Issue #7027 has been updated by Hanmac (Hans Mackowiak). in my opinion Delegator should be improved so it shows that its a Tempfile, but is_a? should also show that its a File or IO ---------------------------------------- Bug #7027: Tempfile#inspect is Confusing https://bugs.ruby-lang.org/issues/7027#change-29540 Author: Glass_saga (Masaki Matsushita) Status: Open Priority: Normal Assignee: Category: lib Target version: ruby -v: ruby 2.0.0dev (2012-09-15 trunk 36975) [x86_64-linux] I think Tempfile#inspect is really confusing. It says Tempfile object is a File, but it is not a File object. % irb -r tempfile irb(main):001:0> t = Tempfile.new("hoge") => #<File:/tmp/hoge20120916-12354-uontdm> irb(main):002:0> t.is_a? File => false irb(main):003:0> see also (Japanese): http://r7kamura.hatenablog.com/entry/2012/09/05/194630 -- http://bugs.ruby-lang.org/