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[asio] How do you fake the time for boost timers?
by Josh Quigley 20 Jan '13

20 Jan '13

(For those interested this question is also at http://stackoverflow.com/questions/14191855/how-do-you-fake-the-time-for-bo… ) Hi all, If possible, how do you fake the time for the purpose of triggering boost timers in a unit test? For example, is it possible to achieve something like the following: #include <iostream>#include <boost/asio.hpp>#include <boost/date_time/posix_time/posix_time.hpp> void print(const boost::system::error_code& /*e*/){ std::cout << "Hello, world!\n";} int main(){ boost::asio::io_service io; // Possibly another class needed here, or a way of setting the clock to be fake boost::asio::deadline_timer t(io, boost::posix_time::hours(24)); t.async_wait(&print); io.poll(); // Nothing should happen - no handlers ready // PSEUDO-CODE below of what I'd like to happen, jump ahead 24 hours io.set_time(io.get_time() + boost::posix_time::hours(24)); io.poll(); // The timer should go off return 0;} I'm aware I could wrap the io_service and deadline_timer in a wrapper and write my own test implementation, thus providing the real and test version to the production code I'm trying to test. What I'm hoping is the boost framework allows a way to create an io service that is related to a fake clock rather than the system time, meaning I don't need to create my own wrappers. I should also point out that the docs indicate providing something like my own WaitableTimerService orTimerService may be the way to go, but I can't see which one (if any) is responsible for providing the clock. Any tips appreciated! Josh.

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[MultiIndex] more on key extractor issues
by John M. Dlugosz 19 Jan '13

19 Jan '13

I think my problem stems from the use of 'const' in the underlying element with pointer traversal. Consider: typedef multi_index_container< shared_ptr< const ItemBase >, indexed_by< ordered_non_unique< member< const ItemBase, // <<--- here const unsigned long, // <<--- here &ItemBase::some_member > >, // ordered_non_unique ordered_unique< tag<S2>, member< ItemBase, const S2, &ItemBase::another_member > > // ordered_unique > // indexed_by > ItemList_type_base; I added the two 'const' occurrences on the lines marked with "here", and it behaved better. I think it worked with the second index originally because one of those const's was originally there. The member in question was originally const, so I had included const as part of the type there. Basically, what is happening on Windows VS10 is: template<class Class,typename Type,Type Class::*PtrToMember> struct non_const_member_base { typedef Type result_type; template<typename ChainedPtr> #if !defined(BOOST_NO_SFINAE) typename disable_if< is_convertible<const ChainedPtr&,const Class&>,Type&>::type #else Type& #endif operator()(const ChainedPtr& x)const { return operator()(*x); // <<-- HERE } const Type& operator()(const Class& x,int=0)const { return x.*PtrToMember; } Type& operator()(Class& x)const { return x.*PtrToMember; } }; The ChainedPointer form unpeels a const-qualified type with (*x), and that matches the middle form, not the third. But the signature on the first form is looking for Type, which is exactly what I put in the member<...> index directive. So, I suggest that a quick note concerning constant types inside chained pointer following could be added to the tutorial section. Meanwhile, a stranger problem occured on the Mac, using the Clang compiler. I got an error saying that none of the operator() candidates were viable for overloading, with the error indicating that the type of thing being passed in was the shared_ptr<const ItemBase>. It said the first form was ignored because of instantiation failure, but that is exactly contrary to the disable_if. I'm suspecting that the is_convertable itself somehow choked rather than producing false_type...? Naturally none of the other overloads matched, as a shared_ptr<T> cannot be passed where a T is expected, and that's exactly when the first form would be switched in! —John

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[MultiIndex] is ordered_non_unique stable?
by John M. Dlugosz 19 Jan '13

19 Jan '13

Will equivalent elements in a ordered_non_unique index be "stable" and maintain their relative ordering based on the order in which they were inserted? Or do I need to use a complex key, adding my own sequence number, to ensure the desired ordering? —John

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Re: [Boost-users] [serialization] Serializing derived
by Brown, Matt 18 Jan '13

18 Jan '13

Hi Daniel, You may have already considered this option, but what if you were to require a template argument for which the user could pass a serialization behavior class ... much like an allocator for STL containers. I.E. YOUR CODE: template <typename T, typename serialize_T> struct container { void serialize(unsigned version) {serialize_T::do(data, version);} virtual ~container() = default; T data; }; USER'S CODE: struct my_serialize { static void do(SOME_TYPE data, unsigned version) {<user does what's needed here>} }; typedef container<SOME_TYPE, my_serialize> my_container; Maybe of some help to you? -- Matt ________________________________ This e-mail contains privileged and confidential information intended for the use of the addressees named above. If you are not the intended recipient of this e-mail, you are hereby notified that you must not disseminate, copy or take any action in respect of any information contained in it. If you have received this e-mail in error, please notify the sender immediately by e-mail and immediately destroy this e-mail and its attachments.

