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

[asio] experience with cygwin
by bnv＠nc.rr.com 16 Mar '09

16 Mar '09

I began porting a cygwin application to boost-1.38 asio this past weekend. So far things are working, and I'm pleased with the simplification of the application code, but a few items have come up... 1. The cygwin documentation only states that the __USE_W32_SOCKETS flag must be defined, but the documentation should also mention that the _WIN32_WINNT flag should be defined (0x0501 for XP) to avoid a warning, and that the ws2_32 and mswsock libraries are needed (at least for XP). 2. The documentation for the ip::tcp::socket object specifies that the cancel() member will "cancel all asynchronous operations associated with the socket". However, when called just before closing the socket, I get an exception along the lines of "operation not supported on this object" (I don't have the exact message in front of me right now). By not calling it, my async handlers are invoked with an error on closing the socket. 3. The application has a signal handler (e.g., SIGINT). However, when the process is inside asio::io_service::run(), the signal handler appears to somehow get suspended and I have to do a "kill -9" rather than just hitting ctrl-c. Is this intentional/expected? Is there a work around, perhaps looping on asio::io_service::run_one()? Thanks, Brian

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Re: [boost] [Math] boost::math::signbit returns false for -NAN
by Hartmut Kaiser 16 Mar '09

16 Mar '09

Ping? Regards Hartmut > -----Original Message----- > From: Hartmut Kaiser [mailto:hartmut.kaiser@gmail.com] > Sent: Wednesday, March 11, 2009 8:35 AM > To: 'boost(a)lists.boost.org' > Cc: 'John Maddock' > Subject: [Math] boost::math::signbit returns false for -NAN > > Hi all, > > the boost::math::signbit function in trunk fails for an argument of - > NAN. > > #include <boost/math/special_functions/sign.hpp> > > int main() > { > using boost::math::signbit; > BOOST_ASSERT(signbit(-std::numeric_limits<double>::quiet_NaN())); > return 0; > } > > I'd expect to get a '1' back, but the function returns zero and the > assertion fails. I know it worked while using Jon Rade's floating point > utilities library from the vault. Does this have been integrated? > > Regards Hartmut >

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[math] Please give me some advice.
by Kasra 15 Mar '09

15 Mar '09

Hi Dongfei, I have downloaded the code and took a good look at it. It is pretty cool. I think the best we could do is to work more on the optimisations (opt.h) to improve the performance. -- Kasra

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[asio and thread] don't play well together under cygwin?
by Brian and Victoria 15 Mar '09

15 Mar '09

Greetings, I have a header file that includes both <boost/thread> and <boost/asio>, which results in the compilation errors below under cygwin. If I take out <boost/thread> then things are fine, except that I need it for my application :) I have "-D__USE_W32_SOCKETS -D_WIN32_WINNT=0x0501" in my compile flags, per the asio documentation. Taking them out appears to resolve the errors below, but causes other errors for asio. Has anyone else run into this problem and found a solution? -Brian In file included from /usr/include/cygwin/sys_time.h:13, from /usr/include/sys/time.h:27, from /usr/local/include/boost-1_38/boost/date_time/c_time.hpp:31, from /usr/local/include/boost-1_38/boost/date_time/microsec_time_clock.hpp:21, from /usr/local/include/boost-1_38/boost/thread/thread_time.hpp:9, from /usr/local/include/boost-1_38/boost/thread/locks.hpp:12, from /usr/local/include/boost-1_38/boost/thread/pthread/mutex.hpp:11, from /usr/local/include/boost-1_38/boost/thread/mutex.hpp:16, from /usr/local/include/boost-1_38/boost/thread/pthread/thread_data.hpp:12, from /usr/local/include/boost-1_38/boost/thread/thread.hpp:17, from /usr/local/include/boost-1_38/boost/thread.hpp:13, from chat.cpp:23: /usr/include/sys/select.h:31: error: `fd_set' has not been declared /usr/include/sys/select.h:31: error: `fd_set' has not been declared /usr/include/sys/select.h:31: error: `fd_set' has not been declared /usr/include/sys/select.h:33: error: `fd_set' has not been declared /usr/include/sys/select.h:33: error: `fd_set' has not been declared /usr/include/sys/select.h:33: error: `fd_set' has not been declared In file included from /usr/local/include/boost-1_38/boost/asio/detail/socket_types.hpp:79, from /usr/local/include/boost-1_38/boost/asio/detail/win_iocp_io_service_fwd.hpp:24, from /usr/local/include/boost-1_38/boost/asio/io_service.hpp:37, from /usr/local/include/boost-1_38/boost/asio/basic_io_object.hpp:20, from /usr/local/include/boost-1_38/boost/asio/basic_socket.hpp:24, from /usr/local/include/boost-1_38/boost/asio/basic_datagram_socket.hpp:25, from /usr/local/include/boost-1_38/boost/asio.hpp:20, from chat.cpp:30: /usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../../include/w32api/winsock2.h:109: error: redefinition of `struct timeval' /usr/include/sys/time.h:16: error: previous definition of `struct timeval' /usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../../include/w32api/winsock2.h:632: error: declaration of C function `int select(int, fd_set*, fd_set*, fd_set*, const timeval*)' conflicts with /usr/include/sys/select.h:31: error: previous declaration `int select(int, int*, int*, int*, timeval*)' here

