boost-bind

问题 I want to use boost::bind to create a boost::function inserting a new key-value pair into a boost::unoredered_map but I got few compilation errors. typedef boost::unordered_map< std::string, std::string > dict_type; inline void insert( const std::string& key, const std::string& value ){ typedef std::pair<dict_type::iterator, bool> out_type; dict_type::value_type to_insert(key,value); boost::function<void()> f = boost::bind<out_type>( &dict_type::insert ,obj_ ,boost::cref(to_insert) ); } The

问题 I'm trying to reference a member of a (yet) unknown instance from within a boost::spirit rule definitions' action, so in pseudocode, instead of double_[ref(rN) = _1] I'm looking for something like X** ppx; double_[ref(&X::rN, ppx) = _1] A workaround for it could be a simple "semantic action" with a parameter which knows the instance and would be able to write to it, like qi::rule<Iterator, Skipper> start; my_grammar(DataContext*& dataContext) : my_grammar::base_type(start) , execContext

问题 I'm trying to reference a member of a (yet) unknown instance from within a boost::spirit rule definitions' action, so in pseudocode, instead of double_[ref(rN) = _1] I'm looking for something like X** ppx; double_[ref(&X::rN, ppx) = _1] A workaround for it could be a simple "semantic action" with a parameter which knows the instance and would be able to write to it, like qi::rule<Iterator, Skipper> start; my_grammar(DataContext*& dataContext) : my_grammar::base_type(start) , execContext

问题 #include <QtCore/QCoreApplication> #include <boost/bind.hpp> #include <boost/function.hpp> class button { public: boost::function<void()> onClick; boost::function<void(int ,double )> onClick2; }; class player { public: void play(int i,double o){} void stop(){} }; button playButton, stopButton; player thePlayer; void connect() { //error C2298: 'return' : illegal operation on pointer to member function expression playButton.onClick2 = boost::bind(&player::play, &thePlayer); stopButton.onClick =

问题 We're getting this compile error followed by many more errors showing attempts to match the subscribe parameters to all possible candidate functions when using boost::bind as a callback for subscribe. error: no matching function for call to ‘ros::NodeHandle::subscribe(const char [18], int, boost::_bi::bind_t<void, void (*)(const geometry_msgs::WrenchStamped_<std::allocator<void> >&, moveit::planning_interface::MoveGroup&), boost::_bi::list2<boost::arg<1>, boost::_bi::value<moveit::planning

问题 I noticed that when passing reference parameters to boost bind, those parameters won't act like references. Instead boost creates another copy of the member and the original passed in variable remains unchanged. When I change the references to pointers, everything works ok. My question is: Is it possible to get references to work, or at least give a compiling error when it tries to use reference parameters? 回答1: The boost documentation for bind suggests that you can use boost::ref and boost:

问题 I noticed that boost::bind, unlike std::bind, can work with overloaded functions when one of these functions doesn't have any parameters. Am I right? Is this documented? #include <boost/bind.hpp> #include <functional> #include <iostream> void foo() { std::cout << "::foo() \n"; } void foo(int) { std::cout << "::foo(int) \n"; } int main() { boost::bind(foo)(); // Ok boost::bind(foo, 0)(); // Ok // std::bind(foo)(); // Error // std::bind(foo, 0)(); // Error } #include <boost/bind.hpp> #include

问题 Suppose I have a function which takes a nullary functor as an argument: void enqueue( boost::function<void()> & functor ); I have another function which takes an int and does something internally: void foo( int a); I would like to nest, but not compose, these together so that I get a functor with the signature: boost::function<void(int)> functor Which when called with a value - say 4 - performs the following: enqueue( boost::bind(&foo, 4) ) My first attempt was the following: boost::function

问题 Recently I discovered that shared_ptr does not have pointer to member operator ->* . I created simple example: template <typename Pointer, typename Function, typename... Args> auto invoke1(Pointer p, Function f, Args... args) -> decltype((p->*f)(args...)) { return (p->*f)(args...); } struct A { void g() { std::cout << "A::g()\n"; } }; int main() { A a; invoke1(&a, &A::g); // works!! std::shared_ptr<A> sa = std::make_shared<A>(); invoke1(sa, &A::g); // compile error!! } Q1: Why is so? Why

问题 I want to save the "binder" of a function to a variable, to use it repetitively in the following code by exploiting its operator overloading facilities. Here is the code that actually does what I want: #include <boost/bind.hpp> #include <vector> #include <algorithm> #include <iostream> class X { int n; public: X(int i):n(i){} int GetN(){return n;} }; int main() { using namespace std; using namespace boost; X arr[] = {X(13),X(-13),X(42),X(13),X(-42)}; vector<X> vec(arr,arr+sizeof(arr)/sizeof(X