Effect Handler

Overview

Effect Handlers execute Effect messages and potentially produce Events as a result.

A Mobius loop has a single Effect Handler, which is usually composed of individual Effect Handlers for Effect type. (See Modules > Coroutines for how to compose Coroutine-based Effect Handlers.)

Model data should be passed to the Effect handler within the Effect object. An Effect Handler could subscribe to Model updates at the cost of races and reduce simplicity.

Exceptions

Effect Handlers can never throw Exceptions, it will cause a crash or put the loop in an unusable state. If an error occurs while executing an Effect, it should be transformed into an Event to be processed by the Update function.

Connections

Effect Handlers are connected to a MobiusLoop with a Connection, this allows the loop to send Effects to the handler and signal when shut down is required.

Effect Handlers that can only be connected to once, which is generally the case, must throw the ConnectionLimitExceeded exception to prevent difficult to identify bugs. If an Effect Handler instance can be shared with multiple loops, ensure that it is prepared to handle it.