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boost installation problem
by Bijay Panda 13 Jan '09

13 Jan '09

Hi All, I am trying to install boost 1.34.1 in ubuntu 7.10 by the command below. apt-get install libboost-date-time-dev libboost-date-time1.34.1 libboost-dev libboost-doc libboost-filesystem-dev libboost-filesystem1.34.1 libboost-graph-dev libboost-graph1.34.1 libboost-iostreams-dev libboost-iostreams1.34.1 libboost-program-options-dev libboost-program-options1.34.1 libboost-python-dev libboost-python1.34.1 libboost-regex-dev libboost-regex1.34.1 libboost-signals-dev libboost-signals1.34.1 libboost-test-dev libboost-test1.34.1 libboost-thread-dev libboost-thread1.34.1 It's reading all packages from the related sites during installation but finally it's throwing an error like Internal Error, Could not perform immediate configuration (2) on libc6 Can any one suggest how to get rid of this. -- Thanks & Regards Bijay Kumar Panda Mob-9739591816 bijaykumar.mail(a)gmail.com bijaykumar_panda(a)yahoo.com

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Boost.Parameter: copy constructor gets "mistaken" for constructor(const ArgPack& ) in parent class.
by er 13 Jan '09

13 Jan '09

Hello, I have a situation which I can summarize as: #include <boost/parameter/keyword.hpp> #include <boost/parameter/name.hpp> #include <boost/parameter/parameters.hpp> #include <boost/parameter/preprocessor.hpp> BOOST_PARAMETER_KEYWORD(tag, xx) struct A{ template<typename ArgPack> A(const ArgPack& arg):x_(arg[xx|0]){} A(const A&){} A& operator=(const A& that){ if(&that!=this){ x_ = that.x_; return *this; } } unsigned x_; }; 3 copy constructors are shown below, on the last of which works. However it's really the first one that I'd like to get to work. struct B : public A{ template<typename ArgPack> B(const ArgPack& arg):A(arg){} B& operator=(const B& that){ if(&that!=this){ A::operator=(that); return *this; } } //B(const B& that):A(that){} //no match for 'operator[]' in 'arg[(+<unnamed>::xx)->boost::parameter::keyword<T>::operator| [with Default = int, Tag = tag::xx](((const int&)((const int*)(&0))))]'| //B(const B& that):A(static_cast<A>(that)){} //fails too B(const B& that):A((xx=that.x_)){} //requires knowledge of A's members, not satisfactory. }; Any suggestion, please?

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find substring and substring position
by M 13 Jan '09

13 Jan '09

hello all --------- In: http://www.boost.org/doc/libs/1_37_0/doc/html/string_algo/usage.html#id3676… there is an example: Find Iterator = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = string str1("abc-*-ABC-*-aBc"); // Find all 'abc' substrings (ignoring the case) // Create a find_iterator typedef find_iterator<string::iterator> string_find_iterator; for(string_find_iterator It= make_find_iterator(str1, first_finder("abc", is_iequal())); It!=string_find_iterator(); ++It) { cout << copy_range<std::string>(*It) << endl; } // Output will be: // abc // ABC // aBC = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = how do i find the position of each "abc" in: str1 ? thank's meir

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more Boost::Units questions
by Mark Volkmann 12 Jan '09

12 Jan '09

My biggest issue is that my recent software development experience has involved using Java much more than C++ and I'm trying to learn how to use a C++ library that makes pretty heavy use of templates. Is there a tutorial somewhere that shows examples of doing basic things with this library? The kind of things I'm trying to figure out are: - What is the difference between a "measurement" and a "quantity"? Is it that the former doesn't specify a unit? - Does the library provide functions for converting between different units? ... for example, converting from miles to kilometers. If not, is there a recommended way to do this? - Can I only add quantities that have the same unit or can I add ones with different units and the library will handle conversions for me? - How can I extract the numeric value from a quantity? - How can I extract the unit type from a quantity? Thanks! --- Mark Volkmann

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Help with a generic algorithm using boost::MultiArray/Multiple nested range traversal
by Jesse Perla 12 Jan '09

12 Jan '09

Steven: >int index_of(const multi_array<int, 3>& m, int* iter, int dimension) { > int offset = iter - m.origin(); > return(offset / m.strides()[dimension] % m.shape()[dimension] + >m.index_bases()[dimension]); } Thanks for the code suggestion. Does this code work for N dimensions? it appears to. I would prefer to keep a tight count of the indices in the iterator itself to ensure that we don't need to do this expensive calculation each time, but this looks like a pretty good starting point and would work similarly for my sequential ublas::matrix iteration as well. -Jesse

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Help with a generic algorithm using boost::MultiArray/Multiple nested range traversal
by Jesse Perla 12 Jan '09

