I have api function f_api(std::function<void(int)> func)
and now I have my process class
class Func {
public:
void operator()(int i) {
// do some work
}
int operator()(int i, int j) {
// do some other work
}
};
and I want use Func f
f(int i) to pass to f_api to do the work; so I use std::bind
Func f;
std::function<void(int)> func = std::bind(&Func::operator(), &f, std::placeholders::_1);
f_api(func);
but HERE the problem, How can I indicate which Func::operator()()
I want to bind? I can give a member function by its name, but how can I process this when this member function do have several different signed reloading functions? Will std::bind find me the most suitable function to be called? C++ is so complicated.....
the minimal verifiable case:
#include <iostream>
#include <functional>
using namespace std;
class Func {
public:
void operator()(int i) {
// do some work
cout << "i is: " << i << endl;
}
int operator()(int i, int j) {
// do some other work
}
};
void f_api(function<void(int)> f) {
f(3);
}
int main () {
Func f;
std::function<void(int)> func = std::bind(&Func::operator(), &f, std::placeholders::_1);
f_api(func);
return 0;
}
the compiling error:
a.cpp: In function ‘int main()’:
a.cpp:23:91: error: no matching function for call to ‘bind(<unresolved overloaded function type>, Func*, const std::_Placeholder<1>&)’
std::function<void(int)> func = std::bind(&Func::operator(), &f, std::placeholders::_1);
^
a.cpp:23:91: note: candidates are:
In file included from a.cpp:2:0:
/usr/include/c++/4.8/functional:1655:5: note: template<class _Func, class ... _BoundArgs> typename std::_Bind_helper<std::__or_<std::is_integral<typename std::decay<_Tp>::type>, std::is_enum<typename std::decay<_Tp>::type> >::value, _Func, _BoundArgs ...>::type std::bind(_Func&&, _BoundArgs&& ...)
bind(_Func&& __f, _BoundArgs&&... __args)
^
/usr/include/c++/4.8/functional:1655:5: note: template argument deduction/substitution failed:
a.cpp:23:91: note: couldn't deduce template parameter ‘_Func’
std::function<void(int)> func = std::bind(&Func::operator(), &f, std::placeholders::_1);
^
In file included from a.cpp:2:0:
/usr/include/c++/4.8/functional:1682:5: note: template<class _Result, class _Func, class ... _BoundArgs> typename std::_Bindres_helper<_Result, _Func, _BoundArgs>::type std::bind(_Func&&, _BoundArgs&& ...)
bind(_Func&& __f, _BoundArgs&&... __args)
^
/usr/include/c++/4.8/functional:1682:5: note: template argument deduction/substitution failed:
a.cpp:23:91: note: couldn't deduce template parameter ‘_Result’
std::function<void(int)> func = std::bind(&Func::operator(), &f, std::placeholders::_1);
^
And in my case it's a little bit different cause my class Func
cannot be assigned cause one member field of that class is not assignable, so I will get a slightly different error during the compiling time.