October 2006 - Boost-users - lists.preview.boost.org

Enforcing CRTP with the MPL?
by Stefan Schild 09 Oct '06

09 Oct '06

Hi there Having a templatized base class B template<class T> class B ..... is it possible to enforce that a class D can derive from B IF AND ONLY IF the curiously recurring template pattern is applied, that is class D1 : public B<D1> ... // ok, compile class D2 : public B<X> ... // not ok, do not compile ??? Thx Stefan

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[boost] Review of Generic Image Library (GIL) begins today, Oct5, 2006
by Tom Brinkman 09 Oct '06

09 Oct '06

The review of Generic Image Library (GIL) begins today, October 5, 2006, and continues through October 15, 2006. Please download the library at: http://opensource.adobe.com/gil. Minor change are being made regularly (daily), so check the site often for updates. I highly recommend viewing the 55 minute Breeze presentation describing the library at: http://opensource.adobe.com/gil/presentation/index.htm A tutorial is available at: http://opensource.adobe.com/gil/gil_tutorial.pdf A design guide is availage at: http://opensource.adobe.com/gil/gil_design_guide.pdf Description: The Generic Image Library (GIL) is a C++ library that abstracts the image representation from operations on images. It allows for writing the image processing algorithm once and having it work for images in any color space, channel depth and pixel organization, or even synthetic images, without compromising the performance. GIL has an extension mechanism that allows for adding extra functionality. Two extensions are currently provided – one for image I/O and one for handling images whose properties are specified at run-time. Review questions: Please always explicitly state in your review, whether you think the library should be accepted into Boost. You might want to comment on the following questions: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? - Are you knowledgeable about the problem domain? Tom Brinkman _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/ listinfo.cgi/boost

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access to boost spars matrix values
by Franck Perignon 09 Oct '06

09 Oct '06

Good morning, Can somebody help me using sparse matrices? Here is my problem: I have a class, named MySimpleMatrix, whith a private member, mat, of type MyMat which is a union of various boost matrices type: typedef matrix<double, row_major,std::vector<double> > DenseMat; typedef triangular_matrix<double, upper, row_major, std::vector<double> > TriangMat; ... typedef mapped_matrix<double> SparseMat; ... union MyMat{ DenseMat *Dense; TriangMat *Triang; SymMat *Sym; SparseMat *Sparse; BandedMat *Banded; }; class MySimpleMatrix { private: unsigned int num; MyMat mat; ... } num =1, means mat is a dense, 2 a triangular and so on. the operator () is overloaded in the following way: double& MySimpleMatrix::operator () (unsigned int row, unsigned int col) { ... switch(num){ case 1: return (*mat.Dense)(row,col); break; ... case 4: return (*mat.Sparse)(row,col); break; ... } } It works for all matrices types, except sparse where it fails with this message: error: invalid initialization of non-const reference of type 'double&' from a temporary of type 'boost::numeric::ublas::sparse_matrix_element<boost::numeric::ublas::mapped_matrix<double, boost::numeric::ublas::basic_row_major<unsigned int, int>, boost::numeric::ublas::map_std<unsigned int, double, std::allocator<std::pair<const unsigned int, double> > > > >' I undersand I need to get a reference to double as a return value, which is not given by (*mat.Sparse)(row,col), and thus my question is how to get the good type from mat.sparse to make my operator work?? Thanks, F.Perignon

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boost::regex locale problem
by boost＠larroy.com 09 Oct '06

09 Oct '06

Hi, I'm having a lot of trouble with boost::regexp and locales, even trying to change it makes the program fail. Can anybody help? #include <iostream> #include <string> #include <cstdlib> #include <cassert> #include <vector> #include <stdexcept> #include <locale> #include <boost/regex.hpp> using namespace std; using namespace boost; int main(int argc, char *argv[]) { string regexp, text; if( argc != 3 ) { exit(EXIT_FAILURE); } else { regexp = argv[1]; text = argv[2]; } cout << "regexp: " << regexp << endl; cout << "text: " << text << endl; regex re(regexp,regex_constants::perl); re.imbue(locale("es_ES.UTF-8")); smatch match; if(regex_match(text, match, re)) { cout << "MATCH" << endl; for(smatch::const_iterator i = match.begin(); i != match.end(); ++i) { cout << i->str() << endl; } } else { cout << "NO match" << endl; } } ./testre '\w' "é" Program terminated with signal 8, Arithmetic exception. #0 0xb7ea0883 in boost::re_detail::perl_matcher<__gnu_cxx::__normal_iterator<char const*, std::string>, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::string> > >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::construct_init () from /usr/lib/libboost_regex-gcc-mt-1_33_1.so.1.33.1 (gdb) bt #0 0xb7ea0883 in boost::re_detail::perl_matcher<__gnu_cxx::__normal_iterator<char const*, std::string>, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::string> > >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::construct_init () from /usr/lib/libboost_regex-gcc-mt-1_33_1.so.1.33.1 #1 0x08049ea9 in perl_matcher (this=0xbf806c24, first={_M_current = 0x804c02c "é"}, end= {_M_current = 0x804c02d ""}, what=@0xbf806d20, e=@0xbf806d3c, f=boost::regex_constants::match_default, b={_M_current = 0x804c02c "é"}) at /usr/include/boost/regex/v4/perl_matcher_common.hpp:44 #2 0x08049f27 in boost::regex_match<__gnu_cxx::__normal_iterator<char const*, std::string>, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::string> > >, char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > (first= {_M_current = 0x804c02c "é"}, last={_M_current = 0x804c02d ""}, m=@0xbf806d20, e=@0xbf806d3c, flags=boost::regex_constants::match_default) at /usr/include/boost/regex/v4/regex_match.hpp:42 #3 0x08049fd3 in boost::regex_match<std::char_traits<char>, std::allocator<char>, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::string> > >, char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > (s=@0xbf806d44, m=@0xbf806d20, e=@0xbf806d3c, flags=boost::regex_constants::match_default) at /usr/include/boost/regex/v4/regex_match.hpp:75 #4 0x0804926b in main (argc=3, argv=0xbf806df4) at testre.cpp:25 -- Pedro Larroy Tovar, pedro at larroy dot com | http://pedro.larroy.com/ * Las patentes de programación son nocivas para la innovación * http://proinnova.hispalinux.es/

