May 2010 - Boost-users - lists.preview.boost.org

[statechart] Passing parameters from event to State Local Storage
by Christophe Bourez 16 Nov '16

16 Nov '16

I need to maintain a parameter into the state local storage. This parameter is initially contained in the event that causes the transition to the target state. I give hereafter a small illustrative example. typename sc = boost::statechart; class EvTest : public sc::event<EvTest> { public: EvTest(std::size_t val) : value(val) {} std::size_t getValue() const { return this->value; } private: std::size_t value; }; class MyStateMachine; class StSource; class StTarget; class StSource : public sc::simple_state<StSource, MyStateMachine> { public: typedef sc::custom_reaction<EvTest> reactions; sc::result react(const EvTest &event) { // How to pass event.getValue() to the target state ? transit<StTarget>(); } }; class StTarget : public sc::simple_state<StTarget, MyStateMachine> { public: StTarget(std::size_t val) : val(value) {} private: std::size_t value; }; Thanks, Christophe

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Statechart serialization
by mbrodeur65 04 Mar '15

04 Mar '15

Hi, I'm looking for a solution to serialize boost::statechart objects. I'm aware that this feature is on the statechart library todo list but was wondering if there are any workaround to achieve this with the latest boost release (1.34) ? thanks for your help ! mbrodeur65 -- View this message in context: http://www.nabble.com/Statechart-serialization-tf4131326.html#a11749139 Sent from the Boost - Users mailing list archive at Nabble.com.

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[Statechart] How to decide between post_event and process_event atrun time ?
by Philippe DAVID 22 Jul '14

22 Jul '14

Hi, I have a method in which I want to post/process an event. The thing is, this method can be called from outside the state machine (so I need to call process_event), or indirectly by a reaction of the state machine (in this case I must call post_event since process_event is not reentrant). I don't want to write 2 distinct methods to do this (one that calls post, and the other process), I would much rather prefer adding a 'if' in my method that tells me if I have to call process_event or post_event (if I'm being called indirectly by the state machine or not). Is there a way to do this with statechart ? regards, Philippe

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[asio] resolver::cancel() problem
by Matthew Edwards 14 Mar '14

14 Mar '14

In my application (and a separate test program) it seems as though the cancel() function on the resolver does not work as intended. For async resolves, the cancel functionality should abort them immediately and pass an 'operation aborted' error code to the callback handler. In my tests, I will resolve an invalid domain (this causes the resolve to take a few seconds, to demonstrate the problem), sleep for 100ms, then call cancel on the resolver object. No cancelling actually occurs, and the callback is simply triggered after a few seconds with a "No host found" error code, not the expected operation aborted. Has anyone experienced this before, or know how I might be using the resolver incorrectly?

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[BGL] Having a cost function as weight map
by Maxime van Noppen 06 Sep '13

06 Sep '13

Hi, I can't find how to do this pretty basic thing : having a function instead of a field to compute the cost of edges for various path finding algorithms. I couldn't find the answer in the documentation and Google was of no help. Did I miss something obvious ? Example : ------------------- #include <boost/graph/dijkstra_shortest_paths.hpp> #include <boost/graph/graph_traits.hpp> #include <boost/graph/adjacency_list.hpp> struct my_edge { double cost() const { return cost_ * 2; } double cost_; }; struct my_node { }; int main() { typedef boost::adjacency_list< boost::vecS, boost::vecS, boost::directedS, my_node, my_edge > graph_t; typedef boost::graph_traits<graph_t>::vertex_descriptor vertex_t; graph_t graph; vertex_t v /*= ... */; using boost::weight_map; // Works : boost::dijkstra_shortest_paths(graph, v, weight_map(boost::get(&my_edge::cost_, graph))); // Doesn't compile : //boost::dijkstra_shortest_paths(graph, v, // weight_map(boost::get(&my_edge::cost, graph))); } ------------------- Thanks ! -- Maxime

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can't get first example in boost tutorial to work
by 7stud 11 Mar '13

