c++ - How to use typename instead of typedef? -

i have following code snippet:

template <class t> int foo(t (*f)()) {     typedef t (*func)();     typedef functor<t, func> f; //this line       // ... }

as can see, use typedef function pointer (func), want remove simplify code. tried this:

template <class t> int foo(t (*f)()) {     typedef functor<t, typename f> f;      // ... }

but doesn't compile. right way to spell full typedef f in single line?

just put in actual type of f:

typedef functor<t, t(*)()> f;

or use decltype:

typedef functor<t, decltype(f)> f;

or write alias such thing:

template <typename t> using returnt = t(*)();  template <typename t> int foo(returnt<t> f) {     using f = functor<t, returnt<t>>;     // ... }

Call