Re: [Boost-users] [Function] Comparing function objects withstd::find

Christian Larsen:

int main() { typedef function Listener;

Listener a = listenerA; Listener b = listenerB;

bool equal;

// None of these compile: equal = (a == b); equal = function_equal(a, b); equal = a.contains(b); equal = a.contains(a);

return 0; }

As you've seen, 'a' contains listenerA. It's not possible to compare two boost::function objects for equality. Boost.Signals solves the 'remove' problem by returning a dedicated token from 'add' (boost::connection in its case) which you can then pass to 'remove'.