11 Mar '13

I'm trying to install boost on mac osx 10.4.7. I followed the tutorial "Getting Started on Unix Variants" found here: http://www.boost.org/doc/libs/1_35_0/ more/getting_started/unix-variants.html Following the instructions in the tutorial, I installed boost in /usr/local as instructed, so my directory structure is: /usr/local/boost_1_34_1/boost But when I run the first example in the tutorial: #include <boost/lambda/lambda.hpp> #include <iostream> #include <iterator> #include <algorithm> int main() { using namespace boost::lambda; typedef std::istream_iterator<int> in; std::for_each(in(std::cin), in(), std::cout << (_1 * 3) << " " ); } I get the error(among others): error: boost/lambda/lambda.hpp: No such file or directory If I change the include path to: #include </user/local/boost_1_34_1/boost/lambda/lambda.hpp> I get the error(among others): error: boost/lambda/core.hpp: No such file or directory But core.hpp is in the lambda directory: /usr/local/boost_1_34_1/boost/lambda$ ls algorithm.hpp control_structures.hpp lambda.hpp bind.hpp core.hpp loops.hpp casts.hpp detail numeric.hpp closures.hpp exceptions.hpp switch.hpp construct.hpp if.hpp I'm using the Xcode 2.4 IDE to run my C++ programs. I also tried to execute the program from the command line with the original include path: #include <boost/lambda/lambda.hpp> but I get the same error: ~/2testing/dir1$ g++ prog1.cpp prog1.cpp:1:35: error: boost/lambda/lambda.hpp: No such file or directory prog1.cpp: In function 'int main()': prog1.cpp:8: error: 'boost' has not been declared prog1.cpp:8: error: expected namespace-name before ';' token prog1.cpp:8: error: '<type error>' is not a namespace prog1.cpp:11: error: '_1' was not declared in this scope I get the same errors again with the full include path: #include </user/local/boost_1_34_1/boost/lambda/lambda.hpp> $ g++ prog1.cpp In file included from prog1.cpp:1: /usr/local/boost_1_34_1/boost/lambda/lambda.hpp:14:33: error: boost/lambda/core.hpp: No such file or directory /usr/local/boost_1_34_1/boost/lambda/lambda.hpp:21:52: error: boost/lambda/detail/operator_actions.hpp: No such file or directory /usr/local/boost_1_34_1/boost/lambda/lambda.hpp:22:61: error: boost/lambda/detail/operator_lambda_func_base.hpp: No such file or directory /usr/local/boost_1_34_1/boost/lambda/lambda.hpp:23:63: error: boost/lambda/detail/operator_return_type_traits.hpp: No such file or directory /usr/local/boost_1_34_1/boost/lambda/lambda.hpp:26:45: error: boost/lambda/detail/operators.hpp: No such file or directory /usr/local/boost_1_34_1/boost/lambda/lambda.hpp:30:46: error: boost/lambda/detail/member_ptr.hpp: No such file or directory prog1.cpp: In function 'int main()': prog1.cpp:8: error: 'boost' has not been declared prog1.cpp:8: error: expected namespace-name before ';' token prog1.cpp:8: error: '<type error>' is not a namespace prog1.cpp:11: error: '_1' was not declared in this scope What path should I be using? Or, should I set an environment variable somewhere?

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[multi_array] operator= requires resize - why?
by Markus Werle 04 Jun '12

04 Jun '12

Hi! IMHO the behaviour of operator= for multi_array is a little bit broken. A lot of preconditions required: template <typename ConstMultiArray> multi_array_ref& operator=(const ConstMultiArray& other) { [...] // make sure the dimensions agree assert(other.num_dimensions() == this->num_dimensions()); assert(std::equal(other.shape(),other.shape()+this->num_dimensions(), this->shape())); Besides the fact that I get mad about asserts instead of exceptions (please change this to a way users may choose) why do we have such an odd behaviour here? >From page 1, line 3 of the docs I cite: "The interface design is in line with the precedent set by the C++ Standard Library containers" - this is not true for operator=, since std::<container>::operator= works fine for me all the time _without_ any resize. Could we please change the behaviour of multi_array::operator= to take care of resize where in need to? IMHO operator= should result in a true copy ignoring previous state. Markus

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MSVC Visualizers Update
by Filip Konvička 28 Jul '11

28 Jul '11

Hi all, I've just updated the Boost visualizers wiki page at https://svn.boost.org/trac/boost/wiki/DebuggerVisualizers I updated the visualizer for Boost.MultiIndex, which did not work since Boost 1.35. I also added new visualizers for Boost.DateTime (ptime and time_duration) and a simple boost::shared_ptr visualizer. The visualizers are available for checkout via SVN at https://svn.boost.org/svn/boost/sandbox/boost_docs/subprojects/DebuggerVisu… Cheers, Filip

