Add EIP-7495 specifications for StableContainer[N] and Profile[B]
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This introduces EIP-7495 SSZ types to improve forward compatibility: - https://eips.ethereum.org/EIPS/eip-7495
ensi321
reviewed
Jun 7, 2024
| @@ -203,6 +281,8 @@ Deserialization can be implemented using a recursive algorithm. The deserializat | |||
| * Using the first offset, we can compute the length of the list (divide by `BYTES_PER_LENGTH_OFFSET`), as it gives us the total number of bytes in the offset data. | |||
| * The size of each object in the vector/list can be inferred from the difference of two offsets. To get the size of the last object, the total number of bytes has to be known (it is not generally possible to deserialize an SSZ object of unknown length) | |||
| * Containers follow the same principles as vectors, with the difference that there may be fixed-size objects in a container as well. This means the `fixed_parts` data will contain offsets as well as fixed-size objects. | |||
| * `StableContainer[N]`: The serialized data will start with a `Bitvector[N]`. That value MUST be validated: All extra bits in the `Bitvector[N]` that exceed the number of fields MUST be `False`. The rest of the data is deserialized same as a regular SSZ `Container`, consulting the `Bitvector[N]` to determine which fields are present in the data. Absent fields are skipped during deserialization and assigned `None` values. | |||
| * `Profile[B]`: If there are optional fields in `Profile[B]`, the serialized data will start with a `Bitvector[O]` with `O` set to the total number of optional fields. The rest of the data is deserialized same as a regular SSZ `Container`, consulting the `Bitvector[O]` to determine which fields are present in the data. Absent fields are skipped during deserialization and assigned `None` values. | |||
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Here it implies "in the case there is no optional field, deserialize like a regular container". Is it worth pointing this out more explicitly?
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I think it's quite explicit already, as the Bitvector[O] is only there "if there are optional fields".
tbenr
approved these changes
Jul 17, 2024
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This introduces EIP-7495 SSZ types to improve forward compatibility: