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From: 7stud -- <bbxx789_05ss@yahoo.com>
Newsgroups: comp.lang.ruby
Subject: Re: Copying parameters to singleton class
Date: Wed, 13 Apr 2011 20:09:40 -0500
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7stud -- wrote in post #992632:
> Try something like this:
>
>    def using(new_options)
>       Class.new(self) do
>         old_options = superclass.options
>         common_keys = old_options.keys & new_options.keys
>
>         common_keys.each do |key|
>           old_options[key] = new_options[key]
>         end
>
>         @options = old_options
>         @options.freeze
>       end
>     end

Whoops.  That doesn't work:

prog.rb:18:in `[]=': can't modify frozen hash (RuntimeError)

Hmmm...why can you merge() but not directly assign to individual keys 
when a hash is frozen?

Ok, merge() with some better variable names:

   def using(new_options)
      Class.new(self) do
        old_options = superclass.options

        @options = old_options.merge(new_options).select do |key|
           old_options.has_key?(key)
        end.freeze
      end
    end

-- 
Posted via http://www.ruby-forum.com/.