- singleton
- Installation
- Quick start
- Usage without decorators
- Inheritance
- In depth

singleton

Singleton. No constructor monkeypatching. Zero dependencies. Built with TypeScript.

Installation

1. Run
``sh
npm i @keenondrums/singleton
`
1. (Optional) Enable decorators

1. If you use TypeScript set in you tsconfig.json

`json
{
"compilerOptions": {
"experimentalDecorators": true
}
}
`

1. If you use JavaScript configure your babel to support decorators and class properties

Quick start

`ts
import { singleton } from '@keenondrums/singleton'

@singleton
class Test {}

new Test() === new Test() // returns true
`

Usage without decorators

`ts
import { singleton } from '@keenondrums/singleton'

class Test {}
const TestSingleton = singleton(Test)

new TestSingleton() === new TestSingleton() // returns true
`

Inheritance

Any child of your singleton will not be a singleton.

`ts
import { singleton } from '@keenondrums/singleton'

@singleton
class Parent {}

class Child extends Parent {}

new Child() === new Child() // returns false

// If you want to make Child a singleton as well, apply singleton decorator directly to it
@singleton
class ChildSingleton extends Parent {}

new ChildSingleton() === new ChildSingleton() // returns true
`

In depth

singleton decorator wraps your class with a Proxy and a construct trap to override class' creation logic.

Your singleton instance is always available as a static property of a class by key SINGLETON_KEY.

`ts
import { singleton, SINGLETON_KEY } from '@keenondrums/singleton'

@singleton
class Test {}

const instance = new Test()
Test[SINGLETON_KEY] === instance // returns true
``