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Asio unhandled exception
by Łukasz Majewski 20 May '11

20 May '11

Hello, I created a server single thread async (linux) and clinet (win). Every time client is close while server is writing to the socket connected to this client exception appears: terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::system::system_error>>' what(): Transport endpoint is not connected Aborted and server is terminated. I dont know why this exception is unhandled. int main( int argc, char** argv ) { try { boost::asio::io_service io_service; quotation_server server( io_service ); while ( true ) { try { io_service.run(); } catch( ... ){} } } catch ( std::exception& e ) { LOG << e.what() << std::endl; } catch( ... ) { LOG << "Unexpected exception" << std::endl; } return 0; }

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vs 2010 can't find correct boost lib version?
by Li, Tieniu 30 Mar '11

30 Mar '11

I built boost with visual studio 2010. Libraries of *-vc100-* are generated correctly. When trying to using boost.thread, VS 2010 generated error message: can't find *-vc90-*.lib. Any idea and fixing? Thanks a lot.

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Simple serial port demonstration with boost asio asynchronous I/O
by Jeff Gray 26 Jan '11

26 Jan '11

A couple of weeks ago I posted a simple asynchronous demonstration of a telnet client using boost asio TCP network code. I have changed this code to turn it into a simple serial terminal application using the serial port support in the new version of boost asio. It required no changes at all the the read or write code. I just altered the initialization to use a serial port instead of a socket. Note that this is not intended to show how a fully functional application would work. There are plenty of areas that are not handled in this code. But it shows the idea and it's easy to build on this once you've got it working. Hope this helps someone else get started... Jeff

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[units] subtract_typeof_helper<> help!
by Terry Golubiewski 04 Jan '11

04 Jan '11

I'm trying to use boost::geometry and boost::units together. For some reason boost::geometry doesn't represent the difference of two points as vectors. So, I'm making my own Vector class and defining Vector = Point - Point. The sample program below doesn't compile because I need to tell the units library about the special properties of point subtraction (I think). terry #include <boost/geometry/geometry.hpp> #include <boost/units/systems/si.hpp> #include <boost/units/quantity.hpp> #include <boost/units/io.hpp> #include <iostream> #include <iomanip> using namespace std; using namespace boost; using namespace boost::geometry; using namespace boost::units; typedef point<double, 3, cs::cartesian> Point; class Vector { Point _impl; friend Vector operator-(const Point& lhs, const Point& rhs); explicit Vector(Point p) : _impl(p) { } public: Vector() : _impl(0) { } Vector(double dx, double dy, double dz=0) : _impl(dx, dy, dz) { } friend ostream& operator<<(ostream& os, const Vector& v) { return os << dsv(v._impl); } }; // Vector inline Vector operator-(const Point& lhs, const Point& rhs) { Point tmp(lhs); subtract_point(tmp, rhs); return Vector(tmp); } inline ostream& operator<<(ostream& os, const Point& pt) { return os << dsv(pt); } int main() { Point p1(1, 2, 3); Point p2(4, 5, 6); typedef quantity<si::length, Point> Position; typedef quantity<si::length, Vector> Displacement; Position start( p1 * si::meters); Position finish(p2 * si::meters); Displacement disp(finish - start); cout << "disp=" << disp << endl; return EXIT_SUCCESS; } // main

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[Program Options] Positional args in help message
by Lindley M French 10 Nov '10

10 Nov '10

The examples for how to use positional arguments are great and seem to work fine. However, I'm wondering if there's an automatic way to include that information in the help message. In particular, since the tutorial goes to the trouble of telling you how to exclude the positional options from the options help, it would be nice to know what to replace it with. I could manually write a line detailing the usage before outputting the options description, of course, but I was wondering if there was anything in PO to handle this automatically.

