[Proposal] New Packet ABC

[zxzxwu]

typing.Annotated(introduced in 3.9, but backward compatible by using typing_extensions) allows providing metadata to field annotations, so we could build packets with this feature.

Example:

@dataclass
class HCI_LE_Set_CIG_Parameters_Command(HCI_Command, DataUnit):
    '''
    See Bluetooth spec @ 7.8.97 LE Set CIG Parameters Command
    '''

    cig_id: Annotated[int, FieldSpec(1)]
    sdu_interval_c_to_p: Annotated[int, FieldSpec(3)]
    sdu_interval_p_to_c: Annotated[int, FieldSpec(3)]
    worst_case_sca: Annotated[int, FieldSpec(1)]
    packing: Annotated[int, FieldSpec(1)]
    framing: Annotated[int, FieldSpec(1)]
    max_transport_latency_c_to_p: Annotated[int, FieldSpec(2)]
    max_transport_latency_p_to_c: Annotated[int, FieldSpec(2)]

    class CisInfo(DataUnit):
        cis_id: Annotated[int, FieldSpec(1)]
        max_sdu_c_to_p: Annotated[int, FieldSpec(2)]
        max_sdu_p_to_c: Annotated[int, FieldSpec(2)]
        phy_c_to_p: Annotated[int, FieldSpec(1)]
        phy_p_to_c: Annotated[int, FieldSpec(1)]
        rtn_c_to_p: Annotated[int, FieldSpec(1)]
        rtn_p_to_c: Annotated[int, FieldSpec(1)]
    
    cis_info: list[CisInfo]

    class Returned(DataUnit):
        status: Annotated[int, STATUS_SPEC]
        cig_id: Annotated[int, FieldSpec(1)]
        connection_handles: Annotated[list[int], FieldSpec(2)]