A little while ago, I suggested to add Ecto.Changeset.optimistic_lock/4 in addition to the already existing Ecto.Changeset.optimistic_lock/3. While José didn’t like the idea, he also pointed out that if he were to consider it, he’d prefer modifying the API so that it would accept an opts Keyword list instead of adding optimistic_lock/4.
Ever since that, I have been wondering: When is it preferable to use an opts Keyword list instead of additional function parameters? What criteria do you usually use to decide which one to pick?
In many cases so far, I have found Keyword lists to be less convenient than »regular« parameters since you can’t do pattern matching on them.
My impression is that they might be better for public-facing interfaces in order to have a cleaner API. I’d then extract the values in the public function and work with them in additional private functions where pattern matching can be used again. What are your thoughts on this? Any rules of thumb that you employ when making the decision?
