[TSCUtility] Introduce PolymorphicCodable property wrapper #67
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This allows encoding and decoding polymorphic types without writing a bunch of boilerplate code.
| public init(from decoder: Decoder) throws { | ||
| var container = try decoder.unkeyedContainer() | ||
| let typeCode = try container.decode(String.self) | ||
| guard let klass = T.implementations.first(where: { String(reflecting: $0) == typeCode }) else { |
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Should this error or at least assert if there are duplications, to detect programmer error?
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if implementations was a Set then we (eventually) could typeHint -> _typeByName to then T.allowedImplementations.contains(thatTypeByName) to avoid that scanning through. The T we need anyway in order to get the Any.Type as Codable to call decoding on it
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I'm exploring another direction for registering types on Joe's hints... I'll report back once I have something.
More based around "intent" or "permissions" i.e. "this type is intended for crossing network" vs. "this one isnt" etc.
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| /// Allows encoding and decoding known polymorphic types. | ||
| public protocol PolymorphicCodableProtocol: Codable { | ||
| static var implementations: [PolymorphicCodableProtocol.Type] { get } |
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Can't use Set:
Type 'PolymorphicCodableProtocol.Type' does not conform to protocol 'Hashable' and Cannot extend a metatype 'PolymorphicCodableProtocol.Type'
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Since String(reflecting: ) is needed every time implementations is accessed, it might make sense to do a struct representing the (String, Type), and implement a Hashable over it. Then it is going to be Set-compatible. I am sure you've thought of that, just 2c.
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@swift-ci test |
This allows encoding and decoding polymorphic types without writing
a bunch of boilerplate code.