Issue #8173 has been reported by hasari (Hiro Asari). ---------------------------------------- Bug #8173: 2-arg form of Time.at can take a Time as either argument https://bugs.ruby-lang.org/issues/8173 Author: hasari (Hiro Asari) Status: Open Priority: Normal Assignee: Category: Target version: ruby -v: ruby 2.1.0dev (2013-03-11 trunk 39724) [x86_64-darwin12.2.1] http://www.ruby-doc.org/core-2.0/Time.html#method-c-at shows 3 forms of invocation: at(time) ??? time click to toggle source at(seconds_with_frac) ??? time at(seconds, microseconds_with_frac) ??? time But the last form can take a Time as either argument (and converts to a numeric value represented by the number of seconds since the Epoch). If a Time is used as the second argument, the numeric value is then converted to microseconds to return a Time. (I hope that I'm making sense.) irb(main):001:0> RUBY_DESCRIPTION => "ruby 2.1.0dev (2013-03-11 trunk 39724) [x86_64-darwin12.2.1]" irb(main):002:0> t1=Time.at(10) => 1969-12-31 19:00:10 -0500 irb(main):003:0> t2=Time.at(t1,t1) => 1969-12-31 19:00:10 -0500 irb(main):004:0> t2.usec => 10 Is this intended behavior? If so, the documentation should be updated. 1.9.3 behaves the same way. -- http://bugs.ruby-lang.org/