I would know if there is a way to pass arguments using std::mem_fun ?
I want to precise that I can have as much arguments as possible and a lot of member functions.
The problem is that I'm on an old standard and I'm looking for a full stl way so boost isn't allowed as answer even if I know I could do it easily =/
Here is a little illustration of how I wanna use it :
#include <list>
#include <algorithm>
// Class declaration
//
struct Interface {
virtual void run() = 0;
virtual void do_something(int) = 0;
virtual void do_func(int, int) = 0;
};
struct A : public Interface {
void run() { cout << "Class A : run" << endl; }
void do_something(int foo) { cout << "Class A : " << foo << endl; }
void do_func(int foo, int bar) { cout << "Class A : " << foo << " " << bar << endl; }
};
struct B : public Interface {
void run() { cout << "Class B : run" << endl; }
void do_something(int foo) { cout << "Class B : " << foo << endl; }
void do_func(int foo, int bar) { cout << "Class B : " << foo << " " << bar << endl; }
};
// Main
//
int main() {
// Create A and B
A a;
B b;
// Insert it inside a list
std::list<Interface *> list;
list.push_back(&a);
list.push_back(&b);
// This works
std::for_each(list.begin(), list.end(), std::mem_fun(&Interface::run));
// But how to give arguments for those member funcs ?
std::for_each(list.begin(), list.end(), std::mem_fun(&Interface::do_something));
std::for_each(list.begin(), list.end(), std::mem_fun(&Interface::do_func));
return 0;
}
Use std::bind
via std::bind1st
and std::bind2nd
std::for_each(list.begin(), list.end(),
std::bind2nd(std::mem_fun(&Interface::do_something),1) // because 1st is this
);
Unfortunately, the standard does not help for the two arguments version and you need to write your own:
struct MyFunctor
{
void (Interface::*func)(int,int);
int a;
int b;
MyFunctor(void (Interface::*f)(int,int), int a, int b): func(f), a(a), b(b) {}
void operator()(Interface* i){ (i->*func)(a,b);}
};
std::for_each(list.begin(), list.end(),
MyFunctor(&Interface::do_func, 1, 2)
);
The original answer was good back in 2012 when Lambda's had just been added to the standard and few compilers were C++11 compliant yet. Now 8 years later most compilers are C++11 compliant and we can use this to make these things much simpler.
// Binding 1 parameter
std::for_each(list.begin(), list.end(),
[](auto act){act->do_something(1);})
// Binding 2 parameters
std::for_each(list.begin(), list.end(),
[](auto act){act->do_func(1, 2);})
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