I have a fairly large and complex object graph of Value Objects created
by soap4r and used in a Rails application. The app, which used to work,
now gets
Exception `TypeError' at
/usr/local/lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/active_record/transactions.rb:97
- singleton can't be dumped
all over the place and I have narrowed it down to Marshal.dump being
used by Rails.

I have aliased Marshal.dump so that I can inspect the objects passed
first, I thought that would be the fastest way to locate the problematic
object. My question is, how do I detect that an object is a singleton?
Should I test with "responds_to?" if the "new" method lacking or that
the "instance" method is there? Or is there an easier way?

Thanks in advance,
Lars