signaling
is a simple implementation of the signal/slot pattern as
known from the Qt framework.
It has no external requirements and 100% test-coverage.
The usual
pip install signaling
Consider that you have a function that should be called whenever a connected signal is emitted, as illustrated by the following code block:
def slot(arg):
print("Slot called with {}".format(arg))
signal = Signal(args=['arg'])
signal.connect(slot)
signal.emit(arg=1) # Slot called with 1
In fact you can connect multiple slots to the same signal, as long as they share the same function signature.
Notice that the signaling
library performs some sanity checks when connecting
slots and emitting signals.
- All slots connected to a signal have to provide the same argument specifiction as
denoted by the
args
parameter of theSignal
constructor. - An
emit
-call has to be made with the exact same arguments as specified with theSignal
constructor.
So all of the below examples would raise an exception:
def slot_with_arg(arg):
pass
def slot_without_arg():
pass
# InvalidSlot: Slot 'slot_with_arg' has to callable without arguments
Signal().connect(slot_with_arg)
# InvalidSlot: Slot 'slot_without_args' has to accept args ['arg'] or **kwargs.
Signal(args['arg']).connect(slot_without_arg)
s = Signal()
s.connect(slot_without_args)
# InvalidEmit: Emit has to be called without arguments.
s.emit(foo=1)