Allow define.ttl to be a number or function in the typescript definitions (#58)

Author: thomaspeklak

index.d.ts

@@ -82,17 +82,17 @@ declare class Cache {
   );
 
 
-  define(
+  define<T extends (...args: any[]) => any>(
     name: string,
     opts: {
       storage?: StorageOptionsType;
       transformer?: DataTransformer;
-      ttl?: number;
+      ttl?: number | ((result: Awaited<ReturnType<T>>) => number);
       stale?: number;
       serialize?: (...args: any[]) => any;
       references?: (...args: any[]) => References | Promise<References>;
     } & Events,
-    func?: (...args: any[]) => any
+    func?: T
   ): void;
   define(
     name: string,

index.test-d.ts

@@ -39,6 +39,7 @@ const fetchSomething = async (k: any) => {
 export type CachedFunctions = {
   fetchSomething: typeof fetchSomething;
   fetchSomethingElse: typeof fetchSomething;
+  fetchSomethingElseWithTtlFunction: typeof fetchSomething;
 };
 
 const unionMemoryCache = createCache({
@@ -55,6 +56,10 @@ expectType<typeof fetchSomething>(unionMemoryCache.fetchSomething);
 unionMemoryCache.define("fetchSomethingElse", { ttl: 1000, stale: 1000}, fetchSomething);
 expectType<typeof fetchSomething>(unionMemoryCache.fetchSomethingElse);
 
+unionMemoryCache.define("fetchSomethingElseWithTtlFunction", { ttl: (result) => result.k ? 1000 : 5, stale: 1000}, fetchSomething);
+expectType<typeof fetchSomething>(unionMemoryCache.fetchSomethingElseWithTtlFunction);
+
+
 const result = await unionMemoryCache.fetchSomething("test");
 expectType<{ k: any }>(result);