12 Jan '09

Hi Rob, Thanks for the response. I also think this is a pretty important use case for this great library. Let me justify why I think an Iterator based approach is the best: * For maximum efficiency (I will be using this in numerical simulations), we will want have an incrementing pointer within the data structure pointing to the actual object, and not just the iterator. * Also, if we have a single forward iterator, then we should be able to reuse a bunch of standard algorithms in the cases where we do not need the actual index values or the order of execution doesn't matter. * In the iterator algorithm, I would love to check the ordering of the data from the template parameters. If it is fortran ordering then we would do the loops in the opposite order for example, and this should be based on querying the data structure in the iterator code. * As for your range based use case, I don't know enough about how iterators and ranges interact to see how that would work. * As to implementation of this, thanks for the pointer to Fusion. This indeed seems to be the best approach since the loops can be generated at compile time, and compilers could then do some very fancy optimization on them. Sadly, I am not a template metaprogrammer, or a very good C++ programmer in general, and am terrified to learn it and lose sight of my non-CS research. Now for the semantics of this, it seems to me that the way the iterator concepts are designed, the distance() function is intended to pass back the related index information. Now my question is whether it is OK for the semantics of distance to pass back a boost::array<NUMDIMS> instead? Seems reasonable to me that it would not be based on passing back a scalar value in this case because that is arbitrarily dependent on the column vs. row ordering. And we can easily generate a boost::array from the distance function by looking at the distance between the .begin() for all of our current positions in the sub-iterators? If the iterator framework was there and the distance implemented as vectors, I can imagine the code looking like: int n1 = 3; int n2 = 4; int n3 = 5; boost::multi_array<double, 3> A(boost::extents[n1][n2][n3]); //NOTE SURE OF THE RIGHT SEMANTICS FOR GETTING AN ITERATOR OUTSIDE OF ONE GENERATED BY THE CONTAINER. multi_array_iterator<double, 3> begin = mult_sequential_iterator_begin(A); multi_array_iterator<double, 3> end = mult_sequential_iterator_end(A); for(mult_sequential_iterator<double, 3> iter = begin; iter != end; ++iter) *iter = f(distance(begin, iter); //POSSIBLE IMPLEMENTATION OF DISTANCE template<int NUMDIMS> boost::array<NUMDIMS> distance(const mult_sequential_iterator& iter1, const mult_sequential_iterator& iter1) const { static_assert(iter1::dimensionality == iter2::dimensionality) boost::array<NUMDIMS> dist; foreach dimension //PSEUDOCODE, FROM FUSION???? array<dimension> = distance(iter1.get_sub_iter<dimension>(), iter2.get_position<dimension>()); //here get_sub_iter returns the sub-iterator stored for that current dimension in the iterator. } template<int NUMDIMS> //HERE THE FUNCTION WOULD BE BASED ON A BOOST::ARRAY. double f(const boost::array<NUMDIMS>& indices) { ...} //AND LETS SAY WE WANTED TO NEGATE THE ENTIRE DATA STRUCTURE, NOW CAN USE STD: int n1 = 3; int n2 = 4; int n3 = 5; boost::multi_array<double, 3> A(boost::extents[n1][n2][n3]); boost::multi_array<double, 3> B(boost::extents[n1][n2][n3]); std::transform(mult_sequential_iterator_begin(A), mult_sequential_iterator_end(A), mult_sequential_iterator_begin(B), negate<double>()); //AND IF WE ADDED THIS ITERATOR TO THE CODE FOR THE MULTDIM: A.begin_sequential() could return the sequential iterator...

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what are the different problems that can occur in network connections and send/recive, what are the related exceptions & errors, and what are the solutions (boost.asio)?
by Saeed Aliakbarian 12 Jan '09

12 Jan '09

While working with boost.asio networking features, in many cases problems may occur due to network connection erros, programmin errors, etc. In each case a different event occurs in the program. Most of the times, and error code is returned or an exception is thrown. I could not find a list of this error causes and their corresponding error codes or exceptions. The only way I could mange only a part of this problem was trough testing, creating a specific error manually, catching the exception or the error code, and the try to manage it in the correct way I suggested myself!!!! If there is not such a page containing my required information, do you agree there is a need for one? Can anyone help me find a better way to do what I am trying to do? Regards Saeed Aliakbarian

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Boost Units standardization?
by Mark Volkmann 12 Jan '09

12 Jan '09

What is the status on getting the Units library to be part of the C++ standard? Is this being pursued? --- Mark Volkmann

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[date_time]utc_to_local crashes
by Jan Deinhard 12 Jan '09

12 Jan '09

Hi, I get a crash calling utc_to_local with dates past 2038-Jan-19 03:14:07. I'm compiling with Visual C++ 2005. using namespace boost; posix_time::ptime pt(gregorian::date(2038, 1, 19), posix_time::hours(3) + posix_time::minutes(14) + posix_time::seconds(8)); date_time::c_local_adjustor<posix_time::ptime>::utc_to_local(pt); Jan

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[Ranges] make_view: when will it be part of a release?
by Christoph Duelli 12 Jan '09

12 Jan '09

I recently had the need to produce from a vector<uint> a string representation (like for IPs) like "23.1.4.742.234.0". I thought that if only those were uints were strings I could boost::join them together. After a bit of searching the internet I found: make_view... very helpful, as indeed operating on iterators and containers only is a bit restrictive. So, first, I'd like to express my thanks for providing such helpful libraries (I love it how Boost.Bind and ASIO fit together, e.g.!). Great job everyone! Is there a better way to get to the string representation hinted to above? What I did is: #include <boost/view.hpp> // not yet part of Boost 1.37 // Helper to convert an uint to a std::string struct Stringer { std::string operator() (unsigned u) const { return boost::lexical_cast<std::string>(u); } }; boost::function<std::string(unsigned)> stringer = Stringer(); // way better than writing the loop by hand! std::string s = boost::join(boost::make_view(data_, stringer), "."); // Does not compile with gcc 4.2.1 // std::string s = boost::join(boost::make_view(data_, Stringer()), "."); Is there some existing class that makes my helper class Stringer unnecessary? (Can I use lexical_cast here w/o a helper class?) Is it possible to avoid putting the functor into a local Boost.Function variable? When will range_ex and make_view() be part of a Boost release? 1.38? (Please?) Best regards, and thank you -- Christoph Duelli

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