A memoisation toolkit
npm install @kjots/geheugen
> A memoisation toolkit.
``shell`
npm install --save @kjots/geheugen
`js
import 'promise.prototype.finally';
import { memoise } from '@kjots/geheugen';
let memo = memoise({ factory: () => getAsyncValue() });
let promise = memo.resolve()
.then(asyncValue => { ... })
memo.reset();
`
`js
require('babel-polyfill');
require('promise.prototype.finally');
var memoise = require('@kjots/geheugen').memoise;
var memo = memoise({ factory: function () { return getAsyncValue(); } });
var promise = memo.resolve()
.then(function (asyncValue) { ... })
memo.reset();
`
`html
`
#### constructors
##### new Memo({ Q, singleton, dependencies, onSet, onReset factory, promise, value })
###### Q
Type: Class
Default: Promise
The promise implementation.
The promise implementation should at a minimum implement the following methods:
* Promise.resolve()
*
Note: The promise implementation must implement the promise method. A polyfill for the ES6 Promise
API can be found at https://www.npmjs.com/package/promise.prototype.finally.
###### singleton
Type: Boolean
Default: true
The singleton flag.
###### dependencies
Type: Array
Default: []
The dependencies.
###### onSet
Type: Function
Default: (value) => {}
The set event handler.
The set event handler will be invoked when the set() method is invoked.
###### onReset
Type: Function
Default: () => {}
The reset event handler.
The reset event handler will be invoked when the reset() method is invoked.
###### 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 and the singleton flag is set
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.
##### get()
Return the value the the memo.
##### set()
Update the value of the memo.
The set event handler will be invoked before the value is updated. If the set event handler throws an error the set
operation will be aborted.
Any memo that has specified this memo as a dependency will be reset.
##### reset()
Remove the value from the memo.
The reset event handler will be invoked before the value is removed. If the reset event handler throws an error the
reset operation will be aborted.
Any memo that has specified this memo as a dependency will also be reset.
##### resetDependants()
Reset all memos that have specified this memo as a dependency.
#### properties
##### Q
Type: Class
The promise implementation.
##### singleton
Type: Boolean
The singleton flag.
##### dependencies
Type: Array
The dependencies.
###### onSet
Type: Function
The set event handler.
###### onReset
Type: Function
The reset event handler.
##### factory
Type: Function
The factory.
##### promise
Type: Promise
The promise.
##### value
The value.
##### dependants
Type: Array
The dependants.
Any memo that has specified this memo as a dependency will be added to this array.