From: Logan Capaldo <logancapaldo@...>
Date: 2007-02-06T05:06:49+09:00
Subject: Re: Enumerated Types

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On 2/5/07, Dan Stevens (IAmAI) <dan.stevens.iamai@gmail.com> wrote:
>
> It seems to me that I should simply be able to use symbols as values
> for my enumerated types, like for example:
>
> class Color
>
>   def initialize(color)
>     @color = color
>   end
>
>   def to_hex
>     case @color
>       when :red: 0xFF0000
>       when :green: 0x00FF00
>       when :blue: 0x0000FF
>       else @color
>     end
>   end
>
> end
>
> c = Color.new(:red)
> puts c.to_hex.to_s(16)
>
> Might there be any reason why I shouldn't do this, or am I quite fine
> doing this?


This is fine. You may want to use a hash to make life simpler though:
class Color
  HexValues = { :red  =>  0xFF0000, :green => 0x00FF00, :blue => 0x0000FF }
  def to_hex
     HexValues[@color] or @color
  end
end





On 03/02/07, Robert Klemme <shortcutter@googlemail.com> wrote:
> > On 03.02.2007 19:52, Dan Stevens (IAmAI) wrote:
> > > As part of a solution, I wish the value of an attribute to be one of a
> > > finite set of values, in other words I believe I want an 'enumerated
> > > type'. I've look at the 'Enumerable' and 'Enumerator' class and they
> > > appear to me to be unrelated to what I wish to achieve (correct me if
> > > I'm wrong).
> > >
> > > I could do the traditional method of named constants with integer
> > > values but I can't help feeling that there must be a class or some
> > > nice method of doing this. Any advice would be appreciated.
> >
> > I believe there are enum classes in the RAA.  If you do not want to use
> > them, symbols come pretty close:
> >
> > class YourClass
> >    YOUR_ENUM = [
> >      :old,
> >      :young,
> >      :unknown,
> >    ].freeze
> > end
> >
> > HTH
> >
> > Kind regards
> >
> >         robert
> >
> >
>
>

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