README.md

ember-cached-decorator-polyfill

Polyfill for RFC 566 "@cached decorator".

Installation

ember install ember-cached-decorator-polyfill

For addons, pass the -S flag.

If you're working in an environment with an explicit Babel config (like a V2 addon or an app with ember-cli-babel's { useBabelConfig: true } mode), see "Explicit Babel Config" below.

Compatibility

• Ember.js v3.13 or above
• Ember CLI v2.13 or above
• Node.js v14 or above

Summary

Add a @cached decorator for memoizing the result of a getter based on autotracking. In the following example, fullName would only recalculate if firstName or lastName is updated.

import { tracked, cached } from '@glimmer/tracking';

class Person {
  @tracked firstName = 'Jen';
  @tracked lastName = 'Weber';

  @cached
  get fullName() {
    return `${this.firstName} ${this.lastName}`;
  }
}

For detailed usage instructions, refer to the RFC 566 "@cached decorator".

TypeScript Usage

TypeScript's normal type resolution for an import from @glimmer/tracking will not find the types provided by this polyfill, since the actual @glimmer/tracking package does not include an export for cache.

In order for TypeScript to recognize the extra cache export, add an import like this somewhere in your codebase (like app.ts or test-helper.ts):

import 'ember-cached-decorator-polyfill';

Once the upstream types have been updated to reflect RFC 566, this will no longer be necessary.

Explicit Babel Config

In environments where you have an explicit Babel config (like authoring a V2 addon) you will need to configure this polyfill's babel plugin. Add it to your babel.config.js like:

{
  "plugins": [
    "ember-cached-decorator-polyfill/babel-plugin"
  ]
}