[ruby-core:75676] [Ruby trunk Bug#12412] Extend safe navigation operator

Issue #12412 has been updated by Daniel Ferreira.


Another improvement to make it even more powerful.

Introduction of a new global variable that would return the object which didn't respond to the method breaking the safe navigation chain.
Although we need to think about concurrency as well and performance.

Just an idea:

~~~ ruby
foo = ''

def foo.bar
   1
end

foo&.bar&.baz
# => nil
$NEW_GLOBAL_VARIABLE_OR_SOMETHING_ELSE
# => 1
~~~

----------------------------------------
Bug #12412: Extend safe navigation operator
https://bugs.ruby-lang.org/issues/12412#change-58808

* Author: Daniel Ferreira
* Status: Open
* Priority: Normal
* Assignee: 
* ruby -v: 
* Backport: 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN
----------------------------------------
I wonder if we couldn't extend the safe navigation operator to work with any object rather than just nil.

I tend to still use this kind of code in some scenarios, specially when I work with objects with dynamic interfaces or arguments with different possible object types:

~~~ ruby
class Foo
   def bar(baz)
       if baz.respond_to?(:qux)
          return baz.qux
       end
       'whatever'
   end
end
~~~

What if we extend the safe navigation operator to work with any kind of object?
If it doesn't respond to the method it would return nil like this:

~~~ ruby
class Foo
  def bar(baz)
    baz&.qux || 'whatever'
  end
end
~~~

In order to not break backwards compatibility we should keep the current behaviour as well so the rational would be:

~~~ ruby
nil&.any_method
# => nil

foo&.non_responding_method
# => nil
~~~




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