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[BGL] there is no in_edges() function for adjacency_matrix<>
by Dmitry Bufistov 06 Feb '06

06 Feb '06

Hi, A huge disappointment again came to me today. I used boost::adjacency<boost::directedS> class for representation of simple Petri net. I was trying to define the following function ////////////////////////////////////////// bool if_enabled(transition_descriptor_t tr, graph_t net) { assert((net[tr].m_node_type == TRANSITION) && "if_enabled called with non transition node"); BGL_FORALL_INEDGES_T(tr, ed, net, graph_t) { if (net[boost::source(ed, net)].m_tokens_number < net[ed].m_weight) return false; } return true; } ////////////////////////////////////////////////////////// But I failed because of lack of boost::in_edges() function specialization for type that I've chosen. Am I doing something wrong? Any ideas how to implement my function in resonable way would be greatly appreciated. Note: all works fine with "adjacency_list<vecS, vecS, bidirecrionalS>" Many thanks in advance, --dima

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Boost thread library wrapper
by boostguy＠kapiladhanvi.com 06 Feb '06

06 Feb '06

Hi all, I am trying to write a generalized object oriented wrapper for thread library implementation of Boost. Boost threads take a function name as an argument when creting a thread. I would like create a warpper in C++ which would in some respects mimic JAVA and have a runnable interface which an threaded application would implement. This code would explain what I want to do.. but my question is how can I do it or if there are already some wrappers out there that I can use for boost threads? Sample code : ----- MyThread.h ----- #include "myRunnable.h" #include <boost/thread/thread.hpp> class MyThread { private: Runnable& task; boost::thread thr; public: MyThread( Runnable& threadTask ) : task( threadTask ), thr( &task.run) // how do I do this ? { } }; --------------------------- Thanks, Dhanvi

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stopping a boost::thread
by xargon 06 Feb '06

06 Feb '06

Hi everyone, I am trying to use the boost multithreading library. I am having a problem as the join() function for the thread never returns. I am using a boolean variable to indicate when the thread should stop running. Here is basically a stub of what I am doing: //........................................ bool m_RunThread = false; scoped_ptr myThread; //....................................... void MyObject::StartThread() { m_RunThread = true; myThread.reset(new boost::thread(boost::bind (&MyObject::MyThreadFunc, this))); } void MyObject::StopThread() { m_RunThread = false; myThread.join(); // this function never returns! ... Never gets here.... } void MyObject::MyThreadFunc() { while (m_RunThread) { // do something } } However, the join() function in StopThread never returns. I think that using a variable to synchronize this is probably not a good idea. Any thoughts and suggestions? Cheers, K

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[Review] Shmem Library
by Fred Bertsch 06 Feb '06

06 Feb '06

Hello everyone, The review of the proposed Boost Shmem library written by Ion Gaztañaga starts today (February 6th, 2006) and ends after 10 days (February 16, 2006). Documentation for the library can be found online here: http://tinyurl.com/e2os3 Both documentation and the library itself can be downloaded here: http://tinyurl.com/9t5qy --------------------------------------------------- About the library: The Shmem Library simplifies the use of shared memory and provides some STL compatible allocators that allow shared memory STL container placement. It also offers helper classes, such as offset pointers, process shared mutexes, condition variables, and named semaphores. Library users can apply all STL algorithms and utilities with created shared memory objects. Shmem also wants to present a portable implementation, unifying UNIX and Windows shared memory object creation, providing simple wrapper classes. Shmem offers the following to the user: - Portable synchronization primitives for shared memory, including shared mutexes and shared condition variables. - Dynamic allocation of portions of a shared memory segment. - Named allocation in shared memory. Shmem can create objects in shared memory and associate it with a c-string offering a similar mechanism to a named new/delete. Created object can be found by other processes using Shmem framework. - Offset pointers that can be safely placed in shared memory to point to another object of the same shared memory segment even if the memory is mapped to a different address. - STL compatible shared memory allocators so that STL containers can be placed in shared memory. Shmem also offers a pooled node allocator to save and optimize shared memory allocation in node containers. - STL compatible containers for systems with STL implementations that cannot deal with shared memory. The user can map shared memory to different addresses and use STL compatible containers and algorithms. Useful to store common data or implement shared memory databases. These containers also show how STL compatible containers can make use of shared memory STL compatible allocators to place such containers in the shared memory. Shmem also offers the basic_string pseudo-container to use full-powered C++ strings in shared memory. --------------------------------------------------- Please always state in your review, whether you think the library should be accepted as a Boost library! Additionally please consider giving feedback on the following general topics: - 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? Fred Bertsch Review Manager

