If this signal is computed from sources that change their value via a side effect (such as signals) and is not informed of those changes while unwired (e.g.
If this signal is computed from sources that change their value via a side effect (such as signals) and is not informed of those changes while unwired (e.g. because this signal removes itself from the sources' children lists in #onUnwire), it is mandatory to update/recompute this signal's value from the sources in #onWire, since a dispatch always happens after #onWire. This is true even if the source values themselves did not change, for the recomputation in itself may rely on side effects (e.g. ZMessaging => SomeValueFromTheDatabase).
This also implies that a signal should never #dispatch in #onWire because that will happen anyway immediately afterwards in #subscribe.
A cold signal that loads some initial data whenever the first listener subscribes to it and then - while there are subscribers - listens to updates from a publisher, updating the current data using the received events and the provided update function.