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Interest in undo/redo framework
by Benjamin Lau 09 Oct '06

09 Oct '06

Hello all, I'd just like to make a general survey over whether or not anyone has or has had any interest in an undo/redo framework? Similar in scope to what the Qt Undo Framework (http://doc.trolltech.com/4.2/qundo.html) hopes to achieve? Benjamin Lau

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[Parameter] Adding arguments to pack through macro?
by Johan Nilsson 09 Oct '06

09 Oct '06

Hi, I guess that the subject line isn't even technically correct. What I'd like to do is to implement something like the following: #define FOO(x) MyNamedParamFn(x, d = 3, e = 4) Where e.g. "FOO((a = 0, b = 1));" would expand to the equivalent of: MyNamedParamFn(a = 0, b= 1, d = 3, e = 4); Is this possible? / Johan

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Re: [Boost-users] [Thread] destructor called several times
by elconio＠commonworld.info 07 Oct '06

07 Oct '06

Hi, thanks for the explanations and the quick answer ! Conio.

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[Thread] destructor called several times
by elconio＠commonworld.info 07 Oct '06

07 Oct '06

Hello, I am using boost::thread for a program, but it behaved in an unexpected way (to me at least). I extracted a small case that shows my problem. I searched in the archives and in the docs, but I couldn't figure this out. With the following code [1] I expect the constructor of my the class MyThread to be called only once and yet on my machine it is called 11 times! [2] The problem is that I was freeing some ressources from the destructor and that even before the operator() was called sometimes. I am using the CVS version from 3 days ago on a linux x86. Thanks for any help or any pointer ! [1]: #include <iostream> #include <boost/thread/thread.hpp> class MyThread { public: MyThread () { std::cerr << "Constructor called.\n"; } ~MyThread() { std::cerr << "Destructor called " << (++id) << ".\n"; } void operator()() { std::cerr << "Operator() called.\n"; } private: static int id; }; int MyThread::id = 0; int main() { MyThread * pt = new MyThread(); boost::thread th( *pt ); th.join(); std::cerr << "\nEnd\n"; delete pt; } [2] Constructor called. Destructor called 1. Destructor called 2. Destructor called 3. Destructor called 4. Destructor called 5. Destructor called 6. Destructor called 7. Destructor called 8. Destructor called 9. Operator() called. Destructor called 10. End Destructor called 11. -- Conio.

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[review-results] pimpl_ptr
by Rene Rivera 07 Oct '06

07 Oct '06

Unfortunately I must say that the pimpl_ptr library will not be part of Boost at this time. The results where decidedly against the library in the proposed form. A few points about the library where clear: * Many want to see a pimpl_ptr in Boost. * The proposed design was considered to not do enough towards addressing the handle-body idiom within C++. * Some of the ideas, the policies, where both liked and disliked. Which raised the specter of the lack of a policy pointer. Hopefully we will see this idiom addressed in some near future. Last, I must apologize for the late results. But I must thank Ronald for the gentle prodding :-) -- -- Grafik - Don't Assume Anything -- Redshift Software, Inc. - http://redshift-software.com -- rrivera/acm.org - grafik/redshift-software.com -- 102708583/icq - grafikrobot/aim - grafikrobot/yahoo

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[Threads] Three Issues with Boost.Threads
by Daniel Winsor 07 Oct '06

07 Oct '06

Let's say I wanted to create my own thread pool class. I attempted this at first by making a thread manager class and in its constructor creating boost::thread objects and letting the objects expire naturally, when they went out of scope. The threads themselves and its function seemed to be running fine, but when I started encountering problems I wondered if the thread object needed to remain in scope. So I switched to creating boost::thread objects on the heap with new, but this didn't solve my problems, and by doing it this way I found out about the mem leaks. So my first question is what is the best way to make a thread pool, and are there any pratfalls to watch out for? I made what I thought was a simple input / output scheme for the thread functions. Please see the code attached. The thread functions sleep while waiting on the main thread to add data to an input queue. The thread then pops it, and locks a mutex while executing. When done, it puts the data on the output queue (order doesn't matter) and the mutex is unlocked. The main thread is checking for when the input queue is empty, and when it is, it tries to lock all the thread mutexes. Although the input queue may be empty, the thread may still be executing and the output would not be full, thus the thread mutex. The problem I was getting was that the thread manager seemed to be ignoring mutexes. You can see the problem in action with the attached code. What you are looking for is when the size of the output is not what you put in. You will need to run the code many times (~30) because the error is infrequent. A much more common error (1 in 3) I am getting is that I get an access violation in boost::mutex::scoped_lock. I don't know if they are related or what. I found if I have a memory intensive app in the background then there aren't as many access violations, so run one while looking for the other bug or you will go crazy. So basically I am new to threading and I don't know if these are bugs in my code, the boost::threads library, or what. Any suggestions on the abstraction of the thread pool or anything else is welcome. Boost 1.33.1 Windows XP x64 (win32 debug app) Intel Core 2 Duo

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