Add: NullDriver return value type is never

Author: Vovan-VE

CHANGELOG.md

@@ -1,7 +1,11 @@
 # Changelog
 
-## 0.4.1 (DEV)
+## 0.5.0 (2023-12-16)
 
+- Add: A 3rd optional generic parameter `VOut` to all of `StoreDriver`
+  interfaces to declare what can be returned.
+- Upd: `createNullDriver` now returns driver with `VOut` set to `never` for
+  better types inference.
 - Fix: `createLocalStorageDriver` didn't use `serialize` and `unserialize`.
 
 ## 0.4.0 (2023-12-06)

README.md

@@ -14,13 +14,13 @@ npm i @cubux/storage-driver
 
 ## API
 
-### `interface StoreDriverSingle<K, V>`
+### `interface StoreDriverSingle<K, V, VOut = V>`
 
 Driver interface to read/write data by single item.
 
 #### Methods
 
-##### `getItem(key: K): Promise<V | undefined>`
+##### `getItem(key: K): Promise<VOut | undefined>`
 
 Get value of specific item with the given key.
 
@@ -32,13 +32,13 @@ Remove item with the given key.
 
 Store the given value in item with the given key.
 
-### `interface StoreDriverMapped<K, V>`
+### `interface StoreDriverMapped<K, V, VOut = V>`
 
 Driver interface to read/write all items at once.
 
 #### Methods
 
-##### `getAll(): Promise<ReadonlyMap<K, V>>`
+##### `getAll(): Promise<ReadonlyMap<K, VOut>>`
 
 Get all items.
 
@@ -47,7 +47,7 @@ Get all items.
 Replace all stored items with the given new items. That is keys became missing
 will be removed from storage.
 
-### `interface StoreDriver<K, V>`
+### `interface StoreDriver<K, V, VOut = V>`
 
 Generalized interface covering all specific interfaces above.
 
@@ -101,5 +101,5 @@ actual driver. This driver always contains nothing in reads and does nothing on
 writes.
 
 ```ts
-function createNullDriver<K = any, V =  any>(): StoreDriver<K, V>
+function createNullDriver<K = any, V = any>(): StoreDriver<K, V, never>
 ```

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@cubux/storage-driver",
-  "version": "0.4.0",
+  "version": "0.5.0",
   "description": "Simple storage driver abstraction.",
   "keywords": [
     "storage",

src/null.ts

@@ -11,21 +11,21 @@ interface CreateNullDriverFn {
    * omit actual driver. This driver always contains nothing in reads and does
    * nothing on writes.
    */
-  <K, V>(): StoreDriver<K, V>;
+  <K, V>(): StoreDriver<K, V, never>;
 
   /**
    * Create dummy no-op driver. Can be used for example in test environment to
    * omit actual driver. This driver always contains nothing in reads and does
    * nothing on writes.
    */
-  <K>(): StoreDriver<K, any>;
+  <K>(): StoreDriver<K, any, never>;
 
   /**
    * Create dummy no-op driver. Can be used for example in test environment to
    * omit actual driver. This driver always contains nothing in reads and does
    * nothing on writes.
    */
-  (): StoreDriver<any, any>;
+  (): StoreDriver<any, any, never>;
 }
 
 /**
@@ -35,7 +35,7 @@ interface CreateNullDriverFn {
  */
 export const createNullDriver: CreateNullDriverFn = () => new NullDriver();
 
-class NullDriver implements StoreDriver<any, any> {
+class NullDriver implements StoreDriver<any, any, never> {
   getItem(key: any) {
     return Promise.resolve(undefined);
   }
@@ -46,7 +46,7 @@ class NullDriver implements StoreDriver<any, any> {
     return Promise.resolve();
   }
   getAll() {
-    return Promise.resolve(new Map());
+    return Promise.resolve(new Map<any, never>());
   }
   setAll(items: ReadonlyMap<any, any>) {
     return Promise.resolve();

src/types.ts

@@ -1,11 +1,11 @@
 /**
  * Driver interface to read/write data by single item.
  */
-export interface StoreDriverSingle<K, V> {
+export interface StoreDriverSingle<K, V, VOut extends V = V> {
   /**
    * Get value of specific item with the given key.
    */
-  getItem(key: K): Promise<V | undefined>;
+  getItem(key: K): Promise<VOut | undefined>;
   /**
    * Remove item with the given key.
    */
@@ -19,11 +19,11 @@ export interface StoreDriverSingle<K, V> {
 /**
  * Driver interface to read/write all items at once.
  */
-export interface StoreDriverMapped<K, V> {
+export interface StoreDriverMapped<K, V, VOut extends V = V> {
   /**
    * Get all items.
    */
-  getAll(): Promise<ReadonlyMap<K, V>>;
+  getAll(): Promise<ReadonlyMap<K, VOut>>;
   /**
    * Replace all stored items with the given new items. That is keys became
    * missing will be removed from storage.
@@ -34,6 +34,6 @@ export interface StoreDriverMapped<K, V> {
 /**
  * Generalized interface covering all specific interfaces.
  */
-export interface StoreDriver<K, V>
-  extends StoreDriverSingle<K, V>,
-    StoreDriverMapped<K, V> {}
+export interface StoreDriver<K, V, VOut extends V = V>
+  extends StoreDriverSingle<K, V, VOut>,
+    StoreDriverMapped<K, V, VOut> {}