From: Eli Bendersky <eliben@...>
Date: 2006-03-24T15:23:52+09:00
Subject: Verifying keyword arguments

Hello all,

I'm now writing my first real Ruby module, and on the second function I
already run into a pattern that seems to be very common.
I like using keyword arguments for methods, as follows:

def method(args)
  ...
end

And then call:

method(:arg1 => value1, :arg2 => value2)

And so on.
Now, often some arguments are compulsory, so I wrote the following code
to verify it:

def method(args)
  [:username, :password, :url].each do |arg|
    raise(ArgumentError, "Argument :#{arg} is compulsory" unless
args.has_key?(arg)
  end

  ...
end

I have two questions:
1) Is this the right/idiomatic/best way to achieve what I'm attempting
?
2) Is there a library that encapsulates this capability, or is everyone
writing one of his own ? Because if I don't find any, I surely will
write one... It should be enough saying:

verify_args(:username, :password, :url)

Instead of the .each do iteration everywhere 

Eli