From: ts <decoux@...>
Date: 2001-11-07T20:58:13+09:00
Subject: [ruby-talk:24501] Re: List of Exception classes

>>>>> "R" == Rube  <usenet@neo.rr.com> writes:

R> I mean no disrespect, but the online version of the PP book doesn't
R> list the hierarchy ("figure not available").  Ought one be required to
R> purchase a commercial text to obtain the exception classes in the ruby
R> language?  This seems like information that ought to be freely
R> available- requiring dead-tree reference material to learn something
R> this basic about the language will discourage it's popularity, and
R> ultimately, the sale of ruby texts.

 Well, ruby is a programming language that means that it's OK to use it for
 writing programs :-)

pigeon% cat b.rb
#!/usr/bin/ruby
class Hier < Hash
   def initialize klass = Object
      @kl, cl = klass
      ObjectSpace.each_object(Class) do |obj|
         if obj < klass
            anc = obj.ancestors
            (anc.shift && anc).each {|cl| break if cl.kind_of? Class }
            (self[cl] ||= []).push obj
         end
      end
   end

   def display cl = @kl, level = 0
      print "   " * level, cl, "\n"
      (self[cl] || []).each {|obj| display obj, level + 1}
   end
end

Hier.new(Exception).display ScriptError

pigeon% b.rb
ScriptError
   NotImplementedError
   LoadError
   NameError
   SyntaxError
pigeon% 



Guy Decoux