Add wrapMethod function

[aleclarson]

The wrapMethod function replaces an existing method on an object with a custom-wrapped version.

Monkey-patching can be useful when dealing with rigid third-party APIs. This might be a bit too much syntactic sugar for Radashi, but I’m proposing it anyway because I believe wrapMethod makes the intended modification clearer.

Potential implementation

export function wrapMethod<T extends object, K extends keyof T>(
  obj: T,
  methodName: K,
  wrapper: T[K] extends (this: infer This, ...args: infer Args) => infer Result
    ? (this: This, original: T[K], args: Args) => Result
    : never,
): void {
  const original = obj[methodName] as T[K]
  obj[methodName] = function (this: any, ...args: any[]) {
    return wrapper.call(this, original, args)
  } as T[K]
}

Example

const obj = {
  greet(name: string) {
    return `Hello, ${name}!`;
  }
};

wrapMethod(obj, "greet", function (original, args) {
  return original.apply(this, args) + " How are you today?";
});

console.log(obj.greet("Alice")); 
// Output: "Hello, Alice! How are you today?"

[aleclarson]

Changed my mind on this one, but still open to community feedback.