From: "Mariusz Pękala" <skoot@...>
Date: 2007-07-20T20:18:13+09:00
Subject: Re: enumeration with symbol name information

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On 2007-07-20 19:00:04 +0900 (Fri, Jul), Sasa wrote:
> Hello everybody...
> I have a beginne's question:
>=20
> I've created class for my numeric constants, it looks like:
>=20
> class MyClass
>=20
>   NAME1 =3D 0
>   NAME2 =3D 1
>   NAME3 =3D 2
>   #etc...
>=20
>   def self.to_s(something)
>     case something
>       when 0
>         "NAME1"
>       when 1
>         "NAME2"
>       when 2
>         "NAME3"
>       #etc...
>     end
>   end
>=20
> end
>=20
>=20
> What is more elegant way to do this? Basically, I want to convert the=20
> numerical value to string representation (ideally via identifier name).
>=20
> Thanks in advance,
> Sasa=20

If your numeric values always start from 0, then you may use an array:

class MyClass
  NAMES =3D [ 'NAME1','NAME2','NAME3' ]

  def self.to_s(something) # personally I would rather avoid redefining cla=
ss.to_s
    NAMES[something.to_i] || default_value
  end
end

If this is unacceptable, you may use a hash:

  NAMES =3D { 1 =3D> 'NAME1', 2 =3D> 'NAME2', 5 =3D> 'NAME3' }
  NUMBERS =3D Hash[ *NAMES.map {|k,v| [v,k]}.flatten ]    # may be useful :=
-)

  def self.to_s(something)
    NAMES[ something ] || defaul_value
  end

  def self.to_i(something)  # may be useful :-)
    NUMBERS[ something ] || default_number
  end

--=20
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