=====typename=====

=== Specifying Type Parameters To Templates ===

In [[template]] argument lists [[typename]] can be used interchangeably with [[class]] to indicate type parameters.  Although there is no difference to the compiler, Alexandrescu recommends using [[class]] when the template argument is expected to be a [[class]] or [[struct]], and [[typename]] for other classes of types.  This is purely to encourage source readability.

=== Disambiguating Dependent Names ===

The [[typename]] keyword is also used to indicate that a [[dependent name|dependent name]] in a template definition refers to a type.

<code>
struct Foo {
  typedef int Type;
};

template<class T>
struct Bar {
  typedef typename T::Type BarType; // In a typedef
  void baz() {
     typename T::Type instance;     // In a declaration
  }
};

typedef Bar<Foo> FooBar;
</code>


Related Topics: [[class]], [[template]]