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Notifier and Listeners

Notifier

The Notifier object is used as a message distributor for a bus. The Notifier uses an event loop or creates a thread to read messages from the bus and distributes them to listeners.

.. autoclass:: can.Notifier
    :members:

Listener

The Listener class is an "abstract" base class for any objects which wish to register to receive notifications of new messages on the bus. A Listener can be used in two ways; the default is to call the Listener with a new message, or by calling the method on_message_received.

Listeners are registered with :ref:`notifier` object(s) which ensure they are notified whenever a new message is received.

.. literalinclude:: ../examples/print_notifier.py
    :language: python
    :linenos:
    :emphasize-lines: 8,9

Subclasses of Listener that do not override on_message_received will cause :class:`NotImplementedError` to be thrown when a message is received on the CAN bus.

.. autoclass:: can.Listener
    :members:

There are some listeners that already ship together with python-can and are listed below. Some of them allow messages to be written to files, and the corresponding file readers are also documented here.

Note

Please note that writing and the reading a message might not always yield a completely unchanged message again, since some properties are not (yet) supported by some file formats.

Note

Additional file formats for both reading/writing log files can be added via a plugin reader/writer. An external package can register a new reader by using the can.io.message_reader entry point. Similarly, a writer can be added using the can.io.message_writer entry point.

The format of the entry point is reader_name=module:classname where classname is a :class:`can.io.generic.BaseIOHandler` concrete implementation.

entry_points={
    'can.io.message_reader': [
       '.asc = my_package.io.asc:ASCReader'
   ]
},

BufferedReader

.. autoclass:: can.BufferedReader
    :members:


.. autoclass:: can.AsyncBufferedReader
    :members:

RedirectReader

.. autoclass:: can.RedirectReader
    :members: