[tuple.apply]

# 22 General utilities library [[utilities]](./#utilities)

## 22.4 Tuples [[tuple]](tuple#apply)

### 22.4.6 Calling a function with a tuple of arguments [tuple.apply]

[🔗](#lib:apply)

`template<class F, [tuple-like](tuple.like#concept:tuple-like "22.4.3 Concept tuple-like [tuple.like]") Tuple>
  constexpr apply_result_t<F, Tuple> apply(F&& f, Tuple&& t)
    noexcept(is_nothrow_applicable_v<F, Tuple>);
`

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L2695)

*Effects*: Given the exposition-only function template:namespace std {template<class F, [*tuple-like*](tuple.like#concept:tuple-like "22.4.3 Concept tuple-like [tuple.like]") Tuple, size_t... I>constexpr decltype(auto) *apply-impl*(F&& f, Tuple&& t, index_sequence<I...>) {// *exposition only*return *INVOKE*(std::forward<F>(f), get<I>(std::forward<Tuple>(t))...); // see [[func.require]](func.require "22.10.4 Requirements")}}

Equivalent to:return *apply-impl*(std::forward<F>(f), std::forward<Tuple>(t),
 make_index_sequence<tuple_size_v<remove_reference_t<Tuple>>>{});

[🔗](#lib:make_from_tuple)

`template<class T, [tuple-like](tuple.like#concept:tuple-like "22.4.3 Concept tuple-like [tuple.like]") Tuple>
  constexpr T make_from_tuple(Tuple&& t);
`

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L2721)

*Mandates*: If tuple_size_v<remove_reference_t<Tuple>> is 1,
thenreference_constructs_from_temporary_v<T, decltype(get<0>(declval<Tuple>()))> is false[.](#2.sentence-1)

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L2728)

*Effects*: Given the exposition-only function template:namespace std {template<class T, [*tuple-like*](tuple.like#concept:tuple-like "22.4.3 Concept tuple-like [tuple.like]") Tuple, size_t... I>requires is_constructible_v<T, decltype(get<I>(declval<Tuple>()))...>constexpr T *make-from-tuple-impl*(Tuple&& t, index_sequence<I...>) { // *exposition only*return T(get<I>(std::forward<Tuple>(t))...); }}

Equivalent to:return *make-from-tuple-impl*<T>( std::forward<Tuple>(t),
 make_index_sequence<tuple_size_v<remove_reference_t<Tuple>>>{});

[*Note [1](#note-1)*:

The type of T must be supplied
as an explicit template parameter,
as it cannot be deduced from the argument list[.](#3.sentence-2)

— *end note*]