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[BGL] Converting my graph to BGL.
by Robert Bigaignon 06 Feb '06

06 Feb '06

Hi all, I have been trying to convert an existing graph implementation to BGL. I have followed this example http://www.boost.org/libs/graph/doc/leda_conversion.html and implemented the incidence_graph, adjacency_graph and vertex_list_graph concepts. The following concept check compiles : boost::function_requires< boost::GraphConcept<graph_t> >(); boost::function_requires< boost::IncidenceGraphConcept<graph_t> >(); boost::function_requires< boost::AdjacencyGraphConcept<graph_t> >(); boost::function_requires< boost::VertexListGraphConcept<graph_t> >(); and the basic functions for these concepts seems to work properly (out_degree(), num_vertices(), etc..). But when I try to call an algorithm, like for instance articulation_points() (which takes a graph which model must be of Vertex List Graph and Incidence Graph), compilation fails: /usr/include/boost/graph/biconnected_components.hpp: In function 'OutputIterator boost::articulation_points(const Graph&, OutputIterator) [with Graph = vcsn::Graph<vcsn::labels_are_series, std::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, vcsn::algebra::polynom<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool>, char, vcsn::NoTag, vcsn::geometry>, OutputIterator = std::back_insert_iterator<std::vector<vcsn::handler<vcsn::state_h>, std::allocator<vcsn::handler<vcsn::state_h> > > >]': test2.cc:77: instantiated from here /usr/include/boost/graph/biconnected_components.hpp:246: error: no matching function for call to 'get(boost::vertex_index_t, const vcsn::Graph<vcsn::labels_are_series, std::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, vcsn::algebra::polynom<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool>, char, vcsn::NoTag, vcsn::geometry>&)' Compilation exited abnormally with code 1 at Fri Feb 3 17:38:31 What did I forgot to do ? -- Robert

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Boost.Statechart: Cannot compile example with GCC 4.0.2?
by Bardur Arantsson 06 Feb '06

