The __tr1__tuple__ type provides a default constructor, a constructor that takes initializers for all of its elements, a copy constructor, and a converting copy constructor. The details of the various constructors are described in this section.
[heading Specification]
[variablelist Notation
[[`T1 ... TN`, `U1 ... UN`][Tuple element types]]
[[`P1 ... PN`] [Parameter types]]
[[`Ti`, `Ui`] [The type of the `i`th element of a tuple]]
[[`Pi`] [The type of the `i`th parameter]]
]
tuple();
[*Requirements]: Each `Ti` is default constructable.
[*Semantics]: Default initializes each element of the tuple.
tuple(P1,P2,...,PN);
[*Requirements]: Each `Pi` is `Ti` if `Ti` is a reference type, `const Ti&` otherwise.
[*Semantics]: Copy initializes each element with the corresponding parameter.
tuple(const tuple& t);
[*Requirements]: Each `Ti` should be copy constructable.
[*Semantics]: Copy constructs each element of `*this` with the corresponding element of `t`.
[*Requirements]: Each `Ti` shall be constructible from the corresponding `Ui`.
[*Semantics]: Constructs each element of `*this` with the corresponding element of `t`.
[endsect]
[section Tuple creation functions]
[heading Description]
TR1 describes 2 utility functions for creating __tr1__tuple__s. `make_tuple` builds a tuple out of it's argument list, and `tie` builds a tuple of references to it's arguments. The details of these creation functions are described in this section.
[*Returns]: tuple<T1&, T2&, ..., TN&>(t1, t2, ..., tN). When argument `ti` is `ignore`, assigning any value to the corresponding tuple element has has no effect.
[endsect]
[section Tuple helper classes]
[heading Description]
The __tr1__tuple__ provides 2 helper traits, for compile time access to the tuple size, and the element types.
[heading Specification]
tuple_size<T>::value
[*Requires]: `T` is any fusion sequence type, including `tuple`.
[*Type]: __mpl_integral_constant__
[*Value]: The number of elements in the sequence. Equivalent to `__result_of_size__<T>::type`.
tuple_element<I, T>::type
[*Requires]: `T` is any fusion sequence type, including `tuple`. `0 <= I < N` or the program is ill formed.
[*Value]: The type of the `I`th element of `T`. Equivalent to `__result_of_value_at__<I,T>::type`.
[endsect]
[section Element access]
[heading Description]
The __tr1__tuple__ provides the `get` function to provide access to it's elements by zero based numeric index.