BC-DCBOR TypeScript Library - v1.0.0-alpha.13
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    Interface CborTagged

    Interface for types that have associated CBOR tags.

    In CBOR, tags provide semantic information about how to interpret data items. This interface defines which CBOR tag(s) are associated with a particular TypeScript type.

    Implementing this interface is a prerequisite for implementing CborTaggedEncodable and CborTaggedDecodable.

    The cborTags() method returns an array of tags, enabling support for backward compatibility with older tag versions:

    • When encoding: Only the first tag in the array is used for serialization
    • When decoding: Any of the tags in the array will be accepted

    This design solves several real-world problems:

    1. IANA Registration Simplification: If you initially choose a tag in the Specification Required range (24-32767) and later want to move to the simpler First Come, First Served range (32768+), you can migrate while maintaining compatibility with existing data.

    2. Protocol Evolution: As your protocol evolves, you can introduce new preferred tags while still supporting data encoded with older tags.

    3. Versioning: Different tags can represent different versions of your data format while sharing the same TypeScript type for handling.

    // Single tag
    class Date implements CborTagged {
      cborTags(): Tag[] {
        return [createTag(1, 'date')];
      }
    }

    // Multiple tags for backward compatibility
    class Seed implements CborTagged {
      cborTags(): Tag[] {
        return [
          createTag(40300, 'seed'),  // Primary tag (used for encoding)
          createTag(300, 'seed-legacy'), // Legacy tag (accepted for decoding)
        ];
      }
    }
    interface CborTagged {
        cborTags(): Tag[];
    }

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    cborTags

    Methods

    • Returns the CBOR tags associated with this type.

      This method should return an array of tags in order of preference:

      • The first tag in the array is the "preferred" tag and will be used when encoding values of this type via CborTaggedEncodable.taggedCbor().

      • All tags in the array are considered equivalent for decoding. When CborTaggedDecodable.fromTaggedCbor() is called, any tag in this array will be accepted as valid for this type.

      This design enables backward compatibility: you can introduce a new tag (placed first in the array) while still supporting older tags for decoding.

      For standard CBOR tags, you can use predefined tag constants from the tags module, or create custom tags with createTag().

      Returns Tag[]

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