06 Feb '06

Hi all, I'm trying to compile the StopWatch.cpp example on SuSE10 and I'm getting a whole bunch of errors (or at least what gcc thinks are errors): $ gcc --version gcc (GCC) 4.0.2 20050901 (prerelease) (SUSE Linux) Copyright (C) 2005 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. $ g++ StopWatch.cpp /usr/include/c++/4.0.2/bits/stl_tree.h: In member function âvoid std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::destroy_node(std::_Rb_tree_node<_Val>*) [with _Key = const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*, _Val = std::pair<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>* const, std::list<boost::intrusive_ptr<const boost::statechart::event_base>, std::allocator<boost::intrusive_ptr<const boost::statechart::event_base> > > >, _KeyOfValue = std::_Select1st<std::pair<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>* const, std::list<boost::intrusive_ptr<const boost::statechart::event_base>, std::allocator<boost::intrusive_ptr<const boost::statechart::event_base> > > > >, _Compare = std::less<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*>, _Alloc = std::allocator<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*>]â: /usr/include/c++/4.0.2/bits/stl_tree.h:1096: instantiated from âvoid std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_erase(std::_Rb_tree_node<_Val>*) [with _Key = const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*, _Val = std::pair<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>* const, std::list<boost::intrusive_ptr<const boost::statechart::event_base>, std::allocator<boost::intrusive_ptr<const boost::statechart::event_base> > > >, _KeyOfValue = std::_Select1st<std::pair<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>* const, std::list<boost::intrusive_ptr<const boost::statechart::event_base>, std::allocator<boost::intrusive_ptr<const boost::statechart::event_base> > > > >, _Compare = std::less<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*>, _Alloc = std::allocator<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*>]â /usr/include/c++/4.0.2/bits/stl_tree.h:570: instantiated from âstd::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::~_Rb_tree() [with _Key = const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*, _Val = std::pair<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>* const, std::list<boost::intrusive_ptr<const boost::statechart::event_base>, std::allocator<boost::intrusive_ptr<const boost::statechart::event_base> > > >, _KeyOfValue = std::_Select1st<std::pair<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>* const, std::list<boost::intrusive_ptr<const boost::statechart::event_base>, std::allocator<boost::intrusive_ptr<const boost::statechart::event_base> > > > >, _Compare = std::less<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*>, _Alloc = std::allocator<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*>]â /usr/include/c++/4.0.2/bits/stl_map.h:92: instantiated from âboost::statechart::state_machine<MostDerived, InitialState, Allocator, ExceptionTranslator>::state_machine() [with MostDerived = StopWatch, InitialState = Active, Allocator = std::allocator<void>, ExceptionTranslator = boost::statechart::null_exception_translator]â StopWatch.cpp:74: instantiated from here /usr/include/c++/4.0.2/bits/stl_tree.h:389: error: no matching function for call to âstd::allocator<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*>::destroy(std::pair<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>* const, std::list<boost::intrusive_ptr<const boost::statechart::event_base>, std::allocator<boost::intrusive_ptr<const boost::statechart::event_base> > > >*)â /usr/include/c++/4.0.2/ext/new_allocator.h:109: note: candidates are: void __gnu_cxx::new_allocator<_Tp>::destroy(_Tp*) [with _Tp = const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*] /usr/include/c++/4.0.2/bits/stl_tree.h: In member function âstd::_Rb_tree_node<_Val>* std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_create_node(const _Val&) [with _Key = const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*, _Val = std::pair<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>* const, std::list<boost::intrusive_ptr<const boost::statechart::event_base>, std::allocator<boost::intrusive_ptr<const boost::statechart::event_base> > > >, _KeyOfValue = std::_Select1st<std::pair<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>* const, std::list<boost::intrusive_ptr<const boost::statechart::event_base>, std::allocator<boost::intrusive_ptr<const boost::statechart::event_base> > > > >, _Compare = std::less<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*>, _Alloc = std::allocator<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*>]â: /usr/include/c++/4.0.2/bits/stl_tree.h:793: instantiated from âtypename std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_insert(std::_Rb_tree_node_base*, std::_Rb_tree_node_base*, const _Val&) [with _Key = const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*, _Val = std::pair<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>* const, std::list<boost::intrusive_ptr<const boost::statechart::event_base>, std::allocator<boost::intrusive_ptr<const boost::statechart::event_base> > > >, _KeyOfValue = std::_Select1st<std::pair<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>* const, std::list<boost::intrusive_ptr<const boost::statechart::event_base>, std::allocator<boost::intrusive_ptr<const boost::statechart::event_base> > > > >, _Compare = std::less<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*>, _Alloc = std::allocator<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*>]â /usr/include/c++/4.0.2/bits/stl_tree.h:902: instantiated from âtypename std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::insert_unique(std::_Rb_tree_iterator<_Val>, const _Val&) [with _Key = const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*, _Val = std::pair<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>* const, std::list<boost::intrusive_ptr<const boost::statechart::event_base>, std::allocator<boost::intrusive_ptr<const boost::statechart::event_base> > > >, _KeyOfValue = std::_Select1st<std::pair<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>* const, std::list<boost::intrusive_ptr<const boost::statechart::event_base>, std::allocator<boost::intrusive_ptr<const boost::statechart::event_base> > > > >, _Compare = std::less<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*>, _Alloc = std::allocator<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*>]â /usr/include/c++/4.0.2/bits/stl_map.h:384: instantiated from âtypename std::_Rb_tree<_Key, std::pair<const _Key, _Tp>, std::_Select1st<std::pair<const _Key, _Tp> >, _Compare, _Alloc>::iterator std::map<_Key, _Tp, _Compare, _Alloc>::insert(typename std::_Rb_tree<_Key, std::pair<const _Key, _Tp>, std::_Select1st<std::pair<const _Key, _Tp> >, _Compare, _Alloc>::iterator, const std::pair<const _Key, _Tp>&) [with _Key = const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*, _Tp = std::list<boost::intrusive_ptr<const boost::statechart::event_base>, std::allocator<boost::intrusive_ptr<const boost::statechart::event_base> > >, _Compare = std::less<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*>, _Alloc = std::allocator<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*>]â /usr/include/c++/4.0.2/bits/stl_map.h:339: instantiated from â_Tp& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](const _Key&) [with _Key = const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*, _Tp = std::list<boost::intrusive_ptr<const boost::statechart::event_base>, std::allocator<boost::intrusive_ptr<const boost::statechart::event_base> > >, _Compare = std::less<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*>, _Alloc = std::allocator<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*>]â ../../../../boost/statechart/state_machine.hpp:576: instantiated from âvoid boost::statechart::state_machine<MostDerived, InitialState, Allocator, ExceptionTranslator>::defer_event(const boost::statechart::event_base&, const boost::statechart::detail::state_base<Allocator, boost::statechart::detail::rtti_policy>*) [with MostDerived = StopWatch, InitialState = Active, Allocator = std::allocator<void>, ExceptionTranslator = boost::statechart::null_exception_translator]â ../../../../boost/statechart/simple_state.hpp:495: instantiated from âboost::statechart::detail::reaction_result boost::statechart::simple_state<MostDerived, Context, InnerInitial, historyMode>::react_impl(const typename Context::inner_context_type::event_base_type&, typename Context::inner_context_type::rtti_policy_type::id_type) [with MostDerived = Stopped, Context = Active, InnerInitial = boost::mpl::list<mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, boost::statechart::history_mode historyMode = has_no_history]â StopWatch.cpp:188: instantiated from here /usr/include/c++/4.0.2/bits/stl_tree.h:367: error: no matching function for call to âstd::allocator<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*>::construct(std::pair<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>* const, std::list<boost::intrusive_ptr<const boost::statechart::event_base>, std::allocator<boost::intrusive_ptr<const boost::statechart::event_base> > > >*, const std::pair<const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>* const, std::list<boost::intrusive_ptr<const boost::statechart::event_base>, std::allocator<boost::intrusive_ptr<const boost::statechart::event_base> > > >&)â /usr/include/c++/4.0.2/ext/new_allocator.h:105: note: candidates are: void __gnu_cxx::new_allocator<_Tp>::construct(_Tp*, const _Tp&) [with _Tp = const boost::statechart::detail::state_base<std::allocator<void>, boost::statechart::detail::rtti_policy>*] ---- end of output ---- Does anyone have any clues to impart as to what's going on? -- Bardur Arantsson <bardur.arantsson(a)gmail.com> Bardur Arantsson <bardur(a)scientician.net> Bardur Arantsson <bardur(a)imada.sdu.dk>

