From: Joel VanderWerf <vjoel@...>
Date: 2002-12-20T17:19:46+09:00
Subject: Re: determing defined constants for a class

Robert McGovern wrote:
> Okay so constants returns an array of the constant names as a string in 
> short form (i.e. not including the path needed to use them). Hmm, so 
> with the following sample code, if I want to verify that an method is 
> passed a valid constant argument what would I want to do? (given the 
> constant will be passed into the method as a numeric)

Have you considered using constants with a symbolic rather than numeric 
value?

         TRACK_LENGTH = :TRACK_LENGTH
         TRACK_TITLE = :TRACK_TITLE

Or, if you want to make sure that the only access to these values is 
through the ID3::V2::Frame scope, you could create some objects:

         TRACK_LENGTH = Object.new
         TRACK_TITLE = Object.new

In this case, the array

   Frame.constants.map{|c|Frame.class_eval(c)}

will let you check if a given objects is one of your allowed constants. 
(You might consider a hash for this, if it's going to be large.)