Alexey Nikitin wrote:
I try to compile next code:
===== my_test.cpp ===== #include <functional> #include <boost/bind.hpp>
using namespace std; using namespace boost;
struct my_assign_if { typedef void result_type; template<class T, class P> void operator()(T& dst, T const& src, P const& to_assign) const { if (to_assign()) dst = src; } };
int main() { int a=1, b=0; bind(my_assign_if(), ref(a), 0, _1)(bind(less<int>(), cref(b), 1)); // compiled bind(my_assign_if(), ref(a), 0, bind(less<int>(), cref(b), 1))(); // not compiled return 0; } ==================== and take next errors: [...]
Nested binds are evaluated. You are trying to call: my_assign_if()(a, 0, b < 1); Either change my_assign_if to take a bool argument instead of a predicate, or wrap the nested bind in protect() (available in boost/bind/protect.hpp) to prevent its evaluation and pass it unmodified to my_assign_if.