbox/SOC/2007/visualization Docs are available to build as html and pre-built as pdf (patience - 6 Mbyte!) https://svn.boost.org/svn/boost/sandbox/SOC/2007/visualization/libs/svg_plot /doc/pdf/svg_plot.pdf or http://tinyurl.com/coqlbg (or ask if you want zips instead). Paul PS Thanks to all those who have offered support, especially John Maddock of course. It has stress-tested the Quickbook - Doxygen indexing system ;-) I haven't managed to make the index work perfectly yet and I'm sure it can be improved. PPS If I were doing this again, I would not use 'derived' trick to permit re-use of functions by 1D, 2D and boxplots - it causes the Intellisense of MS VisualStudio IDE 'Intelligence Circuits' to melt (and sometimes crash - workaround - delete the .ncb file) making the nice 'goto definition' feature ineffective and makes debugging difficult (as does the use of set and get functions). I suspect it makes compile times longer too. There must be a better way - suggestions welcome. But I *would* use the chaining feature - I think it makes a very nice syntax for the user - but tell me what you think. --- Paul A. Bristow Prizet Farmhouse Kendal, UK LA8 8AB +44 1539 561830, mobile +44 7714330204 pbristow(a)hetp.u-net.com

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[Boost.Thread][Boost1.39]:boost::thread& is not accessible from boost::move
by Karun Gahlawat 07 Aug '09

07 Aug '09

Running CC 5.10 to build Boost.Thread using the following command: Referred to this list by boost-build Trying to build Boost.Thread using Sun CC 5.10 on opensolaris. This one looks like a generic error. "CC" +d -library=stlport4 -g -mt -m64 -KPIC -DBOOST_ALL_NO_LIB=1 -DBOOST_THREAD_BUILD_DLL=1 -DBOOST_THREAD_POSIX -I"." -c -o "/tmp/boost/boost/bin.v2/libs/thread/build/sun/debug/a ddress-model-64/stdlib-sun-stlport/threading-multi/pthread/thread.o" "libs/thread/src/pthread/thread.cpp" Getting this error: "./boost/thread/detail/thread.hpp", line 344: Error: boost::thread::thread(boost::thread&) is not accessible from boost::move(boost::detail::thread_move_t<boost::thread>). 1 Error(s) detected. -- Karun -

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[function_types] documentation issues
by Sam Partington 06 Aug '09

06 Aug '09

Hi all, I am writing a library that aims to make using dynamic libraries easier across platforms. The aim is the following : dynamic::library lib("sharedlib.so"); dynamic::function<int (int, int> fn(lib, "fn"); int result = fn(1, 2); So to achieve this I needed to implement forwarding functions and I used function_types to make this easier. This all worked fairly well, but in general I really struggled with figuring out how to use function_types. Though simple uses were fairly straight forward, as soon as I came across a STDCALL function it all fell over and I got compiler errors "'value' : is not a member of 'boost::function_types::function_arity<T>". I have managed to fix it, but the route there was far from obvious, and I would put that entirely down to incomplete and misleading documentation. Eventually, I found the Reference->Macros section which discussed calling conventions : BOOST_FT_CC_* Enables a specific calling convention. * dentoes the macro suffix, as defined by BOOST_FT_CC_NAMES or BOOST_FT_BUILTIN_CC_NAMES. The macro expands to a list of restrictions, separated by the | character. Possible items are: callable_builtin member non_member variadic non_variadic If no such macro is defined for a particular calling convention, it is disabled. Example: #define BOOST_FT_CC_STDCALL non_variadic|callable_builtin // enables stdcall calling convention for all non-variadic, // callable, builtin types Ahah! It looked like I needed to #define BOOST_FT_CC_STDCALL non_variadic|callable_builtin, as per the example there. However this caused monstrous compile errors from the guts of function_types initially stating that "'...' requires cdecl". Further reading pointed me to this : BOOST_FT_COMMON_X86_CCs Defining this macro causes the following macros to be defined, if not defined already: #define BOOST_FT_CC_CDECL BOOST_FT_COMMON_X86_CCs #define BOOST_FT_CC_STDCALL non_variadic|BOOST_FT_COMMON_X86_CCs #define BOOST_FT_CC_FASTCALL non_variadic|BOOST_FT_COMMON_X86_CCs So I added the following : #define BOOST_FT_COMMON_X86_CCs But this also failed with more bizarre errors, eventually I experimented with : #define BOOST_FT_COMMON_X86_CCs 1 Which finally worked. But the docs do not indicate that you need to define it with any particular value. The whole problem would have been so much simpler if there was one of more of the following sections in the documentation : "Getting Started", "Calling Conventions", "Common Pitfalls", or an FAQ. Sam

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[program_options] Can this library write config file?
by Guanqiang Liu 06 Aug '09

06 Aug '09

the boost::program_options can read options from config file. But, can this library write opions into config file?

