From: Robert Klemme <shortcutter@...>
Date: 2007-07-25T20:19:33+09:00
Subject: Re: Detecting singletons

2007/7/25, Lars Westergren <lars.westergren@ki.se>:
> 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?

If Singleton === obj
  puts "it's a singleton!"
end

Kind regards

robert