wellcrafted/dist/function.d.ts

Delightful TypeScript patterns for elegant, type-safe applications

//#region src/function.d.ts
/**
 * Run-at-most-once wrapper. Wrap `fn` so the first call invokes it and caches the result;
 * every later call is a no-op that returns that same cached result. Arguments passed after
 * the first call are ignored.
 *
 * Canonical use: an idempotent `[Symbol.dispose]` whose teardown is reachable from more than
 * one path and must not run twice. `once` makes that guarantee declarative instead of a
 * hand-rolled `let disposed` flag.
 *
 * This is for the pure "this function body runs at most once" case. A boolean that is ALSO
 * read by other methods to short-circuit a dead object is a liveness flag, not a once-guard;
 * keep that boolean, `once` does not replace it.
 *
 * @example
 * ```ts
 * import { once } from "wellcrafted/function";
 *
 * const init = once(() => expensiveSetup());
 * init(); // runs expensiveSetup()
 * init(); // returns the cached result, does not run again
 * ```
 *
 * @example Idempotent disposal
 * ```ts
 * import { once } from "wellcrafted/function";
 *
 * const dispose = once(() => closeConnection());
 * // safe to call from multiple teardown paths; closeConnection() runs at most once
 * ```
 */
declare function once<TArgs extends readonly unknown[], TReturn>(fn: (...args: TArgs) => TReturn): (...args: TArgs) => TReturn;
//# sourceMappingURL=function.d.ts.map
//#endregion
export { once };
//# sourceMappingURL=function.d.ts.map