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static constexpr bool | is_null (std::variant< T... > const &value) noexcept |
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static constexpr std::variant< T... > | null ()=delete |
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static bool | is_null (std::variant< T... > const &value) |
| Is value a null?
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static std::variant< T... > | null () |
| Return a null value.
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static constexpr bool | has_null = (nullness<T>::has_null or ...) |
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static constexpr bool | always_null = (nullness<T>::always_null and ...) |
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static bool | has_null |
| Does this type have a null value?
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static bool | always_null |
| Is this type always null?
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◆ null() [1/2]
static std::variant< T... > pqxx::nullness< std::variant< T... >, void >::null |
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staticnodiscard |
Return a null value.
Don't use this in generic code to compare a value and see whether it is null. Some types may have multiple null values which do not compare as equal, or may define a null value which is not equal to anything including itself, like in SQL.
◆ null() [2/2]
template<typename... T>
static constexpr std::variant< T... > pqxx::nullness< std::variant< T... > >::null |
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staticconstexprdelete |
It would be technically possible to have a null
in the case where just one of the types has a null, but it gets complicated and arbitrary.
The documentation for this struct was generated from the following file:
- /builddir/build/BUILD/libpqxx-7.10.0-build/libpqxx-7.10.0/redhat-linux-build/include/pqxx/internal/conversions.hxx