"""
This Listener simply prints to stdout / the terminal or a file.
"""
import logging
from typing import Optional, TextIO, Union
from ..message import Message
from .generic import MessageWriter
from ..typechecking import StringPathLike
log = logging.getLogger("can.io.printer")
[docs]class Printer(MessageWriter):
"""
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
"""
file: Optional[TextIO]
def __init__(
self, file: Optional[Union[StringPathLike, TextIO]] = None, append: bool = False
) -> 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, is 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
"""
mode = "a" if append else "w"
super().__init__(file, mode=mode)
[docs] def on_message_received(self, msg: Message) -> None:
if self.file is not None:
self.file.write(str(msg) + "\n")
else:
print(msg)