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[Asio]What's the behavior of socket.async_write() after socket.close() is called?
by 鑫炜廖 05 Nov '10

05 Nov '10

Hi, If I call socket.close() but I still have some data in my buffer, can I call async_write() later? When I call socket.close(), maybe an async_write operation is running, when it's complete I want to send data in another buffer(data written while previous async_write() is running, before socket.close() was called), but the socket is closed.Does it work in this situation?If not, what's the alternative way? The code looks like this: char front_buffer[kBufferSize]; char back_buffer[kBufferSize]; void HandleWrite(...) { //socket is closed. Does this work? socket.async_write(back_buffer, ...); } socket.async_write(front_buffer, HandleWrite); // write data to back_buffer socket.close();

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Polymorphic serialization with polymorphic archives problems... [part 2]
by Bogdan 03 Nov '10

03 Nov '10

First I would like to confirm I tested Robert Ramey's fix (@60273) for multiple registrations and it looks good in my runs. Thank you Robert! On the other hand, I am under the impression there is a bug in void_caster::recursive_unregister(), although I am not 100% certain about the reason: that function member is called in the destructors of the void caster template classes and makes use of the void_caster_registry singleton (more specifically the type_set). I believe it searches the set for all the void caster entries that are descendants of the current one (i.e., the one being destroyed) and performs the following ops: - delete the shortcuts. - remove the corresponding entries from the set. However, void_caster::recursive_unregister() DOESN'T REMOVE FROM THE REGISTRAR the entry corresponding to the current void_caster(). This creates the problem below: consider a scenario where a dll containing some serialization functionality is loaded explicitly at runtime (i.e., using LoadLibrary() on Windows or dlopen on Unix). There are no parent-child relationships among the serialized classes registered by that DLL: all serialized classes are derived from one abstract base. While unloading the library, its void_caster singletons are destroyed but there are no shortcuts to remove from the global registrar since there are no parent-child relationships. All entries corresponding to those are still in the global registrar and POINT TO THE void_caster SINGLETONS ALREADY DESTROYED AND DISCARDED. When the main process exits, the registrar traversal repeats for whatever process-bound void_caster singletons are about to be destroyed. During these subsequent traversals, void_caster::recursive_unregister() visits the entries left after the previous explicit dll download and tries to identify the parent-child relationship. In doing so, it accesses the dangling vc pointers generating access violations: void_cast.cpp(Line 286): const void_caster * vc = *it; void_cast.cpp(Line 287): if(vc->m_parent == this){ //<--------------------- here is the access violation I can reproduce the crash systematically, but I am not sure about the reason or whether a simple unregistration is enough. I believe this is (again) a question for Robert, but I thank for any feedback I might get. Bogdan

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upgrade_to_unique_lock doesn't compile with vc2010
by Braden McDaniel 16 Sep '10

16 Sep '10

Using Boost 1.43, this program: # include <boost/thread.hpp> int main() { boost::shared_mutex mutex; boost::upgrade_lock<boost::shared_mutex> lock(mutex); boost::upgrade_to_unique_lock<boost::shared_mutex> write_lock(lock); } ... produces this error when compiled with Visual C++ 2010: C:\Users\braden>cl /I include/boost-1_43 /MD /EHsc upgrade_to_unique_lock_test.cpp Microsoft (R) C/C++ Optimizing Compiler Version 16.00.30319.01 for x64 Copyright (C) Microsoft Corporation. All rights reserved. upgrade_to_unique_lock_test.cpp include/boost-1_43\boost/thread/locks.hpp(823) : error C2679: binary '=' : no operator found which takes a right-hand operand of type 'boost::unique_lock<Mutex>' (or there is no acceptable conversion) with [ Mutex=boost::shared_mutex ] include/boost-1_43\boost/thread/locks.hpp(659): could be 'boost::upgrade_lock<Mutex> &boost::upgrade_lock<Mutex>::operator =(boost::upgrade_lock<Mutex>&)' with [ Mutex=boost::shared_mutex ] include/boost-1_43\boost/thread/locks.hpp(710): or 'boost::upgrade_lock<Mutex> &boost::upgrade_lock<Mutex>::operator =(boost::detail::thread_move_t<T>)' with [ Mutex=boost::shared_mutex, T=boost::upgrade_lock<boost::shared_mutex> ] include/boost-1_43\boost/thread/locks.hpp(717): or 'boost::upgrade_lock<Mutex> &boost::upgrade_lock<Mutex>::operator =(boost::detail::thread_move_t<T>)' with [ Mutex=boost::shared_mutex, T=boost::unique_lock<boost::shared_mutex> ] while trying to match the argument list '(boost::upgrade_lock<Mutex>, boost::unique_lock<Mutex>)' with [ Mutex=boost::shared_mutex ] include/boost-1_43\boost/thread/locks.hpp(820) : while compiling class template member function 'boost::upgrade_to_unique_lock<Mutex>::~upgrade_to_unique_lock(void)' with [ Mutex=boost::shared_mutex ] upgrade_to_unique_lock_test.cpp(7) : see reference to class template instantiation 'boost::upgrade_to_unique_lock<Mutex>' being compiled with [ Mutex=boost::shared_mutex ] I've searched a bit for previous reports of this sort of thing and I haven't found any. Hopefully that means I'm just doing something wrong. -- Braden McDaniel <braden(a)endoframe.com>

