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"""
This Listener simply prints to stdout / the terminal or a file.
"""
import logging
import sys
from io import TextIOWrapper
from typing import Any, TextIO, Union
from ..message import Message
from ..typechecking import StringPathLike
from .generic import TextIOMessageWriter
log = logging.getLogger("can.io.printer")
class Printer(TextIOMessageWriter):
"""
The Printer class is a subclass of :class:`~can.Listener` which simply prints
any messages it receives to the terminal (stdout). A message is turned into a
string using :meth:`~can.Message.__str__`.
:attr write_to_file: `True` if this instance prints to a file instead of
standard out
"""
def __init__(
self,
file: Union[StringPathLike, TextIO, TextIOWrapper] = sys.stdout,
append: bool = False,
**kwargs: Any,
) -> None:
"""
:param file: An optional path-like object or a file-like object to "print"
to instead of writing to standard out (stdout).
If this is a file-like object, it has to be opened in text
write mode, not binary write mode.
:param append: If set to `True` messages, are appended to the file,
else the file is truncated
"""
super().__init__(file, mode="a" if append else "w")
def on_message_received(self, msg: Message) -> None:
self.file.write(str(msg) + "\n")
def file_size(self) -> int:
"""Return an estimate of the current file size in bytes."""
if self.file is not sys.stdout:
return self.file.tell()
return 0
def stop(self) -> None:
if self.file is not sys.stdout:
super().stop()
|
