22 General utilities library [utilities]

22.8 Expected objects [expected]

22.8.7 Partial specialization of expected for void types [expected.void]

22.8.7.6 Observers [expected.void.obs]

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constexpr explicit operator bool() const noexcept; constexpr bool has_value() const noexcept;
1
#
Returns: has_­val.
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constexpr void operator*() const noexcept;
2
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Preconditions: has_­value() is true.
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constexpr void value() const &;
3
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Throws: bad_­expected_­access(error()) if has_­value() is false.
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constexpr void value() &&;
4
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Throws: bad_­expected_­access(std​::​move(error())) if has_­value() is false.
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constexpr const E& error() const & noexcept; constexpr E& error() & noexcept;
5
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Preconditions: has_­value() is false.
6
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Returns: unex.
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constexpr E&& error() && noexcept; constexpr const E&& error() const && noexcept;
7
#
Preconditions: has_­value() is false.
8
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Returns: std​::​move(unex).