test_method_shadow.rb

class Foo
  def foo; "abc" end

  # this default param should resolve at runtime to the #foo method call
  def run(foo = foo)
    p foo # print shadowed local var defaulting to attr value
  end
end

puts "Testing #{RUBY_VERSION}:"
Foo.new.run

__END__

$ rvm all do ruby test_method_shadow.rb
Testing 1.8.7:
"abc"
Testing 1.9.2:
"abc"
Testing 1.9.3:
"abc"
Testing 2.0.0:
"abc"
Testing 2.1.1:
"abc"
Testing 2.1.2:
"abc"
Testing 2.1.3:
"abc"
Testing 2.2.0:
nil
$

I think this is a good change - I was never sure what would happen if I did this.

A better change would be for it to throw an error.

def foo
  "abc"
end

foo = foo

puts "Testing #{RUBY_VERSION}:"
p foo

# Testing 2.0.0:
# nil

Well damn. I'd still consider this surprising, but I guess this makes it more consistent. Hmm. 😟