Improve can.io.* type hierarchy and annotations

.github/workflows/ci.yml

@@ -76,7 +76,7 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v5
       with:
-        python-version: "3.10"
+        python-version: "3.13"
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip

can/_entry_points.py

@@ -30,5 +30,5 @@ def read_entry_points(group: str) -> list[_EntryPoint]:
     def read_entry_points(group: str) -> list[_EntryPoint]:
         return [
             _EntryPoint(ep.name, *ep.value.split(":", maxsplit=1))
-            for ep in entry_points().get(group, [])
+            for ep in entry_points().get(group, [])  # pylint: disable=no-member
         ]

can/io/asc.py

@@ -39,8 +39,6 @@ class ASCReader(TextIOMessageReader):
     bus statistics, J1939 Transport Protocol messages) is ignored.
     """
 
-    file: TextIO
-
     def __init__(
         self,
         file: Union[StringPathLike, TextIO],
@@ -322,8 +320,6 @@ class ASCWriter(TextIOMessageWriter):
     It the first message does not have a timestamp, it is set to zero.
     """
 
-    file: TextIO
-
     FORMAT_MESSAGE = "{channel}  {id:<15} {dir:<4} {dtype} {data}"
     FORMAT_MESSAGE_FD = " ".join(
         [

can/io/blf.py

@@ -17,14 +17,14 @@
 import struct
 import time
 import zlib
-from collections.abc import Generator
+from collections.abc import Generator, Iterator
 from decimal import Decimal
 from typing import Any, BinaryIO, Optional, Union, cast
 
 from ..message import Message
 from ..typechecking import StringPathLike
 from ..util import channel2int, dlc2len, len2dlc
-from .generic import BinaryIOMessageReader, FileIOMessageWriter
+from .generic import BinaryIOMessageReader, BinaryIOMessageWriter
 
 TSystemTime = tuple[int, int, int, int, int, int, int, int]
 
@@ -104,7 +104,7 @@ class BLFParseError(Exception):
 TIME_ONE_NANS_FACTOR = Decimal("1e-9")
 
 
-def timestamp_to_systemtime(timestamp: float) -> TSystemTime:
+def timestamp_to_systemtime(timestamp: Optional[float]) -> TSystemTime:
     if timestamp is None or timestamp < 631152000:
         # Probably not a Unix timestamp
         return 0, 0, 0, 0, 0, 0, 0, 0
@@ -146,8 +146,6 @@ class BLFReader(BinaryIOMessageReader):
     silently ignored.
     """
 
-    file: BinaryIO
-
     def __init__(
         self,
         file: Union[StringPathLike, BinaryIO],
@@ -206,7 +204,7 @@ def __iter__(self) -> Generator[Message, None, None]:
                 yield from self._parse_container(data)
         self.stop()
 
-    def _parse_container(self, data):
+    def _parse_container(self, data: bytes) -> Iterator[Message]:
         if self._tail:
             data = b"".join((self._tail, data))
         try:
@@ -217,7 +215,7 @@ def _parse_container(self, data):
         # Save the remaining data that could not be processed
         self._tail = data[self._pos :]
 
-    def _parse_data(self, data):
+    def _parse_data(self, data: bytes) -> Iterator[Message]:
         """Optimized inner loop by making local copies of global variables
         and class members and hardcoding some values."""
         unpack_obj_header_base = OBJ_HEADER_BASE_STRUCT.unpack_from
@@ -375,13 +373,11 @@ def _parse_data(self, data):
             pos = next_pos
 
 
-class BLFWriter(FileIOMessageWriter):
+class BLFWriter(BinaryIOMessageWriter):
     """
     Logs CAN data to a Binary Logging File compatible with Vector's tools.
     """
 
-    file: BinaryIO
-
     #: Max log container size of uncompressed data
     max_container_size = 128 * 1024
 
@@ -412,14 +408,12 @@ def __init__(
             Z_DEFAULT_COMPRESSION represents a default compromise between
             speed and compression (currently equivalent to level 6).
         """
-        mode = "rb+" if append else "wb"
         try:
-            super().__init__(file, mode=mode)
+            super().__init__(file, mode="rb+" if append else "wb")
         except FileNotFoundError:
             # Trying to append to a non-existing file, create a new one
             append = False
-            mode = "wb"
-            super().__init__(file, mode=mode)
+            super().__init__(file, mode="wb")
         assert self.file is not None
         self.channel = channel
         self.compression_level = compression_level
@@ -452,7 +446,7 @@ def __init__(
             # Write a default header which will be updated when stopped
             self._write_header(FILE_HEADER_SIZE)
 
-    def _write_header(self, filesize):
+    def _write_header(self, filesize: int) -> None:
         header = [b"LOGG", FILE_HEADER_SIZE, self.application_id, 0, 0, 0, 2, 6, 8, 1]
         # The meaning of "count of objects read" is unknown
         header.extend([filesize, self.uncompressed_size, self.object_count, 0])
@@ -462,7 +456,7 @@ def _write_header(self, filesize):
         # Pad to header size
         self.file.write(b"\x00" * (FILE_HEADER_SIZE - FILE_HEADER_STRUCT.size))
 
