Generable(description:representNilExplicitlyInGeneratedContent:)

Declaration

@attached(extension, conformances: Generable, names: named(init(_:)), named(generatedContent)) @attached(member, names: arbitrary) macro Generable(description: String? = nil, representNilExplicitlyInGeneratedContent: Bool)

Overview

You can apply this macro to structures and enumerations.

@Generable(representNilExplicitlyInGeneratedContent: true)
struct Character {
  @Guide(description: "A short title")
  let title: String

  @Guide(description: "An optional short subtitle for the novel")
  let subtitle: String?

  @Guide(description: "The genre of the novel")
  let genre: Genre
}

@Generable
enum Genre {
  case fiction
  case nonFiction
}

The representNilExplicitlyInGeneratedContent argument controls how the model represents nil properties. When false, the model will omit nil properties from the generated content, so no property will be present. When true, the model will produce a property, but its value will be GeneratedContent.Kind.null.

// representNilExplicitlyInGeneratedContent: false
let content = GeneratedContent(properties: [:])

// representNilExplicitlyInGeneratedContent: true
let content = GeneratedContent(properties: ["foo": nil])

Controlling this behavior can be important when interfacing with external systems, using custom adapters, or working with one-shot examples that contain explicitly encoded nils.

See Also

Defining a generable type

• Generable(description:)