cycle-gear

cycle-gear

cycle-gear is a formalization of the CycleJS MVI pattern and a main function factory (pedal) to make use of the pattern.

Why Formalize?

Cycle's documentation on the CycleJS MVI pattern makes it clear that Cycle's goal is not to formalize the MVI pattern into the framework.

Formalizing an architecture pattern, however, can provide a common component platform and organization scheme to a project. cycle-gear is one approach to componentizing the pieces of a CycleJS main component into a form encouraging separation of concerns, and easy reuse of the component parts.

The Pattern

A Gear consists of an intent, model, and a set of teeth comprising of a filter and a view.

The intent responds to the changes from the gear's sources, converting them into actions for a model to respond to.

The model takes the actions of the gear's intent and produces a single observable of model states.

A tooth produces output to a gear's sinks by filtering the gear's model states and presenting them through a view.

The catch will handle the gear's model errors. While this could be manually done for each gear model, as a top level part of a gear it encourages the ability to handle errors systematically, such as how each tooth might deal with it. (It also allows for a catch to be defaulted across a transmission, helping avoid issues with a "stuck" transmission.)

pedal

pedal is a main factory function for the Gear pattern. It takes a transmission of Gears, default states for gears, which teeth to bind to which sinks, and from that builds a Cycle main to wire the gears up to Cycle sources and sinks.

A transmission is an observable of gears or a factory from Cycle sources to an observable of gears. At the top level of an application might be a transmission defined by a history router such as @cycle/history, and at lower levels a transmission might be some other sort of user-action dependent state machine.