Christoffer Lernö

.@mjtsai you OFTEN want the way Swift acts but it is not explicit, and something I always try to avoid is code that isn't obvious enough.

@nuoji Why do you say "not explicit"? Because the "var" may be textually far away?

@mjtsai var arrays will try to optimize for you, so the actual runtime perf and behavior will depend on subtle variations to your code.

@nuoji Yes, agreed about the perf being more hidden. I thought you were talking about "explicit" when reading the code.

@mjtsai compare ObjC - switching between mutable and immutable is completely explicit and inspectable. Including when passing arrays as args

@nuoji Aren't "var" and "inout" just different ways of spelling "mutable"? That's explicit.

@mjtsai it only describes the language rules, it does not describe the behavior of the underlying runtime.

@nuoji Yep. To me, the questions are 1. How much does the perf difference usually matter, and 2. Is there an escape hatch when it bites you.

@mjtsai It's a problem of "magic" code too. There is a lot of it built into language - auto closures and return overload are the worst.