feat(core): factory bind accept function for default value

Author: josepot

packages/core/src/bind/connectFactoryObservable.test.tsx

@@ -541,6 +541,33 @@ describe("connectFactoryObservable", () => {
       unmount()
     })
 
+    it("the defaultValue can be a function that receives the keys", () => {
+      const subj$ = new Subject<number>()
+      const [useNumber, number$] = bind(
+        (_: number) => subj$,
+        (key) => key,
+      )
+
+      const { result, unmount } = renderHook(() => useNumber(10))
+
+      expect(result.current).toBe(10)
+      let res = 0
+      number$(10)
+        .subscribe((x) => {
+          res = x
+        })
+        .unsubscribe()
+      expect(res).toBe(10)
+
+      actHook(() => {
+        subj$.next(5)
+      })
+
+      expect(result.current).toBe(5)
+
+      unmount()
+    })
+
     it("if the observable hasn't emitted and a defaultValue is provided, it does not start suspense", () => {
       const number$ = new Subject<number>()
       const [useNumber] = bind(

packages/core/src/bind/connectFactoryObservable.ts

@@ -25,12 +25,15 @@ import { SUSPENSE } from "../SUSPENSE"
  */
 export default function connectFactoryObservable<A extends [], O>(
   getObservable: (...args: A) => Observable<O>,
-  defaultValue: O,
+  defaultValue: O | ((...args: A) => O),
 ): [
   (...args: A) => Exclude<O, typeof SUSPENSE>,
   (...args: A) => Observable<O>,
 ] {
   const cache = new NestedMap<A, BehaviorObservable<O>>()
+  const getDefaultValue = (typeof defaultValue === "function"
+    ? defaultValue
+    : () => defaultValue) as (...args: A) => O
 
   const getSharedObservables$ = (input: A): BehaviorObservable<O> => {
     for (let i = input.length - 1; input[i] === undefined && i > -1; i--) {
@@ -45,7 +48,7 @@ export default function connectFactoryObservable<A extends [], O>(
 
     const sharedObservable$ = shareLatest(
       getObservable(...input),
-      defaultValue,
+      getDefaultValue(...input),
       false,
       () => {
         cache.delete(keys)

packages/core/src/bind/index.ts

@@ -43,7 +43,7 @@ export function bind<T>(
  */
 export function bind<A extends unknown[], O>(
   getObservable: (...args: A) => Observable<O>,
-  defaultValue?: O,
+  defaultValue?: O | ((...args: A) => O),
 ): [(...args: A) => Exclude<O, typeof SUSPENSE>, (...args: A) => Observable<O>]
 
 export function bind(observable: any, defaultValue: any) {