From: Romulo Ceccon <redmine@...>
Date: 2009-11-09T01:56:47+09:00
Subject: [ruby-core:26628] [Bug #2346] Array(nil) fails after redefining NilClass.method_missing to throw NoMethodError

Bug #2346: Array(nil) fails after redefining NilClass.method_missing to throw NoMethodError
http://redmine.ruby-lang.org/issues/show/2346

Author: Romulo Ceccon
Status: Open, Priority: Normal
Category: core
ruby -v: ruby 1.9.2dev (2009-11-08 trunk 25690) [i386-mswin32_90]

Given the following script:

  print "Array(nil) => ", Array(nil).inspect, "\n"
  print "Array.try_convert(nil) => ", Array.try_convert(nil).inspect, "\n"
  class NilClass
    private
    def method_missing(method, *args, &block)
      raise NoMethodError
    end
  end
  print "Array(nil) => ", Array(nil).inspect, "\n"
  print "Array.try_convert(nil) => ", Array.try_convert(nil).inspect, "\n"

Ruby 1.9.2dev returns this:

  $ ruby -v
  ruby 1.9.2dev (2009-11-08 trunk 25690) [i386-mswin32_90]

  $ ruby nil_ary.rb
  Array(nil) => []
  Array.try_convert(nil) => nil
  nil_ary.rb:6:in `method_missing': NoMethodError (NoMethodError)
          from nil_ary.rb:9:in `Array'
          from nil_ary.rb:9:in `<main>'

while for Ruby 1.8.8dev it is ok:

  $ ruby -v
  ruby 1.8.8dev (2009-10-31 revision 25583) [i386-mswin32_90]

  $ ruby nil_ary.rb
  Array(nil) => []
  Array.try_convert(nil) => nil
  Array(nil) => []
  Array.try_convert(nil) => nil

Ruby 1.9.1-p0 (Windows) also runs fine. I don't understand what is happening here, but the behavior change breaks Rails 2.3.4 because active_support/whiny_nil.rb redefines NilClass.method_missing with code equivalent to the above one.


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