Hi! the std::find_if function takes as it's third parameter an unary predicate function or function object which evaluates the condition. To implement this you can write your comparison function looking like: template<class FunctionType> struct compare_functions { compare_functions(FunctionType f) : func_(f) {} template<class RefObj> bool operator()(RefObj r)const { return func_==r; //boost::reference_wrapper<T> has an operator T& which is called implicitly } private: FunctionType func_; }; modifications in your code: void remove(boost::function<void (int v)> fun) { std::list<boost::function<void (int v)> >::iterator iter; //IMPLEMENTATION std::find_if(fun_list.begin(), fun_list.end(), compare_functions(fun)); if(iter != fun_list.end()) fun_list.erase(iter); } You could also skip the compare_functions implementation and use boost::lambda and placeholder library to write you code like this: std::find_if(fun_list.begin(), fun_list.end(), _1==fun); With Kind Regards, Ovanes Markarian On Mon, March 12, 2007 09:48, misiu wrote:

Hello,

Could you please tell me how to compare two boost::function objects packet with boost::ref. I have container which has boost::function elements and to add elements is not a problem but to remove particular one I don't know how to do that (compare two boost:ref-s). The problem is shown in the code below.

Regards, Bartek

//code

#include <iostream> #include <list> #include <boost/ref.hpp> #include <boost/function.hpp>

struct test{ int a; void operator() (int aa) { a += aa; } };

struct function_list { std::list<boost::function<void (int v)> > fun_list;

void add(boost::function<void (int v)> fun) { fun_list.push_back(fun); }

void remove(boost::function<void (int v)> fun) { std::list<boost::function<void (int v)> >::iterator iter;

//HOW TO IMPLEMETN THIS FIND_IF? //std::find_if(fun_list.begin(), fun_list.end(), MISSING_PART);

if(iter != fun_list.end()) fun_list.erase(iter); } };

int main(int argc, char **argv) {

test a, b; function_list f;

f.add(boost::ref(a)); f.add(boost::ref(b)); //DOES NOT WORK f.remove(boost::ref(a)); }

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