From: "rosenfeld (Rodrigo Rosenfeld Rosas)" Date: 2013-12-12T00:33:21+09:00 Subject: [ruby-core:59059] [CommonRuby - Feature #8257] Exception#cause to carry originating exception along with new one Issue #8257 has been updated by rosenfeld (Rodrigo Rosenfeld Rosas). I believe you think I should write this instead: raise WrappedException.new("message"), cause: ex I wouldn't mind doing that but if I ever had to store the exception without raising it then it wouldn't be possible to do so, right? But in that case I could also store the cause separately, so it isn't really a big deal. I wouldn't mind to add cause just to raise... ---------------------------------------- Feature #8257: Exception#cause to carry originating exception along with new one https://bugs.ruby-lang.org/issues/8257#change-43616 Author: headius (Charles Nutter) Status: Open Priority: Normal Assignee: matz (Yukihiro Matsumoto) Category: Target version: Ruby 2.1.0 Often when a lower-level API raises an exception, we would like to re-raise a different exception specific to our API or library. Currently in Ruby, only our new exception is ever seen by users; the original exception is lost forever, unless the user decides to dig around our library and log it. We need a way to have an exception carry a "cause" along with it. Java has getCause/setCause and standard constructors that take a cause exception. Printing out an exception's backtrace then reports both that exception and any "cause" exception. Rubinius has added a similar feature: https://gist.github.com/dbussink/b2e01e51d0c50b27004f The changes required for this feature are pretty benign: * Exception#cause and #cause= accessors. * A new set of Kernel#raise overloads that accept (as a trailing argument, probably) the "cause" exception. * Modifications to backtrace-printing logic to also display backtrace information from the "cause" exception (and in turn, from any nested "cause" exceptions). There's some discussion here about alternatives to #cause, none of which are quite as elegant as having it built in: http://www.skorks.com/2013/04/ruby-why-u-no-have-nested-exceptions/ -- http://bugs.ruby-lang.org/