arene::base::type_identity< T > Class Template Reference

Polyfill of std::type_identity added in C++20. More...

Public Types
using	type = T
	an alias for T

Detailed Description

template<typename T>
class arene::base::type_identity< T >

Polyfill of std::type_identity added in C++20.

Template Parameters

T	The type to preserve

Typically used to prevent parameters from being deduced in order to avoid ambiguities in type-deduction.

Can also be used as the identity metafunction in some template metaprogramming expressions.

For example:

/// @brief A function that takes two parameters of the same type
/// @tparam T The type of the arguments
template <typename T>
void foo(T, T);
 
/// @brief A function that takes two parameters of the same type, but only uses the first for type deduction
/// @tparam T The type of the arguments
template <typename T>
void bar(T, arene::base::type_identity_t<T>);
 
void example() {
  // foo(1, 2u);  // error: Ambiguous what T should deduce to.
  foo(1u, 2u);  // OK, T is deduced to unsigned
  bar(1, 2u);   // Ok. T is deduced to type of first argument only (i.e. int)
}

Member Typedef Documentation

type

template<typename T>

using arene::base::type_identity< T >::type = T

an alias for T

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The documentation for this class was generated from the following file:

• arene/base/type_traits/type_identity.hpp