Question for Avdi

gistfile1.md

When checking for valid input, we could raise an exception to make it more helpful to the developer doing the implementation.

Current code:

def initialize(params)
  super
 
  raise ArgumentError, "Must provide results base dir." unless params.has_key?("dir")
  @dir = params["dir"]
end

According to Confident Ruby it seems this is a bad pattern. The right pattern, would be the following:

def initialize(params)
  super
 
  @dir = params.fetch("dir")
rescue KeyError
  raise ArgumentError, "Must provide results base dir."
end

Is this correct? If so, our issue with this is what if something in super raises KeyError?

I have to think on this a bit. Let me continue using the philosophy and post a more thorough example when I come across one. Thanks for being helpful.