@effect-ts/system/_src/Support/OneShot/index.ts

Effect-TS is a zero dependency set of libraries to write highly productive, purely functional TypeScript at scale.

// ets_tracing: off

import "../../Operator/index.js"

export class OneShot<A> {
  private internal: A | undefined = undefined

  set(a: A) {
    if (this.internal) {
      throw new Error("OneShot already set")
    }
    if (a == null) {
      throw new Error("Cannot set null to OneShot")
    }
    this.internal = a
  }

  get() {
    if (this.internal) {
      return this.internal
    }
    throw new Error("Value not set in OneShot")
  }

  isSet() {
    return this.internal != null
  }
}