Using Observer Pattern terminology the "signal" comes from the "subject".
By using "getState" the "observer" not only "gets the state" of the subject but also implicitly subscribes to updates to the subject's state. Similarly "setState" triggers the machinery necessary to update anybody who's interested in the updated state.
Using Observer Pattern terminology the "signal" comes from the "subject".
By using "getState" the "observer" not only "gets the state" of the subject but also implicitly subscribes to updates to the subject's state. Similarly "setState" triggers the machinery necessary to update anybody who's interested in the updated state.
See Finding Fine-Grained Reactive Programming: How It Works