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std::tuple::operator=

From cppreference.com
< cpp‎ | utility‎ | tuple
tuple& operator=( const tuple& other );
(1) (since C++11)
tuple& operator=( tuple&& other ) noexcept(/* see below */);
(2) (since C++11)
template< class... UTypes >
tuple& operator=( const tuple<UTypes...>& other );
(3) (since C++11)
template< class... UTypes >
tuple& operator=( tuple<UTypes...>&& other );
(4) (since C++11)
template< class U1, class U2 >
tuple& operator=( const pair<U1,U2>& p );
(5) (since C++11)
template< class U1, class U2 >
tuple& operator=( pair<U1,U2>&& p );
(6) (since C++11)

Replaces the contents of the tuple with the contents of another tuple or a pair.

1) Copy assignment operator. Replaces each element with a copy of the corresponding element of other.

2) Move assignment operator. Replaces each element with the corresponding element of other using move semantics.

3) For all i, assigns std::get<i>(other) to std::get<i>(*this).

4) For all i, assigns std::forward<Ui>(std::get<i>(other)) to std::get<i>(*this).

5) Assigns p.first to the first element of *this and p.second to the second element of *this.

6) Assigns std::forward<U1>(p.first) to the first element of *this and std::forward<U2>(p.second) to the second element of *this.

The behavior of these functions is undefined unless:

  • For (1), std::is_copy_assignable<T_i>::value is true for all T_i in Types.
  • For (2), std::is_move_assignable<T_i>::value is true for all T_i in Types.
  • For (3), sizeof...(UTypes) == sizeof...(Types) and std::is_assignable<T_i&, const U_i&>::value is true for all corresponding pairs of types T_i in Types and U_i in UTypes.
  • For (4), sizeof...(UTypes) == sizeof...(Types) and std::is_assignable<T_i&, U_i&&>::value is true for all corresponding pairs of types T_i in Types and U_i in UTypes.
  • For (5), sizeof...(Types) == 2 and std::is_assignable<T_0&, const U1&>::value and std::is_assignable<T_1&, const U2&>::value are both true, where T_0 and T_1 are the two types constituting Types.
  • For (6), sizeof...(Types) == 2 and std::is_assignable<T_0&, U1&&>::value and std::is_assignable<T_1&, U2&&>::value are both true, where T_0 and T_1 are the two types constituting Types.
(until C++17)

These functions do not participate in overload resolution (or, for the copy assignment operator, is defined as deleted) if any required assignment operation is invalid or if there is a size mismatch. Specifically:

  • (1) is defined as deleted unless std::is_copy_assignable<T_i>::value is true for all T_i in Types.
  • (2) does not participate in overload resolution unless std::is_move_assignable<T_i>::value is true for all T_i in Types.
  • (3) does not participate in overload resolution unless sizeof...(UTypes) == sizeof...(Types) and std::is_assignable<T_i&, const U_i&>::value is true for all corresponding pairs of types T_i in Types and U_i in UTypes.
  • (4) does not participate in overload resolution unless sizeof...(UTypes) == sizeof...(Types) and std::is_assignable<T_i&, U_i&&>::value is true for all corresponding pairs of types T_i in Types and U_i in UTypes.
  • (5) does not participate in overload resolution unless sizeof...(Types) == 2, std::is_assignable<T_0&, const U1&>::value and std::is_assignable<T_1&, const U2&>::value are both true, where T_0 and T_1 are the two types constituting Types.
  • (6) does not participate in overload resolution unless std::is_assignable<T_0&, U1&&>::value and std::is_assignable<T_1&, U2&&>::value are both true, where T_0 and T_1 are the two types constituting Types.
(since C++17)

Contents

[edit] Parameters

other - tuple to replace the contents of this tuple
p - pair to replace the contents of this 2-tuple

[edit] Return value

*this

[edit] Exceptions

1) (none)

2)
noexcept specification:  
noexcept(

    is_nothrow_move_assignable<T0>::value &&
    is_nothrow_move_assignable<T1>::value &&
    is_nothrow_move_assignable<T2>::value &&
    ...

)

3-6) (none)

[edit] Example

[edit] See also