geheugen

geheugen

A memoisation toolkit.

Installation

npm install --save geheugen

Usage

As an ES6 module

import 'promise.prototype.finally';

import { memoise } from 'geheugen';

let memo = memoise({ factory: () => getAsyncValue() });

let promise = memo.resolve()
    .then(asyncValue => { ... })
    
memo.reset();

As an ES5 module

require('babel-polyfill');
require('promise.prototype.finally');

var memoise = require('geheugen').memoise;

var memo = memoise({ factory: function () { return getAsyncValue(); } });

var promise = memo.resolve()
    .then(function (asyncValue) { ... })
    
memo.reset();

In a browser

<script src="babel-polyfill/dist/polyfill.js"></script>
<script src="promise.prototype.finally/finally.js"></script>

<script src="geheugen/dist/geheugen.js"></script>

<script>
    var memo = geheugen.memoise({ factory: function () { return getAsyncValue(); } });

    var promise = memo.resolve()
        .then(function (asyncValue) { ... })
    
    memo.reset();
</script>

API

Memo

constructors

new Memo({ Q, dependencies, factory, promise, value })

Q

Type: Class

Default: Promise

The promise implementation.

The promise implementation should at a minimum implement the following methods:

• Promise.resolve()
• Promise.all()

Note: The promise implementation must implement the .finally() promise method. A polyfill for the ES6 Promise API can be found at https://www.npmjs.com/package/promise.prototype.finally.

dependencies

Type: Array<Memo>

Default: []

The dependencies.

factory

Type: Function

Default: () => {}

The factory.

promise

Type: Promise

The promise.

value

The value.

methods

resolve()

Resolve the memo.

If the memo has a value

Return a promise resolved with the value.

If the memo has a promise

Return the promise.

Otherwise

Invoke the factory and return a promise for the returned value.

The factory will be invoked via .then() of a promise resolved with the values of all of the dependencies.

Whilst the promise is pending it will be stored on the memo. When the promise is fulfilled the stored promise will be removed.

The returned value will be stored on the memo.

reset()

Remove the value from the memo.

Any memo that has specified this memo as a dependency will also be reset.

properties

Q

Type: Class

The promise implementation.

dependencies

Type: Array<Memo>

The dependencies.

factory

Type: Function

The factory.

promise

Type: Promise

The promise.

value

The value.

dependants

Type: Array<Memo>

The dependants.

Any memo that has specified this memo as a dependency will be added to this array.