- Boost-users - lists.boost.org

binary archive with text file
by gtsml owevwr 12 Jan '09

12 Jan '09

Hi, I just spend a entire day to realize this code was wrong: std::ofstream ofs(filename.c_str()); boost::archive::binary_oarchive oa(ofs); oa << (*this); And this one was right: std::ofstream ofs(filename.c_str(), std::ios::binary); boost::archive::binary_oarchive oa(ofs); oa << (*this); The consequence of the first code is a "stream_error" throw which doesn't say much about the problem. Instead, an exception should be thrown earlier on if the file is not in binary mode. thanks alot to all the boost contributors, Frank

2 2

Re: [Boost-users] Serialization of forward declared class
by niranjan bangera 12 Jan '09

12 Jan '09

hi all, > i have done in the following way.. even am getting some errors, did i miss > any of the headers, or added extra(added extra for sure). > > Any suggestions will be accepted > > #include <boost/serialization/utility.hpp> > #include <boost/serialization/collection_traits.hpp> > #include <boost/serialization/serialization.hpp> > #include <boost/serialization/base_object.hpp> > #include <fstream> > #include <boost/archive/text_iarchive.hpp> > #include <boost/archive/text_oarchive.hpp> > #include <boost/serialization/assume_abstract.hpp> > > class fd; > > class base: class derived > { > ..... > fd *ptr; > ..... > > friend class boost::serialization::access; > template<class Archive> > void serialize(Archive & ar, const unsigned int file_version) > { > (void) file_version; > ar & ptr; > ar & boost::serialization::base_object<derived>(*this); > > } > > }; //end of class base > > Version::1.36.0 > compliler: g++ 4.1.1.... > > i am getting a error : > error: forward declaration of 'struct fd' > /boost_1_36_0/include/boost-1_36/boost/serialization/access.hpp:109: error: > inva > lid use of undefined type 'struct > > /project/wipro_virtutech_nobackup/users/niranjan/project_new/boost_1_36_0/include/boost-1_36/boost/serialization/extended_type_info_typeid.hpp:117: > note: neither the destructor nor the class-specific operator delete will be > called, even if they are declared when the class is defined. > > Thanks in advance..... >

2 1

Help with a generic algorithm using boost::MultiArray
by Jesse Perla 11 Jan '09

11 Jan '09

Hi:I would like to write an algorithm that operates on a multi-array and am having trouble figuring out how to work with arbitrary numbers of dimensions. A simplified version of my problem that captures all of the types of access I need is: 1) You have a multi-array of (statically defined at compilation) dimensionality N. 2) This data is filled in, but the number of elements in each dimension will frequently be different. 3) Write a function that takes a reference to this multiarray and assigns it the value which is the sum of all of the actual indices(this is contrived, but if I can solve this, I can solve my problem... The key is I need an iterator moving through all dimensions, and I need the index numbers for my calculations). Here is some pseudocode that gives the kind of iterator I would love to have: template<int N> void test_setting(multi_array<double, N>& arr) { //HERE IS PSEUDOCODE: LETS SAY THERE WAS A WAY TO GET AN INDEX THAT YIELDED THE ACTUAL INDEX NUMBERS BUT STILL ACTED AS A POINTER. for(FANCYINDEX = arr.begin(); FANCYINDEX != arr.end(); ++FANCYINDEX) { boost::array<int, N> indicies = FANCYINDEX.get_indices(); //SAY IT RETURNED THE ACTUAL NUMBERS *FANCYINDEX = sum(indicies); //Alternatively, could we go: arr(indicies) = sum(indices); if there is no way for it to be a proper pointer. } } //TO CALL: const int NUMDIMS = 3; //Static at compile time. int n1 = 3; //These might be dynamic. int n2 = 4; int n3 = 5; boost::multi_array<double, NUMDIMS> A(boost::extents[n1][n2][n3]); test_setting(A); Any ideas on how this could be implemented without too much code? Thanks, Jesse

2 1

[proto] iterating array expressions
by Daniel Oberhoff 11 Jan '09

11 Jan '09

Hi, First off: much thanks for previous replies to related problems. One comment: I got told to properly use proto on my array class I needed to separate data from user interface. I found now that it is possible to define expressions non-intrusively without having to change my array structure, but still I understand the motivation, and possibly this way is better anyway. Anhow, now to my new problems. I have now set up proto to be able to evaluate expressions such as: A(_i,_j) + B(_j,_i*_j-2) at a given index (i.e. substituting given numbers for index placeholders _i and _j). Here A and B are of my own n-dimensional array class. Now I would like to iterate such expressions efficiently to evaluate assignment expressions like: C = A(_i,_j) + B(_j,_i*_j-2); efficiently. What I want to do is base it around basic "iterators" for each array indexing expression ( i.e. B(_j,_i*_j-2) and A(_i,_j) in the example) that know how to move to a certain setting for the index placeholders and how to advance along the index placeholders (e.g. advance the data pointer for _i -> _i+1, _j -> _j+1). I think I could implement such iterators (not in the STL sense, since I dont use begin/end, but enough for what I need) for the array indexing expressions, but I dont know how to generate the iterator for the complete expression. I would like such an iterator be generated automatically given the individual iterators for the array indexing expressions and be able to call move, advance, and evaluate on such an iterator. Any hints on where to start before I lose myself deeply in the documents and examples? Any help much appreciated. Best Daniel

