Utils

Various decorators for the eix game engine

Getting started

To get started, first install @eix-js/utils with

npm i @eix-js/utils

You also need to include "experimentalDecorators": true in your tsconfig.json.

Singleton

To use the singleton pattern, you can just create a class, and use the @Singleton decorator:

import { Singleton } from "@eix-js/utils"

@Singleton //this class will have only one instance
class TestClass {
    constructor( public prop: number ) { }
}

The instance will be created the frst time you run the constructor:

//instance doesnt exist

const a = new TestClass( 100 ) //instance was created
const b = new TestClass( 200 ) //returns the same instance

console.log(b.prop) // 100
console.log(a == b) //true

Caching

The following decorators are all used to cache results of stuff:

CacheResults

The CacheResults decorator is used to cache the results of methods:

Note: none of these works with default arguments

import { CacheResults } from "@eix-js/utils"

let runCount = 0

class TestClass {
    @CacheResults()
    public foo(bar: number) {
        return Math.random() + bar + runCount++
    }
}

const instance = new TestClass()

// This will always be true, no matter what's inside the function
console.log(instance.foo(1) === instance.foo(1)) // true

// The function only run once
console.log(runCount) // 1

CacheInstances

@CacheInstances()
class TestClass {
    constructor(public foo: string){ }
}

const a = new TestClass('a')
const b = new TestClass('a')
const c = new TestClass('c')

console.log(a === b) // true
console.log(a === c) // false

CacheInstancesByKey

This is a variation of the CacheInstances decorator. It caches instances by saving in a lru cache using a hash as the key. Overall this is more efficient, and should be always used if possible.

Note: This assumes the first argument is a string

@CacheInstancesByKey()
class Foo {
    public constructor(public bar: string) { }
}

const a = new Foo('goo')
const b = new Foo('goo')
const c = new Foo('foo-bar-goo')

console.log(a === b) // true
console.log(b === c) // false

Playing with the source:

Run npm test to run the tests and npm run build to build.