From: James Coglan <jcoglan@...>
Date: 2008-12-24T01:57:57+09:00
Subject: Re: Loading up a hash with variables if they are defined

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>
>  # Return a hash of the navigation parameters
>  def nav_params
>    params = {}
>
>    params[:prefix]      = @prefix      if @prefix
>    params[:category_id] = @category_id if @category_id
>    params[:page]        = @page        if @page
>
>    params
>  end
>
> I want to load a parameters hash with the contents of some instance
> variables, but only if they are defined.



params = [:prefix, :category_id, :page].inject({}) do |hash, name|
  var = instance_variable_get("@#{name}")
  hash[name] = var if var
  hash
end

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