method_missing & Ghost Methods

The last stop in method lookup

Remember the ancestor chain from module 24? When Ruby walks it and finds nothing, it doesn't give up — it sends the object one more message: method_missing(name, args). The default implementation raises NoMethodError. But override it, and you can respond to methods that don't exist* — "ghost methods." This is how find_by_email_and_status works in Rails without anyone defining it.

In an interview, say: "method_missing is the hook Ruby calls when method lookup fails. Overriding it lets an object answer messages it has no explicit method for — the basis of ActiveRecord's dynamic finders and OpenStruct — as long as you pair it with respond_to_missing?."