util.ts

// I wrote this in packages/util/misc in cocalc and copied it here.  -- William Stein

// TODO: this is also in python-wasm/src/util.ts -- refactor somewhere...

// Get *all* methods of an object (including from base classes!).
// See https://flaviocopes.com/how-to-list-object-methods-javascript/
// This is used by bind_methods below to bind all methods
// of an instance of an object, all the way up the
// prototype chain, just to be 100% sure!
function get_methods(obj: object): string[] {
  let properties = new Set<string>();
  let current_obj = obj;
  do {
    Object.getOwnPropertyNames(current_obj).map((item) => properties.add(item));
  } while ((current_obj = Object.getPrototypeOf(current_obj)));
  return [...properties.keys()].filter(
    (item) => typeof obj[item] === "function"
  );
}

// Bind all or specified methods of the object.  If method_names
// is not given, binds **all** methods.
// For example, in a base class constructor, you can do
//       bind_methods(this);
// and every method will always be bound even for derived classes
// (assuming they call super if they overload the constructor!).
// Do this for classes that don't get created in a tight inner
// loop and for which you want 'safer' semantics.
export function bind_methods<T extends object>(
  obj: T,
  method_names: undefined | string[] = undefined
): T {
  if (method_names === undefined) {
    method_names = get_methods(obj);
    method_names.splice(method_names.indexOf("constructor"), 1);
  }
  for (const method_name of method_names) {
    obj[method_name] = obj[method_name].bind(obj);
  }
  return obj;
}