EP 003 - Enabling Creation Of Reusable Components

Status: Placeholder. Don't bother reading yet.

Abstract

This EP proposes changes to facilitate easier use of React's Context feature. XXX to make it easier to write more complex Reusable components.

Background

React components form a tree, with values being passed down through the hierarchy in the form of props. All very functional.

Except there are some problems:

• it can be a PITA to pass every little bit of data through many, many layers. Manual and time consuming.
• often we don't want to burden intermediate layers with knowledge about what leaf nodes needed. That kind of "unnecessary knowing" leads to various kinds of fragility.
• if we are using someone else's layout components, we may have not have control over what they pass to children.

Algebraic Effects are intended to help solve these kinds of problems in a functional way, but that's not our world.

The solution available in React is called Context. It is a mechanism for allowing
data to be "shared" globally within a given tree of React components (without it needing for it to be passed/threaded through all layers of that tree).

React's context docs are here.

Components

re-com is a library which supplies reusable Reagent widgets. And widgets, like a datepicker, are the simplest kind of components.

re-com components are reusability because they take an input stream of data and they

achieves reusablity by passing in values and suppling callbacks. This works at the level of simple widgets.

But re-frame components need to subscribe and dispatch.

XXX talk about dispatch back rather than callback

XXX need to identify the part of app-db on which event handlers and subscriptions should operate.