From: "ara.t.howard" <ara.t.howard@...>
Date: 2008-08-14T07:45:28+09:00
Subject: Re: case statement and ranges


On Aug 13, 2008, at 4:21 PM, Mini Skirt wrote:

> Hey, I want to do something like that:
>
> case amount
> when 25..50: 42
> when 51..66: 78
> when 90..123: 99
> end
>
> which works of course.
>
> Now what I would like to have some other cases like when amount is  
> lower
> that 25, but with no minimum, or when it is higher that 123 ...
> I could write something like:

the basis of a solution:



cfp:~ > cat a.rb

case 42
   when all(:a, :b, :c)
     puts 'nope'

   when any(42, 43, 44)
     puts 'forty-two'
end


case 42
   when any
     puts 42
end


case 42.0
   when any( 25 .. 50, any )
     p 42.0
   when 51 .. 66
   when 90 .. 123
end

case 4.2
   when any( 25 .. 50, any )
     p 4.2
   when 51 .. 66
   when 90 .. 123
end


BEGIN {

   class Pattern < ::Array
     def initialize *elements
       replace elements unless elements.empty?
     end

     def inspect
       "#{ self.class.name }#{ super }"
     end

     class Any < Pattern
       def === other
         return true if empty?
         any?{|element| element === other}
       end
       alias_method '==', '==='
     end

     class All < Pattern
       def === other
         return false if empty?
         all?{|element| element === other}
       end
       alias_method '==', '==='
     end
   end

   def all(*a, &b) Pattern::All.new(*a, &b) end
   def any(*a, &b) Pattern::Any.new(*a, &b) end

}

cfp:~ > ruby a.rb
forty-two
42
42.0
4.2



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better. simply reflect on that.
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