From: Dido Sevilla <dido.sevilla@...>
Date: 2005-05-27T15:10:49+09:00
Subject: Methods with lots of arguments

Just went through a bit of refactoring on a bit of Ruby code that I've
been writing, and have been following some of the guidelines here:

http://rpa-base.rubyforge.org/wiki/wiki.cgi?GoodAPIDesign

I've had a lot of methods in the old code that had lots and lots of
arguments, and many of which had default values, and followed the
suggestion on naming arguments by passing what is essentially a hash.
The syntax for this looked a lot like the labeled arguments used in
OCaml, and it seems like a good way of doing things.  Now only if Ruby
had actual support for this idiom. As it turns out, I wind up writing
a lot of methods that look like this:

def somemethod(args)
  requiredargs = [ :foo, :bar, :baz ]
  defaultargs = { :quux => nil, :blargle => nil }
  requiredargs.each {
    |arg|
    unless (args.has_key?(arg))
      raise ArgumentError.new("missing required argument #{arg.to_s}")
    end
  }
  newargs = defaultargs.merge(args)
  ...
end

Is there at the very least some kind of library out there that can do
all of this checking and merging automatically? If there is one, I
think it should be mentioned in the RPA-base link. However, I think
that this kind of idiom would be better as an official part of Ruby
syntax.