From: James Edward Gray II <james@...>
Date: 2005-08-19T23:56:51+09:00
Subject: Re: Case Expressions and Classes

On Aug 19, 2005, at 9:51 AM, Daniel Schierbeck wrote:

> Could anyone explain to me why this isn't working?
>
>     # returns 'no'
>     case :foo.class
>       when Symbol then
>         puts 'yes'
>       else
>         puts 'no'
>     end

Cases use ===() to do the check in when.  The ===() for class checks  
to see if the passed object is of that class.  The object you are  
using in the case above is Symbol, which is an object of the class  
Class, not the class Symbol you are testing for.

Put another way, you're outsmarting Ruby's very intelligent case  
statement.  Let it do all the work:

     # returns 'yes'
     case :foo
       when Symbol
         puts 'yes'
       else
         puts 'no'
     end

Hope that helps.

James Edward Gray II