From: Matt H <matt@...>
Date: 2009-11-30T04:50:56+09:00
Subject: Date class method `once` wraps original call in Array. Why?

I'm reading the Pickaxe and on page 391, there is a code listing for
the class method `once` from the Date module in Ruby:

  def once(*ids) #:nodoc:
    for id in ids
      module_eval <<-"end:"
        alias_method :__#{id.to_i}__, :#{id.to_s}
        private :__#{id.to_i}__
        def #{id.to_s}(*args, &block)
          puts "Inside once: \#{args.inspect}"
          (@__#{id.to_i}__ ||= [__#{id.to_i}__(*args, &block)])[0]
        end
      end:
    end
  end

I was wondering why the original method called is wrapped in an Array.
So I started digging the the source history hoping to find an
explanation. I found the commit that changed it to use the Array but
no explanation for the change. The commit where it was modified is
here:

<http://svn.ruby-lang.org/cgi-bin/viewvc.cgi/trunk/lib/date2.rb?r1=710&r2=709&pathrev=710>

I created a simple class and use the code with and without the Array
and it seems to work the same for my simple test. Just curious if I'm
not seeing something obvious.

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