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[array] remove static qualifier for size(), empty() and max_size() member function
by herve martin 15 Mar '09

15 Mar '09

Hi, I guess that the static qualifier for size(), empty() and max_size() makes the boost::array template class unsuitable for the STL sequence container interface. I recommend to remove the static qualifier. Anyone agrees with me ? best regards, herve

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[array] array_cast helper function
by herve martin 15 Mar '09

15 Mar '09

Hi, I would present here a new helper function which could take place in the boost array package since it is related to C-array. the array_cast() function aims at making cast into C array more friendly than when using the esoteric syntax T(&)[N]. It can help also to check some consistency in size between original type and resulting C array. For some reason reference on C array is almost never used by developers even if a reference on C array encapsulates more information than just a pointer on the 1st element. A striking example is that the dynamic allocation of an array using the new syntax returns a pointer on first element ( int *ptr = new int[10]; ) although I would expect getting a pointer on an array ( int (*ptr)[10] = new int[10]; - this syntax fails but is more conform to what we could expect, even if I must admit that the second syntax is not really intuitive -). array_cast() could make reference on C array more common. The main benefit of array reference is that the size information of the array is encapsulated in the reference type. In the previous 'new' example, when writing { int *ptr = new int[10]; } we have to keep track of the array size by some other way which is not really smart (#define for example). array_cast() use will allow the following syntax: { int (&carray)[10] = array_cast<int>( *new int[10] ); } which is equivalent to: { int (&carray)[10] = *(int(*)[10]) new int[10] ); } Size of the C array can be retrieved just with operation sizeof(carray) In working with array reference rather than with pointer on element array we could imagine some generic algorithm whose implementation could be optimized according to the array size. array_cast() profits also from boost::math::static_gcd function and checks consistency between sizes. for example the following code will raise a static assert since type sizes are not consistent. {{{ struct { char d1; char d2; char d3; } toto; long (&carray)[1] = array_cast<long>( toto ); }}} Indeed, sizeof( toto ) is rarely equal to sizeof( long[1] ). 3 main functions are defined for array_cast(): array<T,N>( INPUT& data) array<T>( INPUT& data) array<N>( INPUT& data) and its derivatives for const, volatile and const volatile lvalues. for more details, take a look at the source code array_cast.hpp<http://www.boostpro.com/vault/index.php?action=downloadfile&filename=array_…>in the boost vault repository and let me know if there is any interest to include it in boost::array. thanks, herve

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Re: [boost] [Boost-users] Maintenace Guidelines wiki page
by vicente.botet 15 Mar '09

