[ruby-core:97868] [Ruby master Feature#11816] Partial safe navigation operator

Issue #11816 has been updated by Dan0042 (Daniel DeLorme).


The `&.` operator has pretty well-defined semantics by now and changing it *may* break some existing code. Maybe a possible alternative would be a similar but separate operator like `&&.` / `and.` which would then intuitively have the same precedence as `&&` / `and`.

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Feature #11816: Partial safe navigation operator
https://bugs.ruby-lang.org/issues/11816#change-85092

* 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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