3 2

[BGL] To customize the graph traversing
by Cosimo Calabrese 06 Aug '09

06 Aug '09

Hi to all, I'm studying the BGL, and I've a question. I've noticed that: - the traversing algorithms, like breadth first search, only decide how to traverse the graph, but do not perform specific calculations; - if I want to perform any calculation during the traverse, I can do it passing a custom visitor to the algorithm. But the question is: how can I customize the traverse method? The algorithms always explore enterely the graph. EXAMPLE: every edge (u, v) of a graph have a property "edge_can_traverse_t" that says on which of adjacent edges starting from v I can continue the traverse. _C _F o| /| o / o / A---->B---->D o o o >G \ \ \ \ _\| _\| E H ----------------------------------------- | edge | property edge_can_traverse_t | | | (vector<edge>) | ----------------------------------------- | (A,B) | (B,D) , (B,E) | | (B,C) | empty | | (B,D) | (D,F) , (D,H) | | (B,E) | empty | | (D,F) | empty | | (D,G) | empty | | (D,H) | empty | ----------------------------------------- For example, if I come from the (A,B) edge, I want that the algorithm consider only the (B,D) and (B,E) edge, and skip the (B,C) edge. The solution I found is to modify the breadth_first_search algorithm, adding a predicate to the visitor and performing a control when the algorithm examines the outer edges of the current vertex. Something like this: //============================================================================== // PREDICATE (in the visitor) //============================================================================== template <class IncidenceGraph, class PredecessorMap> bool can_traverse_edge( edge_descriptor e, IncidenceGraph &g, PredecessorMap p ) { typedef graph_traits<IncidenceGraph>::vertex_descriptor VertexDescriptor; VertexDescriptor u = source( e, g ); // select the source of the edge EdgeDescriptor eFrom = edge( p(u), u ); // select the previous visited edge if ( e is contained in the edge_can_traverse_t property of eFrom ) return true; else return false; } //------------------------------------------------------------------------------ //============================================================================== // breadth_first_visit //============================================================================== template <class IncidenceGraph, class Buffer, class BFSVisitor, class ColorMap> void customized_breadth_first_visit (const IncidenceGraph& g, typename graph_traits<IncidenceGraph>::vertex_descriptor s, Buffer& Q, BFSVisitor vis, ColorMap color) { [.....] put(color, s, Color::gray()); vis.discover_vertex(s, g); Q.push(s); while (! Q.empty()) { Vertex u = Q.top(); Q.pop(); vis.examine_vertex(u, g); for (tie(ei, ei_end) = out_edges(u, g); ei != ei_end; ++ei) { if ( !vis.can_traverse_edge( *ei ) ) continue; [.....] } //------------------------------------------------------------------------------ Does it exist a better mechanism to control the traverse with the BGL? Or I must implement my solution? Best Regards, Cosimo Calabrese.

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Re: [boost] Using channel with boost 1.39.0
by Yigong Liu 06 Aug '09

06 Aug '09

Hello, this early morning i uploaded a new version of "Channel" to Vault ( http://www.boostpro.com/vault/index.php?&direction=0&order=&directory=Distr…) which is updated to build with latest boost distribution (1.39) and the following compilers: ubuntu8.04/g++4.2.4, ubuntu9.04/g++4.3.3, windows(VC++2005, VC++2008). I haven't yet got chance to install fedora11 to try out. Joaquim, could you please help give the new version a try? Channel is a distributed message passing framework built on top of boost. ( http://channel.sourceforge.net) Regards Yigong I'm trying to run the channel examples compiled with boost trunk > version with the last released channel version 0.07.1. In gui_event > and in ping-pong examples, there are errors at compilation (I've not > tested more examples). I'm using gcc 4.4.0 from Fedora 11. Which is > the exepected version of boost to test the channel ? > > Joaquim >

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Partial Sort and Partition with Ranges [was: Boostcon Keynote available]
by Scott McMurray 05 Aug '09

05 Aug '09

2009/8/3 Marshall Clow <mclow.lists(a)gmail.com>: > at http://boostcon.blip.tv > > Thank you, everyone, for your patience. > More videos from Boostcon will be going up there in the near future. > Thanks, Marshall, I'd been looking forward to that. I see that the talk presents a two-range form of partialSort, which I don't see in D's standard library[1]. Does anyone know the history there? On a related note, how would I, using ranges, sort only the first half of a partition? It appears I can only get a range for the second half[2]. In code, I'm looking for the equivalent of sort(b, partition(b, e, pred)); [1] http://www.digitalmars.com/d/2.0/phobos/std_algorithm.html#partialSort [2] http://www.digitalmars.com/d/2.0/phobos/std_algorithm.html#partition

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[1.40.0] Beta planned for this weekend
by Beman Dawes 05 Aug '09

05 Aug '09

I'm planning to put together the 1.40.0 beta this weekend. Please ask permission before updating branches/release. Thanks, --Beman

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Important: Boost server downtime on August 5, 2009
by Doug Gregor 05 Aug '09

05 Aug '09

The Boost mailing lists, web server, and Subversion server will be offline tomorrow (Wednesday, August 5th) from 8:00AM EDT to 9:00AM EDT while we upgrade the mailman software. My apologies for the late notice. - Doug

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Boostcon Keynote (finally!) available.
by Marshall Clow 05 Aug '09

05 Aug '09

at http://boostcon.blip.tv Thank you, everyone, for your patience. More videos from Boostcon will be going up there in the near future. -- Marshall

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