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Document number: N3761

Date: 2013-08-29

Proposing type_at<>

by Sean Middleditch

Excerpt:

The standard library currently is missing utility templates for extracting types from a variadic template type list, requiring users to instantiate a std::tuple<> in order to extract a type from a specific position within a variadic template type list.

A simple library addition can make certain recurisve uses of variadic templates easier and not dependent on the unrelated concept of a tuple.

This proposal is a pure library addition with no language changes or backwards compatibility regressions. The proposed language for value_at<> depends on N3638, though it could be written without this requirement using type_at<> instead.