How to use boost bind with a member function

Question

The following code causes cl.exe to crash (MS VS2005).
I am trying to use boost bind to create a function to a calls a method of myclass:

#include "stdafx.h" #include <boost/function.hpp> #include <boost/bind.hpp> #include <functional>  class myclass { public:     void fun1()       { printf("fun1()\n");      }     void fun2(int i)  { printf("fun2(%d)\n", i); }      void testit() {         boost::function<void ()>    f1( boost::bind( &myclass::fun1, this ) );         boost::function<void (int)> f2( boost::bind( &myclass::fun2, this ) ); //fails          f1();         f2(111);     } };  int main(int argc, char* argv[]) {     myclass mc;     mc.testit();     return 0; } 

What am I doing wrong?

Answer 1

Use the following instead:

boost::function<void (int)> f2( boost::bind( &myclass::fun2, this, _1 ) ); 

This forwards the first parameter passed to the function object to the function using place-holders - you have to tell Boost.Bind how to handle the parameters. With your expression it would try to interpret it as a member function taking no arguments.
See e.g. here or here for common usage patterns.

Note that VC8s cl.exe regularly crashes on Boost.Bind misuses - if in doubt use a test-case with gcc and you will probably get good hints like the template parameters Bind-internals were instantiated with if you read through the output.