-    def on_message_received(self, msg):
+    def on_message_received(self, msg: Message) -> None:
         channel = channel2int(msg.channel)
         if channel is None:
             channel = self.channel
@@ -514,7 +508,7 @@ def on_message_received(self, msg):
             data = CAN_MSG_STRUCT.pack(channel, flags, msg.dlc, arb_id, can_data)
             self._add_object(CAN_MESSAGE, data, msg.timestamp)
 
-    def log_event(self, text, timestamp=None):
+    def log_event(self, text: str, timestamp: Optional[float] = None) -> None:
         """Add an arbitrary message to the log file as a global marker.
 
         :param str text:
@@ -525,17 +519,19 @@ def log_event(self, text, timestamp=None):
         """
         try:
             # Only works on Windows
-            text = text.encode("mbcs")
+            encoded = text.encode("mbcs")
         except LookupError:
-            text = text.encode("ascii")
+            encoded = text.encode("ascii")
         comment = b"Added by python-can"
         marker = b"python-can"
         data = GLOBAL_MARKER_STRUCT.pack(
-            0, 0xFFFFFF, 0xFF3300, 0, len(text), len(marker), len(comment)
+            0, 0xFFFFFF, 0xFF3300, 0, len(encoded), len(marker), len(comment)
         )
-        self._add_object(GLOBAL_MARKER, data + text + marker + comment, timestamp)
+        self._add_object(GLOBAL_MARKER, data + encoded + marker + comment, timestamp)
 
-    def _add_object(self, obj_type, data, timestamp=None):
+    def _add_object(
+        self, obj_type: int, data: bytes, timestamp: Optional[float] = None
+    ) -> None:
         if timestamp is None:
             timestamp = self.stop_timestamp or time.time()
         if self.start_timestamp is None:
@@ -564,7 +560,7 @@ def _add_object(self, obj_type, data, timestamp=None):
         if self._buffer_size >= self.max_container_size:
             self._flush()
 
-    def _flush(self):
+    def _flush(self) -> None:
         """Compresses and writes data in the buffer to file."""
         if self.file.closed:
             return
@@ -578,7 +574,7 @@ def _flush(self):
         self._buffer = [tail]
         self._buffer_size = len(tail)
         if not self.compression_level:
-            data = uncompressed_data
+            data: "Union[bytes, memoryview[int]]" = uncompressed_data  # noqa: UP037
             method = NO_COMPRESSION
         else:
             data = zlib.compress(uncompressed_data, self.compression_level)
@@ -601,7 +597,7 @@ def file_size(self) -> int:
         """Return an estimate of the current file size in bytes."""
         return self.file.tell() + self._buffer_size
 
-    def stop(self):
+    def stop(self) -> None:
         """Stops logging and closes the file."""
         self._flush()
         if self.file.seekable():

can/io/canutils.py

@@ -6,7 +6,7 @@
 
 import logging
 from collections.abc import Generator
-from typing import Any, TextIO, Union
+from typing import Any, Optional, TextIO, Union
 
 from can.message import Message
 
@@ -34,8 +34,6 @@ class CanutilsLogReader(TextIOMessageReader):
         ``(0.0) vcan0 001#8d00100100820100``
     """
 
-    file: TextIO
-
     def __init__(
         self,
         file: Union[StringPathLike, TextIO],
@@ -148,13 +146,12 @@ def __init__(
         :param bool append: if set to `True` messages are appended to
                             the file, else the file is truncated
         """
-        mode = "a" if append else "w"
-        super().__init__(file, mode=mode)
+        super().__init__(file, mode="a" if append else "w")
 
         self.channel = channel
-        self.last_timestamp = None
+        self.last_timestamp: Optional[float] = None
 
-    def on_message_received(self, msg):
+    def on_message_received(self, msg: Message) -> None:
         # this is the case for the very first message:
         if self.last_timestamp is None:
             self.last_timestamp = msg.timestamp or 0.0

can/io/csv.py

@@ -28,8 +28,6 @@ class CSVReader(TextIOMessageReader):
     Any line separator is accepted.
     """
 
-    file: TextIO
-
     def __init__(
         self,
         file: Union[StringPathLike, TextIO],
@@ -89,8 +87,6 @@ class CSVWriter(TextIOMessageWriter):
     Each line is terminated with a platform specific line separator.
     """
 
-    file: TextIO
-
     def __init__(
         self,
         file: Union[StringPathLike, TextIO],
@@ -106,8 +102,7 @@ def __init__(
                             the file is truncated and starts with a newly
                             written header line
         """
-        mode = "a" if append else "w"
-        super().__init__(file, mode=mode)
+        super().__init__(file, mode="a" if append else "w")
 
         # Write a header row
         if not append: