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Asyncio advanced topics
+++++++++++++++++++++++++
.. py:currentmodule:: sdbus
Signals without data
^^^^^^^^^^^^^^^^^^^^
D-Bus allows signals to not carry any data. Such signals have the
type signature of ``""``. (empty string)
To emit such signals the :py:meth:`emit <DbusSignalAsync.emit>` must
be explicitly called with ``None``.
Example of an empty signal::
from asyncio import new_event_loop
from sdbus import DbusInterfaceCommonAsync, dbus_signal_async
class ExampleInterface(
DbusInterfaceCommonAsync,
interface_name="org.example.signal"
):
@dbus_signal_async("")
def name_invalidated(self) -> None:
raise NotImplementedError
test_object = ExampleInterface()
async def emit_empty_signal() -> None:
test_object.export_to_dbus("/")
test_object.name_invalidated.emit(None)
loop = new_event_loop()
loop.run_until_complete(emit_empty_signal())
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