Getter recalculation/caching?

[rattrayalex]

The docs don't mention whether Getters are recalculated every time, or just once between Store updates. It seems this implementation should allow at least per-update caching/memoization. Is that implemented/on the roadmap? Could this be mentioned in the docs?

[jordangarcia]

In 0.5.x getter evaluation is pretty naive with no caching. In 0.6.0 which should be released soon (Optimizely is currently using the next branch and I would suggest you do as well) there is very efficient caching / memoization.

Here is an overview

Getters are only calculated whenever their dependencies change. So if the dependency is a keypath then it will only recalculate when that path in the app state map has changed (which can be done as a simple state.getIn(keyPath) !== oldState.getIn(keyPath) which is an O(log32(n)) operation. The other case is when a getter is dependent on other getters. Since every getter is a pure function then Nuclear will only recompute the getter if the values of its dependencies change.

You can read more of the implementation here:

https://github.com/optimizely/nuclear-js/blob/next-update-readme-example/src/evaluator.js

[rattrayalex]

I'm salivating. Thanks!!

[rattrayalex]

This issue should be closable now, though it would probably be good to have this documented in the Readme; all there is on this now is

By making the transform functions pure, you can test Getters easier, compose them easier, and nuclear can memoize calls to them, making Getter dependency resolution very performant.

[jordangarcia]

Closed in #40