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Help with shared_ptr and template
by Mario Chacon 10 Sep '10

10 Sep '10

Hello: I have this problem and I do not how to fix it, I know I cannot write template typedefs, its a limitiation of the C++ syntax, right? or I'm wrong? I saw that the best way is to wrap your typedefs in a struct, which can be templated, but I'm still stack with problems. The best way to explain it's with an example: #include <cstdlib> #include <iostream> #include <boost/shared_ptr.hpp> template< typename tvalue > class CValue { public: CValue( tvalue value ) : value_(value) {}; private: tvalue value_; }; template< typename tvalue > struct Type{ typedef boost::shared_ptr< CValue< tvalue > > pValue; }; int main(int argc, char *argv[]) { Type<bool>::pValue a; return EXIT_SUCCESS; } How can I create a shared_ptr for the template class "CVALUE"?? Please I do not know what else I can prove... :( Thank you.. Mario.. Salu2...

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[1.43.0] Release notice
by Beman Dawes 19 Aug '10

19 Aug '10

Release 1.43.0 of the Boost C++ Libraries is now available. These open-source libraries work well with the C++ Standard Library, and are usable across a broad spectrum of applications. The Boost license encourages both commercial and non-commercial use. This release contains two new libraries (functional/factory, functional/forward), a major range library upgrade, plus numerous enhancements and bug fixes for other libraries. For details, including download links, see http://www.boost.org/users/news/version_1_43_0 The release can also be downloaded directly from SourceForge. See http://sourceforge.net/projects/boost/files/ To install this release on your system, see http://www.boost.org/doc/libs/1_43_0/more/getting_started/index.html Thanks to all who contributed, --The Boost release team

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[array] range check (at compile time)
by alfC 23 Jun '10

23 Jun '10

Hi, Lately I find myself using boost::array intesively, specially in small demo programs. Sometimes, when "manually" accessing the elements I type a index out of range. The library can detect these errors once the program is running but I found this a waste, also I was surprised not to see this kind of static check not implemented in the library. So I wanted to see if I could enforce range checking at compile time, and I come out with this solution. namespace boost{ //sorry about the namespace name template<size_t IDX, typename T, size_t N> const T& get(boost::array<T, N> const& arr){ BOOST_STATIC_ASSERT(IDX<N); return arr[IDX]; } template<size_t IDX, typename T, size_t N> T& get(boost::array<T, N>& arr){ BOOST_STATIC_ASSERT(IDX<N); return arr[IDX]; } } #include<iostream> void main(){ boost::array<double, 3> a = {1,2,3}; std::clog<<boost::get<2>(a)<<std::endl; // ok, (namespace specification needed, why?) std::clog<<boost::get<5>(a)<<std::endl; //does not compile return 0; } (I though about using enable_if instead of BOOST_STATIC_ASSERT but that would be too much overengineering.) Is this implemented already in some other way? Alfredo

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BOOST_FOREACH infinite loop issue
by yabcok 11 Jun '10

11 Jun '10

Hi, I have a problem with BOOST_FOREACH never ending under specific conditions described here: http://stackoverflow.com/questions/2881491/need-help-with-boost-foreach-com… Could anyone help me understand what's going on? Best regards, Jacek Ławrynowicz

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[GIL] Some questions about 2D iteration
by Brett Gmoser 08 Jun '10

