Então, eu tenho problema com o std :: map, lambda e algoritmo stl (remove_if). Na verdade, o mesmo código com std :: list ou std :: vector funciona bem.

Meu exemplo de teste:

#include <map>
#include <iostream>
#include <algorithm>

struct Foo
{
    Foo() : _id(0) {}
    Foo(int id) : _id(id)
    {

    }

    int _id;    
};
typedef std::map<int, Foo> FooMap;


int main()
{
    FooMap m;
    for (int i = 0; i < 10; ++i)
        m[i + 100] = Foo(i);

    int removeId = 6;
    // <<< Error here >>>
    std::remove_if(m.begin(), m.end(), [=](const FooMap::value_type & item) { return item.second._id == removeId ;} ); 

    for (auto & item : m )
        std::cout << item.first << " = " << item.second._id << "\n";    

    return 0;
}

Mensagem de erro

In file included from /usr/include/c++/4.6/utility:71:0,
                 from /usr/include/c++/4.6/algorithm:61,
                 from main.cxx:1:
/usr/include/c++/4.6/bits/stl_pair.h: In member function ‘std::pair<_T1, _T2>& std::pair<_T1, _T2>::operator=(std::pair<_T1, _T2>&&) [with _T1 = const int, _T2 = Foo, std::pair<_T1, _T2> = std::pair<const int, Foo>]’:
/usr/include/c++/4.6/bits/stl_algo.h:1149:13:   instantiated from ‘_FIter std::remove_if(_FIter, _FIter, _Predicate) [with _FIter = std::_Rb_tree_iterator<std::pair<const int, Foo> >, _Predicate = main()::<lambda(const value_type&)>]’
main.cxx:33:114:   instantiated from here
/usr/include/c++/4.6/bits/stl_pair.h:156:2: error: assignment of read-only member ‘std::pair<const int, Foo>::first’

Eu não entendo o que há de errado aqui. Então, fico feliz em ler alguns conselhos / instruções sobre o assunto. Meu objetivo - use o novo estilo lambda com std :: map e algoritmos, como remove_if.

g ++ 4.6, -std = c ++ 0x.