## Usage
### `CachedFactory`
`cached-factory` exports a `CachedFactory` class that takes in "factory" function in its constructor.
Each time a factory's `.get(key)` is called with any `key` for the first time, that factory is used to create a value under the `key`.
```ts
import { CachedFactory } from "cached-factory";
const cache = new CachedFactory((key) => `Cached: ${key}!`);
// "Cached: apple!"
cache.get("apple");
```
Values are cached so that subsequent `.get(key)` calls with the same `key` instantly return the same value.
```ts
import { CachedFactory } from "cached-factory";
const cache = new CachedFactory((key) => ({ key }));
// { key: "banana" }
cache.get("banana");
// true
cache.get("banana") === cache.get("banana");
```
### `WeakCachedFactory`
The package also exports a `WeakCachedFactory` class that provides the same behavior as `CachedFactory` but uses a `WeakMap` as its underlying data structure.
As such, only objects can be used for keys (no primitives), and there is no `entries()` function.
```ts
import { WeakCachedFactory } from "cached-factory";
const cache = new WeakCachedFactory((key: Context) =>
createSomeResultObject(key),
);
const result = cache.get(someContext);
// true
result === cache.get(someContext);
```
## Asynchronous Factories
`CachedFactory` does not itself handle `Promise` logic, but it doesn't have to!
Provided factory functions can themselves be `async` / return `Promise` values.
```ts
const cache = new CachedFactory(
async (key) => await fetch(`/some/resource?key=${key}`),
);
// Type: Promise
cache.get("cherry");
// Type: Response
await cache.get("cherry");
```
### Other Methods
#### `clear`
Clears the cache.
```ts
cache.clear();
```
### TypeScript
`cached-factory` is written in TypeScript and ships with strong typing.
๐ช
> ๐ Tip: if you're working with [`noImplicitAny`](https://aka.ms/tsconfig#noImplicitAny) enabled _(which is generally a good idea)_, an inline function provided as an argument to `CachedFactory` may need an explicit type annotation for its key.
>
> ```ts
> new CachedFactory((key: string) => `Cached: ${key}!`);
> ```
## Development
See [`.github/CONTRIBUTING.md`](./.github/CONTRIBUTING.md), then [`.github/DEVELOPMENT.md`](./.github/DEVELOPMENT.md).
Thanks! ๐ญ
## Contributors
> ๐ This package was templated with [`create-typescript-app`](https://github.com/JoshuaKGoldberg/create-typescript-app) using the [Bingo framework](https://create.bingo).
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_Source: https://npm.io/package/cached-factory ยท Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._
