Optimization Question: Dealing with multiple returns

[frogofdoom]

Warning: this is a fine point of optimization, and I suspect that the difference is purely academic.

That said, when you only need one of the returns from a function with multiple returns (i.e. return var1, var2; ), which of these is better, memory-wise and/or CPU-wise:

This one, which seems to be the preferred way of doing it now:

local someVar = select(2, SomeFunction())

or this one, which I used to see in older code:

local _, someVar = SomeFunction()

The only reason I'm asking is that I typically figure that avoiding function calls if you don't need them is a good idea, but most good code that I've looked at lately uses select().

I'd appreciate any light anyone can shed on this. Thanks in advance.

[Seerah]

Actually, neither of those are "older" or "current". They just are two different ways of doing it.

This:

local _, var = foo()

avoids a function call.


It totally depends on how often you are calling foo() and needing the second return. If it's not often, then using select() makes no difference. If it's in a frequent OnUpdate, using a toss away variable might be more efficient.

Ultimately, though, you're talking about fractions of a millisecond of a difference.

[frogofdoom]

Thanks for answering. That sounds reasonable.