January 2009 - Boost-users - lists.preview.boost.org

[lambda] Does Boost.Lambda support local variables?
by Robert Jones 13 Jan '09

13 Jan '09

If so, can anyone point me at the relevant bit of documentation. If not, are there some 'standard' techniques to produce a similar effect? Many Thanks, Rob.

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class composition
by Hicham Mouline 13 Jan '09

13 Jan '09

hello, There is an example listed in "C++ template metaprogramming" to generate a class with its members from an mpl sequence: template <typename T> struct wrap { typedef T value; }; typedef mpl::vector< type1, type2, type3 > member_types; mpl::inherit_linearly< member_types, mpl::inherit< wrap<_2>, _1 > >::type generated; but then, the generated class did not look like this: class C { type1 t1; type2 t2; type3 t3; }; Can one do that with BOOST_PP and sequences from preprocessor libs instead? regards,

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Can BOOST 1.37 be built without using stlport in Solaris 5.9 Sunstudio 11
by Saibal 13 Jan '09

13 Jan '09

Hi, I am trying to build BOOST without using stlport library, I am getting some errors? Is it possible to build? Have anybody try that earlier? regards, Saibal

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stream error thrown in boost serialization
by Lee MacDonald 13 Jan '09

13 Jan '09

Guys, I'm having a bit of trouble with boost serialisation using boost 1.35 I am writing out my objects to a text file fine. I see the text_oarchive destructor get called and I get the required new line added to the end of the file. However when I read the objects back in, they get created fine, but as the archive reaches the end of file, it throws a stream error. I have tested the example code and that works fine, so I'm stuck at the mo. Unfortunately i can't try writing/reading the objects as binary easily. I presume the archive is trying to read past the end of the stream, but I don't know why as the newline exists? I've tried the following to make sure the stream is good, but archive still throws. while(stream.good()) { archive >> object; } Any help would be appreciated. Thanks. Lee MacDonald Schneider Trading 4th Floor, 25 Copthall Avenue London EC2R 7BP -------------------------------------------------------- Message from: lee.macdonald(a)schneidertrading.com Message to: boost-users(a)lists.boost.org Attached files: 0 This e-mail and any files transmitted with it are confidential, may be legally privileged, and are for the sole use of the intended recipient. Copyright in this e-mail and any accompanying document created by us is owned by us. If you are not the intended recipient of this e-mail or any part of it please telephone our IT Department at the number shown above or by e-mail at info(a)schneidertrading.com. You should not use or disclose to any other person the contents of this e-mail or its attachments (if any), nor take copies. This e-mail is not a representation or warranty and is not intended nor should it be taken to create any legal relations, contractual or otherwise. Schneider Trading Associates Ltd (Registration No. 3692131) is incorporated in England and Wales and the registered office is at 25 Copthall Avenue, London EC2R 7BP. The company is authorised and regulated by the Financial Services Authority

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about delete elements from compressed_matrix
by Peng Wang 13 Jan '09

13 Jan '09

Hi, Dear all, Suppose I want to delete those elements whose values are smaller than 0.5 from compressed_matrix. I have looked for the mailing list but could not find a solution. Could you tell me how I can do this? Thank you very much in advance. Sincerely yours, Wang

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Random Numbers using Boost.
by Atul Kulkarni 13 Jan '09

13 Jan '09

Hi All, I am using boost::random for generating random numbers I am using the default quick start code given up on the web page. I want to generate random numbers between range 1 - n so that they do not repeat themselves for at least n numbers. 1. Is it possible using boost::random? 2. If it is possible what do I need to do except the below code. == boost::mt19937 rng1; boost::uniform_int<> six1(1,30); boost::variate_generator<boost::mt19937&, boost::uniform_int<> > die1(rng1, six1); for(int i=0; i < 29; i++) { cout<<die1()<<endl; } == Thanks in advance. -- Regards, Atul Kulkarni Teaching Assistant, Department of Computer Science, University of Minnesota Duluth Duluth. 55805. www.d.umn.edu/~kulka053

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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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