Note: This paper was adopted into draft C++14 on Saturday at the Bristol UK ISO C++ meeting.

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Document number: N3655

Date: 2013-04-18

TransformationTraits Redux, v2

by Walter Brown

NOTE: Section 4 was not adopted.

Excerpt:

... We therefore propose to add a set of template aliases for the library’s TransformationTraits in order to reduce the programmer burden of expressing this far more common case. Note, in the following rewrite of the above example, the absence of any typename keyword, as well as the absence of any ::type suffix, thus condensing the statement from 3 to 2 lines of code:

template< class T > using reference_t
  = conditional_t< is_reference<T>::value, T, add_lvalue_reference_t<T> >;