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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 | 2x 2x 1x 1x 8x 1x 8x 1x 1x | import { copyStaticProperties } from './Helper';
/**
* Singleton decorator.
* @param constructor The constructor to create a singleton from.
* @param args Other arguments from the decorator interface.
* @returns The singleton class.
* @remarks - To get the singleton instance, call the constructor.
* - Place this decorator directly above the class declaration
* @example
* ```ts
* \@anotherDecorators //---> third priority
* \@otherDecorators //--> second priority
* \@Singleton //-> first priority
* class MyClass { // Place the Singleton decorator
* constructor() { // directly above the class declaration
* // ... // for priority above other decorators!
* }
* }
*
* const instance = new MyClass();
* const instance2 = new MyClass();
*
* console.log(instance === instance2); // true
* ```
*/
export function Singleton<
TargetType extends new (...args: unknown[]) => InstanceType<TargetType>,
>(constructor: TargetType, ...args: unknown[]): TargetType {
const original = constructor;
let instance: InstanceType<TargetType>;
/**
* Wraps the constructor to create a singleton.
* @param args The arguments for the constructor.
* @returns The singleton instance.
*/
const wrappedConstructor = function (
...args: unknown[]
): InstanceType<TargetType> {
if (!instance) {
instance = new constructor(...args) as InstanceType<TargetType>;
}
return instance;
};
// Transfer prototype
wrappedConstructor.prototype = constructor.prototype;
// Copy static methods and properties
return copyStaticProperties(wrappedConstructor, original);
}
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