From: David Smiley <dsmiley@...>
Date: 2006-02-28T02:05:17+09:00
Subject: parser bug, function call without parens across multiple lines

I have encountered a counter-intuitive bug in Ruby's parser.  The
following sample shows the problem:

puts Class.new do
   def to_s
      'no bug'
   end
end.new

What do you think the output should be?  I think it should clearly be
'no bug' but instead it is '#<Class:0x73be8>' and then an error
complaining that there is no method 'new' on 'NilClass'.  See, Ruby
invokes the call to 'new' AFTER the call to puts.  To work around this
problem, use of parenthesis are necessary.

This problem is NOT there if the code is on one line:

puts Class.new {def to_s ; 'no bug'; end }.new

The fact that this shows up for the multiple line but not the single
line sample should be a sign that there is indeed a problem.  And it
doesn't matter whether the brackets or do-end notation is used; the
results are the same.

I encountered this problem when I was using Rails to set the
around_filter of a controller by using an anonymous class.

I tested this against Ruby 1.8.4.

~ David Smiley
   MITRE