[ruby-core:97843] [Ruby master Feature#11816] Partial safe navigation operator

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


FWIW, EcmaScript 2020 introduced a similar operator, see https://github.com/tc39/proposal-optional-chaining/
. The precedence is between `[]` and `*`, higher than I propose in https://bugs.ruby-lang.org/issues/11816#note-6 but at least low enough to be actually useful.

Matz, any chance we'll have a more useful operator precedence in Ruby 3?

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Feature #11816: Partial safe navigation operator
https://bugs.ruby-lang.org/issues/11816#change-85066

* Author: marcandre (Marc-Andre Lafortune)
* Status: Assigned
* Priority: Normal
* Assignee: matz (Yukihiro Matsumoto)
----------------------------------------
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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