From: Walter Szewelanczyk <walter@...>
Date: 2004-09-03T05:50:46+09:00
Subject: Re: Not just $SAFE, but damn $SAFE

Aredridel wrote:

>> Sincerely I don't understand (I know, I'm stupid) but why don't you define
>> classes that you want to trust and give a result only when an object
>> belong to theses classes ?
> 
> 
> The problem is in finding out what class something is.
> 
> obj.class # Bad -- class can be overridden to be evil
> 
> obj.instance_of? # Bad -- same as #class
> 
> Class === obj # Bad, because you can define an evil subclass.
> 
> 
> 

To find the class you can use :

class ClassFinder
   @@classCall = Object.instance_method(:class)
   def ClassFinder.class(obj)
     @@classCall.bind(obj).call
   end
end

class Bad
   def class
     Object
   end
end

puts Bad.new.class
puts ClassFinder.class(Bad.new)

outputs :
Object
Bad


Walt

-- 
Walter Szewelanczyk
IS Director
M.W. Sewall & CO.        email : walter@mwsewall.com
259 Front St.            Phone : (207) 442-7994 x 128
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