zlib's being a little bitch

gistfile1.rb

require 'zlib'

d = Zlib::Deflate.new
d.set_dictionary("foo")
s = d.deflate("foo" * 100, Zlib::FINISH)

i = Zlib::Inflate.new
begin
  puts "Trying to set dictionary pre-emptively"
  i.set_dictionary("foo")
  puts i.inflate(s)
rescue Zlib::StreamError
  puts "CRAP - got a StreamError"
end

begin
  i.inflate(s)
rescue Zlib::NeedDict
  puts "Trying to set the dictionary after handling the NeedDict"
  i.set_dictionary("foo")
  puts i.inflate(s)
  puts "BOOM"
end