AnyValue

public struct AnyValue
extension AnyValue: CustomStringConvertible, CustomDebugStringConvertible

A wrapper for a value of any type, with efficient access and inline storage of bounded size for small values.

Existential types such as Any provide the storage characteristics of AnyValue, but many operations on existentials optimize poorly, so AnyValue may be needed to achieve efficient access.

Using enums and no existential, it is possible to build such storage for:

  • types that are trivially copiable (such as Int), or
  • collections of elements with the inline storage being (roughly) a multiple of the element size. You might consider using the enum approach where applicable.
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  • Creates an instance that stores x.

    Postcondition

    where a is the created instance, a.storedType == T.self, and a[T.self] is equivalent to x.

    Declaration

    Swift

    public init<T>(_ x: T)
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  • The type of the value stored in self.

    Declaration

    Swift

    public var storedType: Any.Type { get }
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  • Accesses the T stored in self.

    Requires

    storedType == T.self.

    Declaration

    Swift

    @inline(__always)
public subscript<T>(_: Type<T>) -> T { get set }
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  • Unsafely accesses the T stored in self.

    Requires

    storedType == T.self.

    Declaration

    Swift

    @inline(__always)
public subscript<T>(unsafelyAssuming _: Type<T>) -> T { get set }
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  • Stores x in self.

    This may be more efficient than self = AnyValue(x) because it uses the same allocated buffer when possible for large types.

    Declaration

    Swift

    public mutating func store<T>(_ x: T)
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  • The stored value.

    This property can be useful for interoperability with the rest of Swift, especially when you don’t know the full dynamic type of the stored value.

    Declaration

    Swift

    public var asAny: Any { get }
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  • A textual representation of this instance.

    Declaration

    Swift

    public var description: String { get }
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  • A string, suitable for debugging, that represents the instance.

    Declaration

    Swift

    public var debugDescription: String { get }
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