clarify documentation for @view

[simeonschaub]

There was some confusion about this on Slack for the case of broadcasted assignment.

[mbauman]

I don't really like calling out broadcast here as it's a no-op. Broadcast already does it for you.

[mbauman]

Oh, I missed the emphasis on updating broadcasts. Yes, that usage makes sense... but maybe we should just do it by default anyways?

[simeonschaub]

I don't really like calling out broadcast here as it's a no-op. Broadcast already does it for you.

Not for the @view(A[1, 2:end]) .*= 2 example though, because it's allocating otherwise. I do really like all your other suggestions, I think it explains the purpose of this macro much better.

[simeonschaub]

but maybe we should just do it by default anyways?

Yeah, I thought about this before as well. It would violate the assumption that A[idx] .*= 2 is just equivalent to A[idx] .= A[idx] .* 2, although that's already not true if you have any function with side effects on the lhs.

[simeonschaub]

@mbauman Do you still think we should not mention the @view(A[1, 2:end]) .*= 2 example here? If so, I'd just go ahead with your suggestions, but personally, I think it wouldn't hurt to mention that example here as well, since I find it a bit non-obvious. I don't feel to strongly about this though.

[mbauman]

Yeah, I think it's fine and even helpful to mention — my review was thinking this was calling out the difference between = and .=. I've edited my suggestion above. It's pretty wordy, but it's an attempt at making this a bit clearer.