08 Jun '10

Hello everybody, I've been toying with GIL a bit for the last few days in my spare time, and I've got a few questions that I can't seem to find answers to in the documentation. The following function which I've written works, but I'd like to get a better understanding of how to use iterators to accomplish the same task (the documentation says that view(x, y) = z is inefficient), as well as a few other things. The job of this function is to crop an image, discarding any white background. In other words, find the top-most, left-most, right-most, and bottom-most pixel that isn't the background color (white), and crop the image around those coordinates. template <typename ViewType, typename ImageType> void crop_image(ViewType& src, boost::scoped_ptr<ImageType>& dst) const { int top = 0; int right = 0; int bottom = 0; int left = 0; // Find the top, right, bottom, and left extents. First, find the top. for(int y=0; y < src.height(); ++y) { for(typename ViewType::x_iterator xpos = src.row_begin(y); xpos != src.row_end(y); ++xpos) { if(rgb8_pixel_t(255,255,255) != *xpos) { top = y; break; } } if(top) break; } // ... Do similar things for finding the right, bottom, and left extents. // We should now have the rectangle of the image, and it should be easy to copy everything over. dst.reset(new ImageType(1 + (right - left), 1 + (bottom - top))); for(int x = left; x <= right; ++x) for(int y = top; y <= bottom; ++y) view(*dst)((x - left), (y - top)) = src(x, y); } So, my first question is - is there a better way to do that first chore of finding each extent? Such as a way to use std::find or std::find_if, keeping in mind that I have to do two of the four sides in reverse (bottom-to-top to find bottom-most, right-to-left to find right-most)? The next question is about the final loop which copies from the source view to the newly created destination image. It seems that using iterators, I could do something like this, assuming that I had the above loops find iterator positions for all four extents (left, top, bottom, and right are iterators): // Start the copying process by creating a column iterator for the destination table beginning at column 0. // The top iterator starts at the top-most extent - and we cycle through the source image in a top-to-bottom, // left-to-right fashion. for(typename ImageType::view_t::y_iterator dst_y = view(*dst).col_begin(0); top <= bottom; ++dst_y,++top) { // The left iterator needs to be initialized with whatever row we're on - this appears to be impossible. There doesn't // seem to be any suitable way to do this, so consider it pseudocode. typename ViewType::x_iterator src_x = left.y(); // The destination X iterator also needs to know what Y position to begin on. You'd think you would be able to initialize // it with an iterator position, but it doesn't seem that you can. Again, this doesn't actually compile (it's the // view(*dst).row_begin(y) part). for(typename ImageType::view_t::x_iterator dst_x = view(*dst).row_begin(y); // Here, I need to be able to tell if src_x has hit the right extent. src_x <= right doesn't seem it will work, because // again right doesn't know it's Y position. src_x != right; // And increment both src and destination iterators. ++src_x,++dst_x ) { // Finally do the should-be-simple task of assigning the source pixel to the destination pixel. *dst_x = *src_x; } } If you read the comments, most of this doesn't seem to be possible. I've seen that there is a "transform_pixel_positions" algorithm that may do something close to what I want, but unfortunately I cannot find any documentation on it (other than mentioning that it exists, and a short example that really doesn't help - one of the few examples actually provided by the documentation). It seems to pass a unary argument to a functor, but that doesn't seem useful if I don't have both the X and Y coordinates, or an X iterator and Y iterator. Also, nowhere can I find where it says what the argument passed to the functor actually /is/. So after I figure these few things out, I'm hoping to be able to speed up my program a little bit. Right now everything is pretty slow using that view(x, y) method. I'd appreciate any help that anybody can give, thanks! Brett

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[phoenix][lambda] lambda to phoenix translation: get sig (signature) from actor
by alfC 05 Jun '10

05 Jun '10

hi, what is the translation of boost.lambda typename LambdaExp::template sig<tuple<InputType> >::type in Boost.Phoenix? my best try was: actor<LambdaExp>::result< vector<InputType> >::type but it doesn't compile. Thank you, Alfredo

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[Test] Tests execution order and depends_on method.
by Maria Kozinska 05 Jun '10

05 Jun '10

Hello, I have couple of question to Boost.Test framework. I'd like to ask why test_unit::depends_on(test_unit*) method is not described in User's guide. Is it only for internal use by framework or I can use it freely? I assume, that it can be used to determine precedence of one test before another. What happens if there is a cycle in dependence graph? If a test case fails, are dependant on it tests executed? In what order are executed automatically registered test suites and test cases? And in what order when they are manually registered (without any depends_on)? How this order is affected by depends_on method? Thanks for answer. Greetings, Maria

