How should the "nullsafe" and "spread" member operators be formatted?

[lucaswerkmeister]

The regular member operator, ., is usually put on the start of the new line:

value result = mySequence
    .map(...)
    .filter(...)
    .fold(...);

How should this look for the nullsafe member operator ?. and the spread member operator *.?

[lucaswerkmeister]

Aligning the periods, 1

value result = mySequence
    .fold(...)
   ?.operation(...);

But this breaks my entire indentation architecture and just doesn’t work with tabs instead of spaces.

Aligning the periods, 2

value result = mySequence
    .fold(...)?
    .operation(...);

Unfortunately, this isn’t syntactically valid. I suppose it’s also hard to read.

Aligning the columns

value result = mySequence
    .fold(...)
    ?.operation(...);

That’s what the IDE’s indentation strategy does.

Operators on the previous line

value result = mySequence
    .fold(...)?.
    operation(...);

All operators on the previous line

value result = mySequence.
    fold(...)?.
    operation(...);

[lucaswerkmeister]

For now, I’ll go with Aligning the columns. I might add an option for All operators on the previous line later.

[gavinking]

Strangely, I kinda liked Aligning the periods, 2. But that would mean changing the grammar of the language. I think Aligning the columns is reasonable.

[lucaswerkmeister]

I’m kinda torn about Aligning the periods, 2 myself... I think it makes sense in a long call chain where you just don’t care if some intermediate result is null (“What, that’s optional? Fine, I’ll just add a ?. Ugh, that makes it all misaligned. Can’t I stick the ? up there?”), but if the null case is important (for example, if you’re assigning the result to some variable, maybe with an else clause as well), then I think that ? is too hidden and makes the code very unreadable.

[gavinking]

I don't think aligning the periods makes sense. More often you've got just one invocation, not a whole chain of them. Then for some crazy reason lines starting with ?. are indented differently to the rest of the code.

[lucaswerkmeister]

You mean 1? Yeah, I don’t like that one either. I don’t know why I put it first in the list...

[gavinking]

Ah, ok, yes, that's what I meant.

[gavinking]

Also, FTR, I don't like seeing lines ending in periods, it looks much too much like a full stop. And there's nothing warning you, if you just look at the next line, that it is a member reference you're seeing.

[lucaswerkmeister]

Good point. I don’t think that’s really used in Java either (Eclipse formatter doesn’t seem to have a setting for it), so I’ll just drop that and close the issue.