Can I use accumulate to do this?

I just can't get my head around to create a suitable
binary_function that will do this i.e. call a member function
from within accumulate. In fact I rolled my own template.
But I have a terrible feeling of reinventing the wheel.

/
*----------------------------------------------------------------------
*/
#include <vector>
#include <iterator>
#include <iostream>

using namespace std;

template <class I, class V, class Fn1, class Fn2>
V accumulate2(I first, I last, V val, Fn1 op, Fn2 memfn) {
    for (; first != last; ++first)
        val = op(val, memfn(*first));
    return val;
}

struct strange {
    strange(int a, int b) : _a(a), _b(b) {}
    int value() { return _a + 10 * _b; }
    int _a, _b;
};

int main() {
    std::vector<strange> dv;
    dv.push_back(strange(1, 3));
    dv.push_back(strange(4, 6));
    dv.push_back(strange(20, -11));
    cout << accumulate2(dv.begin(), dv.end(),
                                   0, std::plus<int>(),
                                    mem_fun_ref(&strange::value))
           << endl;
}

/
*----------------------------------------------------------------------
*/

I have not yet looked into Boost -- but suggestions
are most welcome.

Regards,
Suman