Memo Decorator

This decorator applies memoization to a method of a class.

Usage

Apply the decorator to a method of a class. The cache is local for the method but shared among all instances of the class. Strongly recommend you to use this decorator only on pure methods.

Installation:

``shell
npm i memo-decorator --save
`

$3

`ts
export interface Config {
resolver?: Resolver;
cache?: MapLike;
}
`

- Resolver is a function, which returns the key to be used for given set of arguments. By default, the resolver will use the first argument of the method as the key.
- MapLike is a cache instance. By default, the library would use Map.

Example:

`typescript
import memo from 'memo-decorator';

class Qux {
@memo({
resolver: (...args: any[]) => args[1],
cache: new WeakMap()
})
foo(a: number, b: number) {
return a * b;
}
}
`

$3

`typescript
import memo from 'memo-decorator';

class Qux {
@memo()
foo(a: number) {
console.log('foo: called');
return 42;
}

@memo({
resolver: _ => 1
})
bar(a: number) {
console.log('bar: called');
return 42;
}
}

const a = new Qux();
// Create a new cache entry and associate 1 with the result 42.
a.foo(1);
// Do not invoke the original method foo because there's already a cache
// entry for the key 1 associated with the result of the method.
a.foo(1);
// Invoke the original foo because the cache doesn't contain an entry
// for the key 2.
a.foo(2);

// Invoke bar and return the result 42 gotten from the original bar implementation.
a.bar(1);
// Does not invoke the original bar implementation because of the specified resolver
// which is passed to memo. For any arguments of the function, the resolver will return
// result 1 which will be used as the key.
a.bar(2);

const b = new Qux();
// Does not invoke the method foo because there's already an entry
// in the cache which associates the key 1 to the result 42 from the
// invocation of the method foo by the instance a.
b.foo(1);

// Outputs:
// foo: called
// foo: called
// bar: called
``

License

MIT