2 1

[lamda] smart self binding of a function object
by alfC 02 Jun '10

02 Jun '10

Hi, I usually have function-classes that take two arguments. class f{ double operator()(double x, double y) const { x*y+y; } }; called as: f myf; cout << myf(4.,3.); for some purposes I need a function of only one variable (parametrized in the first or second argument. So I end up doing: using boost::function; using namespace boost::lambda; function<double(double)> myf_at5 = bind(&f::operator(), myf, 5., _1); // myf_at5 is myf(5.,*) So, now I can pass myf_at5 to something that accepts a function of one variable. root_finder( myf_at5, ...); since I have access to f I would like to make f smart enough to handle its own binding. Eg. class f{ ... // same as before function<double(double)> operator()(double x_value, YYYY y_arg){ return bind( &f::operator(), //maybe needs cast to double(*) (double,double) *this, x_value, y_arg ); } function<double(double)> operator()(XXXX x_arg, double y_value){ return bind( &f::operator(), //maybe needs cast *this, x_arg, y_value ); } }; The question is: What should be the type of XXXX and YYYY? in such a way that I can just call root_finder( myf(5., _1) , ... ); or more complicated things like root_finder( myf(5., _1 * 2.), ...); in other words, myf(5.,_1) is the same as the old bind(&f::operator(), myf, 5., _1); Thank you, Alfredo answers using other libraries are also accepted :)

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Boost 1.43 - Exception before main() is called
by Rob Yull 01 Jun '10

01 Jun '10

I recently upgrade from boost 1.42 to 1.43. All of a sudden, the project I was working on seems to be throwing an exception before main() is called. I was able to reproduce this error in the example below. Using 1.42, it executes just fine. Using 1.43, an exception is thrown before main is reached. In some of my classes, I have a static mutex variable that I lock before I manipulate other static variables in the class (as seen below). main.cpp - Start #include "Test.hpp" int main() { Test test; return 0; } main.cpp - End Test.hpp - Start #ifndef DEFINE_TEST_HPP #define DEFINE_TEST_HPP #include <boost/thread.hpp> class Test { public: Test(); ~Test(); private: typedef boost::mutex StaticMutex; static StaticMutex s_Mutex; typedef boost::lock_guard<StaticMutex> StaticMutexLock; }; #endif // DEFINE_TEST_HPP Test.hpp - End Test.cpp - Start #include "Test.hpp" Test::StaticMutex Test::s_Mutex; Test::Test() { const StaticMutexLock Lock(s_Mutex); } Test::~Test() { } Test.cpp - End The code above, when using boost 1.43, produces the following error in both VC2010 Express and VC2005 Pro. First-chance exception at 0x7569b727 (KernelBase.dll) in BoostTest.exe: Microsoft C++ exception: boost::exception_detail::clone_impl<boost::exception_detail::bad_alloc_> at memory location 0x0030f6e4.. The call stack (>>> is where the exception is caught). KernelBase.dll!_RaiseException@16() + 0x58 bytes msvcr100d.dll!_CxxThrowException(void * pExceptionObject, const _s__ThrowInfo * pThrowInfo) Line 157 C++ >>>BoostTest.exe!boost::copy_exception<boost::exception_detail::bad_alloc_>( const boost::exception_detail::bad_alloc_ & e) Line 47 C++ BoostTest.exe!boost::exception_detail::get_bad_alloc<42>() Line 80 + 0x9f bytes C++ BoostTest.exe!`dynamic initializer for 'boost::exception_detail::exception_ptr_bad_alloc<42>::e''() Line 94 + 0x28 bytes C++ msvcr100d.dll!_initterm(void (void)* * pfbegin, void (void)* * pfend) Line 873 C BoostTest.exe!__tmainCRTStartup() Line 473 + 0xf bytes C BoostTest.exe!mainCRTStartup() Line 371 C kernel32.dll!@BaseThreadInitThunk@12() + 0x12 bytes ntdll.dll!___RtlUserThreadStart@8() + 0x27 bytes ntdll.dll!__RtlUserThreadStart@8() + 0x1b bytes Did something change between 1.42 and 1.43 that would cause this? -Rob Yull

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