15 Mar '09

----- Original Message ----- From: "Tomas Puverle" <Tomas.Puverle(a)morganstanley.com> To: <boost-users(a)lists.boost.org> Sent: Sunday, November 23, 2008 4:31 AM Subject: Re: [Boost-users] Maintenace Guidelines wiki page > >> I have started the Maintenace Guidelines wiki page. >> >> You can access it directly >> https://svn.boost.org/trac/boost/wiki/Guidelines/MaintenanceGuidelines >> >> or via https://svn.boost.org/trac/boost/wiki >> >> Guidelines >> * Maintenance Guidelines >> >> There page need to be completed and surely reworked but this is an starting >> point. >> >> Please be free to improve the page directly or post your comments or > suggestions to this list. >> >> Hopping this goes on the right direction, > > Vincente, > > A few ideas: How will you evaluate that your proposal is actually successful > and being followed by the boost developers? Hi, First this is proposal for guidelines. So people will be after all free to follow some of them or not. I'm expecting from people like you to improve it so it could be followed by more people. > Also, check out Daniel Walker's idea in the Boost.Range thread on boost.devel > about not having the engineers in charge of their own QA. Daniel Walker's idea " Perhaps a procedural solution that could avert this problem in the future is to quarantine the test cases. Authors can maintain commit privileges to their libraries on trunk, but only a select group of independent guardians have commit privileges to the test cases. That way there is a guarantee that libraries pass the same tests from one release to another. If an author would like to make a change that would break a test case, he or she would need to present the change to the list and submit a patch to the test case sentinels. This would be a fairly simple quality assurance protocol: engineers aren't allowed to do their own QA." This is already considered on the guidelines insome way. "Preserve the test from the preceding versions [author] The test from the preceding versions should not be changed when the author modifies its library. These not changed tests are a probe of compatibility with the preceding version. When these test must be changed they indicate a breaking user code issue. So instead of changing them add new ones stating explicitly on which version they were included. Old tests that should fail can be moved to the compile_fail or run_fail tests on the Jamfile. " The Daniel proposal implies some changes in the writing rights of the authors. I prefer to let this point out of these guidelines. Of course I think that this is a good idea. There is another guideline that could be used by the Boost comunity to check the author has not changed the old test cases. "Inspect announced modifications [author, user, RM] The use of the diff file will help to inspect that the modifications introduced have been correctly included on the documentation and a good test coverage has been done. This will result in a non official mini-review of the library. " I will add to check that the old testcases have not been changed. > Finally, please consider the idea of "core" and "new" release cycles, where the > components in "core" have much more stringent requirements on how and when they > are allowed to change. IMO this is out of the scope of the guidelines. Note that at the end it is up to the author to make the modification he/she consider pertinent. Could you send what you have in mind in the form of guidelines? > Finally, do you think it may have been better to start this thread on > boost.devel? I belived that i did it on both. I'm answering to both each time. Should I start a new thread including the guidelines contents? Vicente

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Boost Lite Version
by Jean-Sebastien Stoezel 14 Mar '09

14 Mar '09

Hi, I have been using Boot for desktop applications and I'm very happy with it. It allows me to write portable and reusable code on all the platforms I've been supporting. I also develop C++ applications for small embedded devices, that have very limited ROM and RAM capabilities (several hundreds of kilo bytes of ROM and dozens of kilobytes of RAM). The Boost libraries cannot be used as is for these devices, since the OSes (RTOS I should say) that run on these devices are not supported by Boost. Then my code for these devices is not as portable and reusable as I which it would be. I've developed my own accross-platform generic interface for these devices and it's starting to look like Boost... Except it's not Boost and it's still very proprietary, in the niche sense. I am very interested in having a (real) lite version of Boost for these embedded devices, even if it only consists of stub functions. Is there already an on going effort to do this? Again, the idea is a lite version, something that would fit in less than 30% of the memory of a microcontroller. Jean-Sebastien

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[math] calculate derivative automatically.
by Dongfei Yin 14 Mar '09

14 Mar '09

Hi Bruno, > But I can help you if you want of course.I think the first step for you would be to > learn about Boost.Proto as it's really the tool needed for that. Learn > how to search/replace patterns in an expression. Thank your for your guidance, I am really appreciate your help. I am now going to learn about Boost.Proto. If I have some problem, we can talk about it. Dongfei.

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[geometry] area, length, centroid, behavior
by Barend Gehrels 13 Mar '09

13 Mar '09

I would like to hear the opinion of potential geometry users on the list about the following. For the three geometries, point, linestring (= sequence of points), polygon: What should the generic "area" algorithm return for point and linestring? - 0 (zero) - compiler error (so this function is not defined for them at all) - exception Personally I would feel for 0 (zero) because you can then request the "area" in a generic collection, regardless of what is inside. What should the generic "length" algorithm return for polygon? - 0 (zero) - its perimeter - compiler error - exception What should the generic "centroid" algorithm return for point and linestring? - the point / the average its points - compiler error - exception and for an invalid polygon (e.g. no points at all, or not closed)? - exception - return "false" (if centroid is passed as a reference parameter) - ? (we've not always the compiler error option here because points are usually stored in a runtime collection) Thanks, Barend

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