Question

I am attempting to map the filter functor with one of the member methods of my class based on the value of an input string.

#include <iostream>
#include <map>
#include <boost/function.hpp>
#include <boost/cstdint.hpp>
#include <boost/assign.hpp>
#include <boost/bind.hpp>

typedef boost::function < bool(std::map<std::string, std::string>, std::string) > MyFilterFunctor;

class MyClass
{
public:
    bool FilterFunction1(std::map<std::string, std::string> myMap, std::string filterValue)
    {
        //do something
        return true;
    }
};

int main() {

    MyFilterFunctor myFilter = boost::bind(&MyClass::FilterFunction1, _1, _2, _3);
    return 0;
}

And my error:

/usr/include/boost/bind/bind.hpp:375:
error: ambiguous overload for ‘operator[]’ in ‘a[boost::_bi::storage3<A1, A2, boost::arg<I> >::a3_ [with A1 = boost::arg<1>, A2 = boost::arg<2>, int I = 3]]’

Edit:
I simplified my example slightly at the suggestion of a proposed answer to my question.
It has been suggested that I need to pass MyClass() as an argument to boost::bind, and this does solve the compilation error in the code segment posted. However, it is not possible for me to do that given my code structure. I would like to know why what I have done is different from this example in the boost::bind documentation:

struct X
{
    int f(int);
}

int main()
{ 
    boost::bind(&X::f, 1);     // error, X::f takes two arguments
    boost::bind(&X::f, _1, 1); // OK
}

Shouldn’t the _1 parameter take care of the implicit ‘this’ which is being suggested I supply explicitly with MyClass()?

Answer 1

This has nothing to do with boost::assign::map_list_of or std::map, the same error can be reproduced simply by this:

MyFilterFunctor mff;
auto bb = boost::bind(&MyClass::FilterFunction1, _1, _2, _3);
mff = bb;

bb requires 3 parameters: a MyClass, a map<string,string> and a string. mff requires 2 parameters, a map<string,string> and a string. The two are clearly incompatible.

Try boost::bind(&MyClass::FilterFunction1, MyClass(), _1, _2)) instead.