Redux dependency injection reducers

Rationale

A function combineDiReducers() handles depedency injection into reducers in tree.

Usage

combineDiReducers() accepts reducer tree:

const reducerTree = {
  foo: makePlainReducer('initial foo', (state, action) => (
    action.type === 'UPDATE_ACTION' ? 'foo updated' : state
  )),
  bar: makeDiReducer(
    'initial foo',
    {foo: '@foo', fox: '@baz.fox'},
    (state, action, {foo, fox}, changes: ExReducerDependenciesChanges) => {
        if (changes.for('foo')) return foo;
        else if (changes.for('fox')) return fox;
        return state;
    }
  ),
  baz: {
    fox: makeDiReducer(
        'initial state',
        {foo: '@foo'},
        (state, action, {foo}, changes: ExReducerDependenciesChanges) => {
            return changes.yes() ? foo : state;
        }
    )
  }
};
const rootReducer = combineDiReducers(reducerTree);

• makePlainReducer(): returns reducer which handles initial state
• makeDiReducer: returns reducer which handles initial state and has dependency specification stored
• combineDiReducers(): returns a root reducer, which will traverse reducers tree and handle depedency injection.

Key features:

• all depedencies are resolved in one cycle for one action
• dependency paths formats:
  • @some.path: absolute path from any place in tree to root state
  • ^sibling.path: path to sibling branch
  • ^^parentSibling.path: path to parent's sibling branch
• dependent ex reducers and plain reducers can be mixed in any order

Limitations:

• no cycle depedencies
• no dependencies to 'ancestors'

Development

• update version: npm version
• publish: npm publish