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Re: [Boost-users] Getting started with Boost: what did you need to know?
by Hickman, Greg 06 Feb '06

06 Feb '06

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org > [mailto:boost-users-bounces@lists.boost.org] On Behalf Of > Foster Brereton > Sent: Friday, February 03, 2006 5:20 PM > I have found the mailing list archives proved helpful, but > took an inordinate amount of time to search through. Is it > possible to take threads in the mailing lists that look > something like this: > - A: I have problem XYZ > - B-Z: Oh, you need to do this > - A: That fixed it, thanks! > and convert them to a FAQ or additional documentation? How about encouraging Boost library developers to maintain library-specific FAQs along with their respective library documentation? -Greg Hickman

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Re: [Boost-users] [BGL] there is no in_edges() function for adjacency_matrix<>
by Dmitry Bufistov 06 Feb '06

06 Feb '06

> > >Dmitry Bufistov <dmitry(a)lsi.upc.edu> writes: > > > >>Hi, >>A huge disappointment again came to me today. I used >>boost::adjacency<boost::directedS> class for representation of simple >>Petri net. I was trying to define the following function >>////////////////////////////////////////// >>bool if_enabled(transition_descriptor_t tr, graph_t net) { >> assert((net[tr].m_node_type == TRANSITION) && >>"if_enabled called with non transition node"); >> >> BGL_FORALL_INEDGES_T(tr, ed, net, graph_t) >> { >> if (net[boost::source(ed, net)].m_tokens_number < >>net[ed].m_weight) return false; >> } >> return true; >> } >> >>////////////////////////////////////////////////////////// >>But I failed because of lack of boost::in_edges() function >>specialization for type that I've chosen. >>Am I doing something wrong? >>Any ideas how to implement my function in resonable way would be greatly >>appreciated. >>Note: all works fine with "adjacency_list<vecS, vecS, bidirecrionalS>" >> >> > >By /definition/, BidirectionalGraph is a graph where you can enumerate >the incoming edges for any node. Unless you specify bidirectionalS, >an adjacency list won't be a BidirectionalGraph, and you can't use >in_edges. So everything is working just as I would expect it to. > > > But what about boost::adjacency_matrix<boost::directedS> ? Is there any way to iterate over all incoming edges? Where I can read your answer before I recieve e-mail? Time is very important ) Thank you, --dima

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<smart_ptr> scoped_ptr with an ownership flag?
by Guy Peleg 06 Feb '06

06 Feb '06

Suppose that class A that accepts a pointer to class B. An instance of A class can own the pointer or it can share it with some other A instances. The knowledge of whether or not the A instance should own the pointer is something that depends by the one that construct the instance. Shared_ptr seems as a good candidate for this problem but what if the pointer passed to the A instance might come from a legacy code that works with raw-pointers ? I think that a kind of scoped_ptr with a ownership flag will help here __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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[boost-users] [parameter] Error using positional arguments
by Cromwell Enage 06 Feb '06

06 Feb '06

In one of my projects the header files contain code like the following: #ifndef BOOST_PARAMETER_RANDOM_EXAMPLE_HPP #define BOOST_PARAMETER_RANDOM_EXAMPLE_HPP #include <boost/type_traits/remove_const.hpp> #include <boost/random/uniform_int.hpp> #include <boost/random/variate_generator.hpp> #include <boost/parameter.hpp> namespace example { BOOST_PARAMETER_KEYWORD(tag, rng_engine) BOOST_PARAMETER_KEYWORD(tag, min) BOOST_PARAMETER_KEYWORD(tag, max) BOOST_PARAMETER_KEYWORD(tag, factor) BOOST_PARAMETER_KEYWORD(tag, addend) struct foo_parameters : boost::parameter::parameters< boost::parameter::required<tag::rng_engine> , boost::parameter::required<tag::min> , boost::parameter::required<tag::max> , boost::parameter::optional<tag::factor> , boost::parameter::optional<tag::addend> > { }; BOOST_PARAMETER_FUN(unsigned int, foo, 3, 5, foo_parameters) { typedef typename boost::remove_const< typename boost::parameter::binding< Params , tag::rng_engine >::type >::type RNGEngine; typedef boost::uniform_int<unsigned int> RNGDist; typedef boost::variate_generator<RNGEngine, RNGDist> RNG; RNGEngine rng_engine = p[example::rng_engine]; RNG rng(rng_engine, RNGDist(p[min], p[max])); return rng() * p[factor | 10] + p[addend | 5]; } } // namespace test #endif // BOOST_PARAMETER_RANDOM_EXAMPLE_HPP The following snippet would then exemplify typical user code: #include <iostream> #include <boost/ref.hpp> #include <boost/random/mersenne_twister.hpp> #include "boost_parameter_random_example.hpp" int main() { boost::mt19937 rng; std::cout << "Named: " << example::foo( example::rng_engine = rng , example::min = 12 , example::max = 24 ) << std::endl; // Ok std::cout << "Unnamed: "; std::cout << example::foo(rng, 12, 24); // error std::cout << std::endl; return 0; } MinGW reports: 'static const T& boost::random::detail::ptr_helper<T&>::ref(const T&) [with T = const boost::mt19937]' and 'static T& boost::random::detail::ptr_helper<T&>::ref(T&) [with T = const boost::mt19937]' cannot be overloaded When I wrap boost::ref around rng, the program runs fine. I'm curious as to why I get this error only when specifying positional arguments. Have I run afoul of something fundamental, such as the forwarding problem? Cromwell D. Enage __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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