feat!: change the options type of defineWorkerFns()

Also add function type support for DefineWorkerFnOpts.transfer

src/define.ts

@@ -15,10 +15,10 @@ const _global = Function("return this")() as MsgPortNormalized;
  * @param fn - The worker function.
  * @param options - An object containing options.
  */
-export function defineWorkerFn(
+export function defineWorkerFn<FN extends AnyFn>(
   name: string,
-  fn: AnyFn,
-  options: DefineWorkerFnOpts = {},
+  fn: FN,
+  options: DefineWorkerFnOpts<FN> = {},
 ): void {
   const { transfer, port = _global } = options;
   const rpcAgent = RpcAgent.getRpcAgent(port);
@@ -37,12 +37,14 @@ export function defineWorkerFn(
  * @param functions - An object containing worker functions. Keys will be used as the names of the worker functions.
  * @param options - An object containing options.
  */
-export function defineWorkerFns(
-  functions: Record<string, AnyFn>,
-  options: DefineWorkerFnOpts = {},
+export function defineWorkerFns<FNS extends Record<string, AnyFn>>(
+  functions: FNS,
+  options: {
+    [NAME in keyof FNS]?: DefineWorkerFnOpts<FNS[NAME]>;
+  } = {},
 ): void {
   for (const [name, fn] of Object.entries(functions)) {
-    defineWorkerFn(name, fn, options);
+    defineWorkerFn(name, fn, options[name]);
   }
 }
 

src/rpc/rpc.ts

@@ -31,7 +31,7 @@ export class RpcAgent {
     string,
     Map<string, {
       fn: AnyFn;
-      transfer: boolean;
+      transfer: boolean | ((ctx: { ret: any }) => Transferable[]);
     }>
   >();
 
@@ -62,9 +62,9 @@ export class RpcAgent {
     this.#startListening();
   }
 
-  defineLocalFn(name: string, fn: AnyFn, options: {
+  defineLocalFn<FN extends AnyFn>(name: string, fn: FN, options: {
     namespace?: string;
-    transfer?: boolean;
+    transfer?: boolean | ((ctx: { ret: ReturnType<FN> }) => Transferable[]);
   } = {}) {
     const { namespace = DEFAULT_NAMESPACE, transfer = true } = options;
 
@@ -83,7 +83,7 @@ export class RpcAgent {
     namespace?: string;
     transfer?: boolean | ((ctx: { args: Parameters<FN> }) => Transferable[]);
   } = {}) {
-    const { namespace = DEFAULT_NAMESPACE, transfer } = options;
+    const { namespace = DEFAULT_NAMESPACE, transfer = true } = options;
 
     const keyCallMap = this.#getKeyCallMap(namespace, true);
 
@@ -195,7 +195,9 @@ export class RpcAgent {
             // transferables exist due to them not being able to be cloned, so to ensure in a complex object we grab all the
             // transferables that can't be cloned we traverse the entire object finding all transferables, and listing them to be transferred
             transfer: transfer
-              ? getTransferables(ret, supportFlags.streams)
+              ? transfer === true
+                ? getTransferables(ret, supportFlags.streams)
+                : transfer?.({ ret })
               : undefined,
           });
         } catch (err) {

src/types.ts

@@ -22,14 +22,15 @@ export type InternalFns = {
 
 /* -------------------------------------------------- options -------------------------------------------------- */
 
-export interface DefineWorkerFnOpts {
+export interface DefineWorkerFnOpts<FN extends AnyFn> {
   /**
-   * Whether to transfer the transferable objects exist in the return value of the worker function.
+   * A boolean value indicating whether to transfer the transferable objects exist in the return value of the worker function,
+   * or a function that returns transferable objects should be transferred.
    *
    * @default true
    * @see https://developer.mozilla.org/en-US/docs/Web/API/Worker/postMessage#transfer
    */
-  transfer?: boolean;
+  transfer?: boolean | ((ctx: { ret: ReturnType<FN> }) => Transferable[]);
 
   /**
    * The message port to communicate with the main thread.
@@ -45,10 +46,11 @@ export interface DefineWorkerFnOpts {
 
 export interface UseWorkerFnOpts<FN extends AnyFn> {
   /**
-   * A boolean value indicating whether to transfer the transferable objects exist in the arguments, or a function that returns transferable objects should be transferred.
+   * A boolean value indicating whether to transfer the transferable objects exist in the arguments,
+   * or a function that returns transferable objects should be transferred.
    *
+   * @default true
    * @see https://developer.mozilla.org/en-US/docs/Web/API/Worker/postMessage#transfer
-   * @returns Transferable objects.
    */
   transfer?: boolean | ((ctx: { args: Parameters<FN> }) => Transferable[]);
 }

test/fns.test.worker.ts

@@ -9,6 +9,8 @@ const fns = {
   },
 };
 
-defineWorkerFns(fns);
+defineWorkerFns(fns, {
+  fib: { transfer: false },
+});
 
 export type Fns = typeof fns;