Abstract: The present disclosure relates to medicament injection devices. An injection device includes: a movable dosage programming component comprising a rotary encoder system having a predefined angular periodicity, a sensor arrangement including a first optical sensor configured to detect movement of the movable dosage programming component relative to the sensor arrangement during dosing of a medicament, wherein the first optical sensor is configured to operate in a strobe-sampling mode at a first frequency, a second optical sensor configured to detect movement of the rotary encoder system relative to the second optical sensor wherein the second optical sensor is configured to operate in a strobe-sampling mode at a second frequency lower than the first frequency, and a processor arrangement configured to, based on the detected movement, determine a medicament dosage administered by the injection device.

Abstract: Embodiments are directed to dynamically determining event listeners. A computer system sends a query to a data store to determine which event listeners are configured to listen for an indicated event. The event listeners are registered in the data store without the software module having to explicitly declare its event listeners. The computer system receives from the data store an indication of those event listeners that are configured to listen for the event. The computer system also sends the event to those event listeners indicated by the data store as being registered to receive notification of the event's occurrence.