c++ - using std::transform for calling object's function -

suppose have vector of shared pointers of objects of class a. want collect return values of method a::foo of objects , store them in container, vector. can done std::transform or std::for_each , std::bind or boost function ?

class {    public:   string foo(int p);  };  std::vector<shared_ptr<a>> vec; 

std::transform fine this:

std::vector<std::string> string_vec; const int magic_number = 42; std::transform(std::begin(vec),               std::end(vec),               std::back_inserter(string_vec),               [magic_number](std::shared_ptr<a> a){ return a->foo(magic_number); } ); 

obviously, need figure out int want pass a::foo(int).

in c++03, can replace lambda functor or function:

struct get_foo {   get_foo(int n) : n_(n) {}   bool operator() (std::shared_ptr<a> a) const { return a->foo(n); } private:   int n_; };  const int magic_number = 42; std::vector<std::string> string_vec; std::transform(std::begin(vec),               std::end(vec),               std::back_inserter(string_vec),               get_foo(magic_number));