Answer by moonshadow for When should I use typedef in C++?

Real-world uses of typedef:

• providing friendly aliases for long-winded templated types
• providing friendly aliases for function pointer types

• providing local labels for types, e.g.:

  template<class _T> class A{    typedef _T T;};template<class _T> class B{    void doStuff( _T::T _value );};