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[Phoenix][Range] What's wrong here...
by Robert Jones 18 Jan '13

18 Jan '13

Hi All Can anyone tell me what's wrong with this? The error message is so huge I'm a bit overwhelmed! I suspect type deduction is failing, but none of my efforts to correct it have worked. Thx, Rob. #include <boost/phoenix/bind.hpp> #include <boost/phoenix/bind/bind_function_object.hpp> #include <boost/phoenix/core.hpp> #include <boost/phoenix/operator.hpp> #include <boost/range/adaptor/adjacent_filtered.hpp> #include <boost/range/algorithm/for_each.hpp> void f( const double & ) { } template <class Compare> void sorted( Compare cmp ) { using boost::adaptors::adjacent_filtered; using boost::phoenix::arg_names::_1; using boost::phoenix::arg_names::_2; std::vector<double> input = { 0.0, 1.0, 2.0, 3.0, 4.0 }; // Ok for_each( input | adjacent_filtered( cmp ) , f ); // Not Ok for_each( input | adjacent_filtered( bind( cmp, _1, _2 ) ) , f ); } int main( ) { sorted( std::less<double>( ) ); }

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[serialization] Serializing derived template class via base pointer
by Daniel Mitchell 18 Jan '13

18 Jan '13

Hi everyone, has any progress has been made on a general solution for this problem? Given classes like these, struct base { template<typename Archive> void serialize(Archive& ar, unsigned version) { } virtual ~base() = default; }; template<typename T> struct derived : base { template<typename Archive> void serialize(Archive& ar, unsigned version) { ar & data; } T data; }; is it possible to serialize the derived type (with T unknown) via a base pointer? Sticking a call to register_type<derived> in derived::serialize doesn't seem to do it.

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[MultiIndex] strange problem with simple use of member key extractor
by John M. Dlugosz 18 Jan '13

18 Jan '13

namespace bmi = boost::multi_index; .... bmi::ordered_non_unique< bmi::member< ItemBase, unsigned, &ItemBase::my_member > >, // ordered_non_unique .... I'm getting a compiler error on VS10 from template<class Class,typename Type,Type Class::*PtrToMember> struct non_const_member_base { .... Type& operator()(const ChainedPtr& x)const { return operator()(*x); } boost/multi_index/member.hpp(105): error C2440: 'return' : cannot convert from 'const unsigned int' to 'unsigned int &' It also tells me that the ChainedPtr is a shared_ptr to a const ItemBase, and I can see that _none_ of the operator()'s in that class return a non-reference. But if the compiler is already thinking ref-becomes-lvalue and leaves that out, the next form const Type& operator()(const Class& x,int=0)const { return x.*PtrToMember; } is a perfect match to *x and so I expect the return value to be in fact const (because the object being dereferencd was const) Any idea what's going on here, and what I might do about it? Our project is using Boost 1.49, though I didn't see anything in the release notes about changes to MultiIndex in later releases. —John

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[BGL] Limited depth search without O(number_of_verices) complexity?
by Ilja Honkonen 18 Jan '13

18 Jan '13

Hello Is it possible to do a limited depth depth first search without using O(N) additional memory? The following code seems to visit only a part of the graph but it still requires O(N) memory for the external color map. Could that be avoided with an internal color map? I didn't manage to get depth_first_visit(...) to use an internal color map. Would the solution work also with other graph types besides <vecS, vecS, ...>? #include <iostream> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/depth_first_search.hpp> using namespace std; using namespace boost; struct custom_dfs_visitor : public default_dfs_visitor { template < typename Vertex, typename Graph > void discover_vertex(const Vertex& v, const Graph& g) const { cout << v << endl; } }; struct Terminator { template<class Vertex, class Graph> bool operator()(const Vertex& v, const Graph& g) { return v > 2; } }; int main() { typedef adjacency_list< vecS, vecS, undirectedS > Graph_T; Graph_T g(6); add_edge(0, 1, g); add_edge(1, 2, g); add_edge(2, 3, g); add_edge(3, 4, g); add_edge(4, 5, g); vector<default_color_type> color_map(num_vertices(g)); depth_first_visit( g, vertex(0, g), custom_dfs_visitor(), make_iterator_property_map( color_map.begin(), get(vertex_index, g), color_map[0] ), Terminator() ); cout << "size: " << color_map.size() << endl; return 0; } Thanks Ilja

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[MultiIndex] stable? Please help
by John M. Dlugosz 18 Jan '13

18 Jan '13

earlier I posted a question as to whether a non-unique index in MultiIndex is "stable" with regards to insertion order. Can anyone speak to this?

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boost::range RangeConcept problem.
by Hurcan Solter 17 Jan '13

17 Jan '13

The following snippet is the mock-up of the problem I am having in order to be able to reproduce. -------------------------------------------------------------------------------- #include <iostream> #include <boost/range.hpp> #include <boost/range/adaptors.hpp> #include <boost/range/algorithm.hpp> #include <boost/bind.hpp> #include <boost/assign.hpp> using namespace boost::assign; struct wxSize { wxSize(int height=0,int width=0):m_height(height),m_width(width) { } int GetWidth() const {return m_width;} int m_height; int m_width; }; class wxWindowBase { public: wxSize GetTextExtent(const std::string val) { return wxSize(0,val.length()); } void DoLayout(std::vector<std::string> m_FilteredItems) { using boost::adaptors::transformed; wxSize longest = *boost::max_element(m_FilteredItems | transformed(boost::bind(&wxWindowBase::GetTextExtent,this,_1)), boost::bind(std::less<int>(),boost::bind(&wxSize::GetWidth,_1),boost::bind(&wxSize::GetWidth,_2))); std::cout <<longest.GetWidth(); } }; int main() { std::vector<std::string> input; input += "o","two","threexxx","four"; wxWindowBase window; window.DoLayout(input); } ----------------------------------------------------------------------------------------- The above code fails to compile on GCC4.7.2 and MSVC10 although it compiles and runs fine on clang3.3 >From what I understand ,transformed returns a Single Pass Range and max_element expects a ForwardRange and that's the gist of the problem.But it works for something like max_element(someint_vector | transformed(doubleit()),std::less<int>()); without problems. Is there a elegant way to achieve what I am trying to without using a intermediate container? Thanks in advance..

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