If you use simple data structures without logic, it is basically what he is saying. Basically `createAuthorData` is a data structure constructor. There are some advantages by using _.pick or something in JS land, but these don't work for other more strictly typed languages.

Also, I would be careful with using it so much as his example:

``` function createAuthorData(firstName, lastName, books) { return {firstName: firstName, lastName: lastName, books: books}; }

function fullName(data) { return data.firstName + " " + data.lastName; }

function createArtistData(firstName, lastName, genre) { return {firstName: firstName, lastName: lastName, genre: genre}; } ```

you can also do `fullName({firstName: 'Elmond', not:'really'})` and have an hard to catch bug (where an actual typesystem would catch it).

You can either use a Protocol for this (PersonName) or a base class (though those are going out of fashion nowadays)