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Polymorphism

Zorphy supports sealed and open hierarchies with explicit subtype lists. This page combines sealed_class_example.dart and the domain entities like $$Attachment and $$ChatMessage.

Sealed hierarchy​

@Zorphy(
  generateJson: true,
  explicitSubTypes: [$CreditCard, $PayPal, $BankTransfer],
)
abstract class $$PaymentMethod {
  String get displayName;
  String get processPayment;
}

Concrete types implement the sealed base:

@Zorphy(generateJson: true)
abstract class $CreditCard implements $$PaymentMethod {
  String get cardNumber;
}

Open hierarchy with explicit subtypes​

The domain entities use nonSealed: true to keep the base open while still enabling polymorphic JSON.

@Zorphy(
  generateJson: true,
  explicitSubTypes: [$FileAttachment, $LinkAttachment],
  nonSealed: true,
)
abstract class $$Attachment {
  String get name;
  String get mimeType;
}
@Zorphy(
  generateJson: true,
  explicitSubTypes: [$UserMessage, $AssistantMessage],
  nonSealed: true,
)
abstract class $$ChatMessage {
  String get text;
  ChatMessageRole get role;
}

Why this matters​

  • Safe polymorphic JSON dispatch.
  • Strong typing when switching on subtype.
  • Clear separation between base contracts and concrete classes.