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It’s all about finding out where Ruby’s syntax is flexible, isn’t it? So, did you know you can use instance variables or arbitrary code to set the defaults in your method parameters? All executed in the same context as your method.

 class LineArtist
   attr_accessor :distance, :thickness
   def draw( dist = @distance, thick = self.thickness ); end
end

And, check this out—you can refer to earlier parameters when setting defaults!

 class BlogEntry
   attr_accessor :author, :title, :created_at, :content
   def initialize( blog, title, content,
                   created_at = Time.now,
                   author = blog.default_author )
   end
 end

This is especially useful for methods where you’re passing in a set of paths. If some of the paths are deleted, you want to default to an earlier path (or a new path based on an earlier path.)

 class Blog
   def setup( path, template_path = File.join( path, "skel" ) )
   end
 end