no-arg-error-in-192.sh

ruby-1.9.2-p0 > class Foo; end
#=> nil 
ruby-1.9.2-p0 > Foo.new('bar')
#=> #<Foo:0x00000100974e50> 
ruby-1.9.2-p0 > class Foo; end
 => nil 
ruby-1.9.2-p0 > Foo.new(1,2)
 => #<Foo:0x000001009dd4a0> 
ruby-1.9.2-p0 > Foo.new(1,2,3, :a => 'b')
 => #<Foo:0x0000010181b918> 
ruby-1.9.2-p0 > class Foo; def initialize; end; end
 => nil 
ruby-1.9.2-p0 > Foo.new(1,2,3, :a => 'b')
ArgumentError: wrong number of arguments (4 for 0)
	from (irb):5:in `initialize'
	from (irb):6:in `new'
	from (irb):6
	from /Users/david/.rvm/rubies/ruby-1.9.2-p0/bin/irb:17:in `<main>'

It's a recipe for bugs. If you're using a library incorrectly, passing in args when it doesn't take them, it will silently accept those args and result in failures/errors downstream.

The problem, btw, is that the earlier examples allow you to pass in args that are unexpected - not that the last example raises an error (that's what should happen in the earlier examples, in my view).

So what do you think should be the arity on Object#new?

0, as it is in ruby-1.8.