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Groups > comp.lang.ruby > #2805

Re: Copying parameters to singleton class

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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/.

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Thread

Copying parameters to singleton class Lars Olsson <lasso@lassoweb.se> - 2011-04-11 02:19 -0700
  Re: Copying parameters to singleton class Robert Klemme <shortcutter@googlemail.com> - 2011-04-11 04:34 -0500
    Re: Copying parameters to singleton class 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-11 21:21 -0500
    Re: Copying parameters to singleton class 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-11 21:05 -0500
      Re: Copying parameters to singleton class Robert Klemme <shortcutter@googlemail.com> - 2011-04-12 01:53 -0500
        Re: Copying parameters to singleton class 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-12 13:31 -0500
    Re: Copying parameters to singleton class 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-12 19:08 -0500
  Re: Copying parameters to singleton class Jesús Gabriel y Galán <jgabrielygalan@gmail.com> - 2011-04-11 04:36 -0500
    Re: Copying parameters to singleton class Lars Olsson <lasso@lassoweb.se> - 2011-04-11 02:53 -0700
  Re: Copying parameters to singleton class 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-11 21:48 -0500
    Re: Copying parameters to singleton class Robert Klemme <shortcutter@googlemail.com> - 2011-04-12 02:00 -0500
      Re: Copying parameters to singleton class Lars Olsson <lasso@lassoweb.se> - 2011-04-12 01:25 -0700
        Re: Copying parameters to singleton class Robert Klemme <shortcutter@googlemail.com> - 2011-04-12 03:51 -0500
        Re: Copying parameters to singleton class 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-12 13:14 -0500
          Re: Copying parameters to singleton class 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-12 13:38 -0500
      Re: Copying parameters to singleton class 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-12 13:43 -0500
  Re: Copying parameters to singleton class 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-12 19:29 -0500
    Re: Copying parameters to singleton class Lars Olsson <lasso@lassoweb.se> - 2011-04-13 01:49 -0700
  Re: Copying parameters to singleton class 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-13 19:32 -0500
  Re: Copying parameters to singleton class 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-13 19:49 -0500
    Re: Copying parameters to singleton class 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-13 20:09 -0500
      Re: Copying parameters to singleton class Lars Olsson <lasso@lassoweb.se> - 2011-04-14 01:33 -0700
        Re: Copying parameters to singleton class 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-14 12:07 -0500

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