2 1

[thread] assertion error in timed_lock
by Ernst Murnleitner 11 Jan '09

11 Jan '09

Hello, Sometimes - especially if I start the program with valgrind - my program exits with /usr/include/boost/thread/pthread/recursive_mutex.hpp:180: bool boost::recursive_timed_mutex::timed_lock(const boost::system_time&): Assertion `!res || res==16' failed. The line 180 is in this function: bool timed_lock(system_time const & abs_time) { struct timespec const timeout=detail::get_timespec(abs_time); int const res=pthread_mutex_timedlock(&m,&timeout); BOOST_ASSERT(!res || res==EBUSY); return !res; } pthread_mutex_timedlock returned ETIMEDOUT. Can the BOOST_ASSERT be changed that it only logs a warning? In a production environment it is not nice, if the program exits. In the man page of pthread_mutex_timedlock I read: ----- ... The pthread_mutex_timedlock() function shall fail if: EINVAL The mutex was created with the protocol attribute having the value PTHREAD_PRIO_PROTECT and the calling thread's priority is higher than the mutex' current priority ceiling. EINVAL The process or thread would have blocked, and the abs_timeout parameter specified a nanoseconds field value less than zero or greater than or equal to 1000 million. ETIMEDOUT The mutex could not be locked before the specified timeout expired. ... ------ Isn't ETIMEDOUT a return value which has to be expected? Greetings, Ernst

2 1

[Spirit] Version question
by Peter Barker 11 Jan '09

11 Jan '09

Hello, I want to use Boost.Spirit to parse some data so I'm reading the documentation. I'm a little confused because the documentation linked to from 1.37.0 takes me to a Spirit user's guide apparently regarding "Spirit classic". Does Boost 1.37.0 include two Spirit versions? If so, do I need to be looking elsewhere for documentation on how to use the non-classic version? Essentially I want to use the latest version of Spirit that comes with Boost 1.37.0 and would like guidance on that please. Regards, Pete

2 3

[mp_math] Wrong sign for mp_int<> after addition.
by Jeroen N. Witmond 11 Jan '09

11 Jan '09

Greetings, I've stumbled across a problem in mp_math in the sandbox, revision 50541. The code below (a Boost.Test test case) demonstrates that the problem is present only for mp_int<> and not for int. The message I get is wrong-value.cpp(16): error in "Mixed_integers<N5boost7mp_math6mp_intISaIvENS0_13mp_int_traitsIjyEEEE>": check j == 4 failed [-4 != 4] Regards, Jeroen. #define BOOST_TEST_DYN_LINK #define BOOST_TEST_MODULE Wrong_sign #include <boost/test/unit_test.hpp> #include <boost/mp_math/mp_int.hpp> #include <boost/mpl/list.hpp> typedef boost::mpl::list< int, boost::mp_math::mp_int<> > test_types; BOOST_AUTO_TEST_CASE_TEMPLATE( Mixed_integers, Type, test_types ) { Type i(-1); BOOST_CHECK_EQUAL(i, -1); Type j = i + 5; BOOST_CHECK_EQUAL(j, 4); // Line 16. }

1 0

[GIL] trouble loading image files
by Kenny Riddile 11 Jan '09

11 Jan '09

This is my first time using GIL and I'm having some difficulty loading jpeg and png files. Here's some code: rgb8_image_t image1; jpeg_read_and_convert_image<rgb8_image_t>( "file.jpg", m_image1 ); rgb8_image_t image2; png_read_and_convert_image<rgb8_image_t>( "file.jpg", m_image2 ); Attempting to load the jpeg causes a crash at jpeg_read_header(&_cinfo,TRUE); in jpeg_io_private.hpp. Attempting to load the png causes a similar crash at png_read_info(_png_ptr, _info_ptr); in png_io_private.hpp. I'm using the libjpeg and libpng builds from these sites: http://gnuwin32.sourceforge.net/packages/jpeg.htm http://gnuwin32.sourceforge.net/packages/libpng.htm

1 1

[datetime] local_date_time and time zone issues
by Boris 10 Jan '09

10 Jan '09

I've been playing with local_date_time and time zones but don't understand the return values of utc_time(), local_time() and local_time_in(). Here's a small program: ---------- #include <boost/date_time/local_time/local_time.hpp> #include <iostream> int main() { boost::local_time::time_zone_ptr tz1(new boost::local_time::posix_time_zone("CET+1")); boost::posix_time::ptime pt1(boost::gregorian::date(2009, 1, 5), boost::posix_time::time_duration(12, 0, 0)); boost::local_time::local_date_time dt1(pt1, tz1); std::cout << dt1.utc_time() << std::endl; std::cout << dt1.local_time() << std::endl; boost::local_time::time_zone_ptr tz2(new boost::local_time::posix_time_zone("CET+2")); std::cout << dt1.local_time_in(tz2) << std::endl; } ---------- The output of this program is: 2009-Jan-05 12:00:00 2009-Jan-05 13:00:00 2009-Jan-05 14:00:00 CET The program uses CET which is the abbreviation for Central European Time which is UTC+1. If the UTC time is now 12:00:00 the local time in CET+1 must be 14:00:00 (and not 13:00:00). Accordingly the local time in CET+2 must be 15:00:00. Why Boost.DateTime appends "CET" to the local time in CET+2 I don't understand either. Is this a bug or do I misunderstand these functions? Boris

3 5

Boost Interprocess condition variables
by Federico Golfrè Andreasi 10 Jan '09

10 Jan '09

Hi! I'm using condition variables of Boost.interprocess 1.36.0 to manage a synchronized access to a shared memory segment by two tasks. I found a problem when: task 1 is waiting on a condition variable and task 2 crashes during his execution, so task 1 waits forever on that variable. How can I kill also task 1? thank you, Federico

3 4