[BUG] Safe navigation for function calls throws a compile error

[EliteMasterEric]

ERROR source/funkin/play/cutscene/dialogue/DialogueBox.hx:157: characters 29-30
157 | typingCompleteCallback?.();
| ^
| Unexpected (

The accepted proposal for safe navigation provides for optional chaining to be used on function as well; if a function with a value of null would be called with ?.(), it will not be called, and return null instead if a return value is expected.

A cursory review of #10561 finds that this functionality was not implemented in the test cases. It may be that this was never properly implemented.

[EliteMasterEric]

Just learned the feature was left unimplemented, see here:

https://youtu.be/lkpoTcHKjSE?t=454

[alexeychikk]

Is safe navigation for call expression going to be implemented at all?

[T1mL3arn]

Maybe reopen the issue to be sort of a feature request? We have now obj?.prop, so would be nice to have obj.foo?.() instead of

if (obj.foo != null)
  obj.foo();

[EliteMasterEric]

Maybe reopen the issue to be sort of a feature request? We have now obj?.prop, so would be nice to have obj.foo?.() instead of

if (obj.foo != null)
  obj.foo();

See the explanation in the video. The main argument against ?.() is that the behavior of side effects is unclear, and in most user code, it is much rarer for functions to be null as opposed to objects (you would have to be working with anonymous structures or functions using the dynamic keyword).

[EliteMasterEric]

I made HaxeFoundation/haxe-evolution#114 as a home for discussion around ?.[] and ?.(). This issue can stay closed as the syntax is unimplemented, not bugged.