feat(bind): nested keys accept optional args

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

@@ -127,6 +127,13 @@ describe("connectFactoryObservable", () => {
       expect(result.current).toBe(2)
     })
 
+    it("handles optional args correctly", () => {
+      const [, getNumber$] = bind((x: number, y?: number) => of(x + (y ?? 0)))
+
+      expect(getNumber$(5)).toBe(getNumber$(5, undefined))
+      expect(getNumber$(6, undefined)).toBe(getNumber$(6))
+    })
+
     it("suspends the component when the factory-observable hasn't emitted yet.", async () => {
       const [useDelayedNumber] = bind((x: number) => of(x).pipe(delay(50)))
       const Result: React.FC<{ input: number }> = (p) => (

packages/core/src/bind/connectFactoryObservable.ts

@@ -6,6 +6,74 @@ import { useObservable } from "../internal/useObservable"
 import { SUSPENSE } from "../SUSPENSE"
 import { takeUntilComplete } from "../internal/take-until-complete"
 
+/**
+ * Accepts: A factory function that returns an Observable.
+ *
+ * Returns [1, 2]
+ * 1. A React Hook function with the same parameters as the factory function.
+ *  This hook will yield the latest update from the observable returned from
+ *  the factory function.
+ * 2. A `sharedLatest` version of the observable generated by the factory
+ *  function that can be used for composing other streams that depend on it.
+ *  The shared subscription is closed as soon as there are no subscribers to
+ *  that observable.
+ *
+ * @param getObservable Factory of observables. The arguments of this function
+ *  will be the ones used in the hook.
+ * @param unsubscribeGraceTime (= 200): Amount of time in ms that the shared
+ *  observable should wait before unsubscribing from the source observable when
+ *  there are no new subscribers.
+ *
+ * @remarks If the Observable doesn't synchronously emit a value upon the first
+ * subscription, then the hook will leverage React Suspense while it's waiting
+ * for the first value.
+ */
+export default function connectFactoryObservable<A extends [], O>(
+  getObservable: (...args: A) => Observable<O>,
+  unsubscribeGraceTime: number,
+): [
+  (...args: A) => Exclude<O, typeof SUSPENSE>,
+  (...args: A) => Observable<O>,
+] {
+  const cache = new NestedMap<A, [Observable<O>, BehaviorObservable<O>]>()
+
+  const getSharedObservables$ = (
+    input: A,
+  ): [Observable<O>, BehaviorObservable<O>] => {
+    for (let i = input.length - 1; input[i] === undefined && i > -1; i--) {
+      input.splice(-1)
+    }
+    const keys = ([input.length, ...input] as any) as A
+    const cachedVal = cache.get(keys)
+
+    if (cachedVal !== undefined) {
+      return cachedVal
+    }
+
+    const sharedObservable$ = shareLatest(getObservable(...input), () => {
+      cache.delete(keys)
+    })
+
+    const reactObservable$ = reactEnhancer(
+      sharedObservable$,
+      unsubscribeGraceTime,
+    )
+
+    const result: [Observable<O>, BehaviorObservable<O>] = [
+      takeUntilComplete(sharedObservable$),
+      reactObservable$,
+    ]
+
+    cache.set(keys, result)
+    return result
+  }
+
+  return [
+    (...input: A) => useObservable(getSharedObservables$(input)[1]),
+    (...input: A) => getSharedObservables$(input)[0],
+  ]
+}
+
 class NestedMap<K extends [], V extends Object> {
   private root: Map<K, any>
   constructor() {
@@ -51,69 +119,3 @@ class NestedMap<K extends [], V extends Object> {
     }
   }
 }
-
-const emptyInput = [0]
-/**
- * Accepts: A factory function that returns an Observable.
- *
- * Returns [1, 2]
- * 1. A React Hook function with the same parameters as the factory function.
- *  This hook will yield the latest update from the observable returned from
- *  the factory function.
- * 2. A `sharedLatest` version of the observable generated by the factory
- *  function that can be used for composing other streams that depend on it.
- *  The shared subscription is closed as soon as there are no subscribers to
- *  that observable.
- *
- * @param getObservable Factory of observables. The arguments of this function
- *  will be the ones used in the hook.
- * @param unsubscribeGraceTime (= 200): Amount of time in ms that the shared
- *  observable should wait before unsubscribing from the source observable when
- *  there are no new subscribers.
- *
- * @remarks If the Observable doesn't synchronously emit a value upon the first
- * subscription, then the hook will leverage React Suspense while it's waiting
- * for the first value.
- */
-export default function connectFactoryObservable<A extends [], O>(
-  getObservable: (...args: A) => Observable<O>,
-  unsubscribeGraceTime: number,
-): [
-  (...args: A) => Exclude<O, typeof SUSPENSE>,
-  (...args: A) => Observable<O>,
-] {
-  const cache = new NestedMap<A, [Observable<O>, BehaviorObservable<O>]>()
-
-  const getSharedObservables$ = (
-    input: A,
-  ): [Observable<O>, BehaviorObservable<O>] => {
-    const keys = input.length > 0 ? input : (emptyInput as A)
-    const cachedVal = cache.get(keys)
-
-    if (cachedVal !== undefined) {
-      return cachedVal
-    }
-
-    const sharedObservable$ = shareLatest(getObservable(...input), () => {
-      cache.delete(keys)
-    })
-
-    const reactObservable$ = reactEnhancer(
-      sharedObservable$,
-      unsubscribeGraceTime,
-    )
-
-    const result: [Observable<O>, BehaviorObservable<O>] = [
-      takeUntilComplete(sharedObservable$),
-      reactObservable$,
-    ]
-
-    cache.set(keys, result)
-    return result
-  }
-
-  return [
-    (...input: A) => useObservable(getSharedObservables$(input)[1]),
-    (...input: A) => getSharedObservables$(input)[0],
-  ]
-}

packages/core/src/bind/index.ts

@@ -46,18 +46,12 @@ export function bind<T>(
  * subscription, then the hook will leverage React Suspense while it's waiting
  * for the first value.
  */
-export function bind<
-  A extends (number | string | boolean | null | Object | Symbol)[],
-  O
->(
+export function bind<A extends unknown[], O>(
   getObservable: (...args: A) => Observable<O>,
   unsubscribeGraceTime?: number,
 ): [(...args: A) => Exclude<O, typeof SUSPENSE>, (...args: A) => Observable<O>]
 
-export function bind<
-  A extends (number | string | boolean | null | Object | Symbol)[],
-  O
->(
+export function bind<A extends unknown[], O>(
   obs: ((...args: A) => Observable<O>) | Observable<O>,
   unsubscribeGraceTime = 200,
 ) {