Exactly as you have written it.
typedef void (Foo::*Bar_t)(std::string &, const std::string&);
Bar_t stringedBar = &Foo::bar<std::string>;
See here for an example.
Question
There is a templated member function in some class Foo
template <typename T>
void Foo::bar(std::string &, const T&);
How to make a make pointer to following specialized variant of this function?
void Foo::bar<std::string>(std::string &, const std::string&);
There is like what I mean
typedef void (Foo::*Bar_t)(std::string &, const std::string&);
Bar_t stringedBar = &Foo::bar<std::string> // ???
Solution
Exactly as you have written it.
typedef void (Foo::*Bar_t)(std::string &, const std::string&);
Bar_t stringedBar = &Foo::bar<std::string>;
See here for an example.