From: mame@... Date: 2015-12-14T23:47:11+00:00 Subject: [ruby-core:72122] [Ruby trunk - Bug #11816] Partial safe navigation operator Issue #11816 has been updated by Yusuke Endoh. It seems very sensitive to determine how long it propagates. How should we interpret `str&.upcase + "foo"`? If it is considered as `str&.upcase&.+("foo")`, it may return nil (as I expect). If it is considered as `(str&.upcase) + "foo"`, it may raise an exception. We need write `p str&.upcase&.+("foo")`. How's that for `str&.upcase == nil`? If it is considered as `str&.upcase&.==(nil)`, it will return false or nil. Very confusing. If it is considered as `(str&.upcase) == nil`, it will return true or false. -- Yusuke Endoh ---------------------------------------- Bug #11816: Partial safe navigation operator https://bugs.ruby-lang.org/issues/11816#change-55537 * Author: Marc-Andre Lafortune * Status: Open * Priority: Normal * Assignee: Yukihiro Matsumoto * ruby -v: preview 2 * Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN ---------------------------------------- I'm extremely surprised (and disappointed) that, currently: x = nil x&.foo.bar # => NoMethodError: undefined method `bar' for nil:NilClass To make it safe, you have to write `x&.foo&.bar`. But if `foo` is never supposed to return `nil`, then that code isn't "fail early" in case it actually does. `nil&.foo.bar` is more expressive, simpler and is perfect if you want to an error if `foo` returned `nil`. To actually get what you want, you have to resort using the old form `x && x.foo.bar`... In CoffeeScript, you can write `x()?.foo.bar` and it will work well, since it gets compiled to if ((_ref = x()) != null) { _ref.foo.bar; } All the discussion in #11537 focuses on `x&.foo&.bar`, so I have to ask: Matz, what is your understanding of `x&.foo.bar`? I feel the current implementation is not useful and should be changed to what I had in mind. I can't see any legitimate use of `x&.foo.bar` currently. -- https://bugs.ruby-lang.org/