Manual Bitwise Parsing and Lack of Strong Schemas

[RaulSMS]

The library depends heavily on manual bit shifts (<<, >>) and bitwise masking (&, |) applied directly inside operational code to parse the 29-bit J1939 identifier (Priority, Data Page, PDU Format, PDU Specific, Source Address) and the 64-bit ECU NAME field.

• This creates a highly imperative codebase that is prone to off-by-one errors and makes onboarding or debugging incredibly tedious.
• Data integrity relies entirely on runtime type handling without leveraging static type validation capabilities.

Proposed Architecture Fix

Utilize Python 3.10's modern, optimized @dataclass(slots=True) syntax to create immutable, strongly typed schemas for J1939 data primitives.

• The use of slots=True minimizes memory overhead and optimizes attribute lookup performance for low-level message routing.
• Integrate Python 3.10's Structural Pattern Matching (match/case) to cleanly route packets based on PDU format combinations.

Architectural Example (Python 3.10):

from dataclasses import dataclass

@dataclass(frozen=True, slots=True)
class J1939Identifier:
    priority: int
    pgn: int
    source_address: int
    destination_address: int | None = None

# High-performance, declarative dispatching
def dispatch_pdu(pdu_format: int, pdu_specific: int, frame_data: bytes):
    match (pdu_format, pdu_specific):
        case (236, _):
            # Route to Transport Connection Management Handler
            process_tp_cm(frame_data)
        case (235, _):
            # Route to Transport Data Transfer Handler
            process_tp_dt(frame_data)
        case (pdu_f, _) if pdu_f >= 240:
            # Global broadcast PGN pattern
            process_broadcast_pgn(pdu_format, pdu_specific, frame_data)
        case _:
            process_peer_to_peer(pdu_format, pdu_specific, frame_data)

Caution

This issue needs clarification since it may be a large rework and benefits is not that clear yet.