[ruby-core:83905] [Ruby trunk Feature#11816] Partial safe navigation operator

Issue #11816 has been updated by marcandre (Marc-Andre Lafortune).

Tracker changed from Bug to Feature
ruby -v deleted (preview 2)
Backport deleted (2.1: DONTNEED, 2.2: DONTNEED, 2.3: UNKNOWN)

Matz, did you get a chance to consider the precedence of `&.`?

As a reminder, there's currently no real use for `foo&.bar.baz` or similar. We are forced to write `foo&.bar&.baz` even though this could introduce unwanted errors, e.g. if `bar` was erroneously returning `nil`.

I still believe that my proposal https://bugs.ruby-lang.org/issues/11816#note-6 is the right one.

Thanks for the consideration.

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Feature #11816: Partial safe navigation operator
https://bugs.ruby-lang.org/issues/11816#change-67955

* Author: marcandre (Marc-Andre Lafortune)
* Status: Assigned
* Priority: Normal
* Assignee: matz (Yukihiro Matsumoto)
* Target version: 
----------------------------------------
I'm extremely surprised (and disappointed) that, currently:

```ruby
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

```js
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.




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