[swift-users] cast operator precedence

[Elena Vilchik]

Hello Jens,

Thanks for an answer. Anyway it's confusing to have this "as ___" operator
among infix operators
<https://developer.apple.com/library/prerelease/ios/documentation/Swift/Reference/Swift_StandardLibrary_Operators/index.html#//apple_ref/doc/uid/TP40016054>
and as binary-expression
<https://developer.apple.com/library/mac/documentation/Swift/Conceptual/Swift_Programming_Language/Expressions.html#//apple_ref/swift/grammar/binary-expression>
.

2015-12-04 20:30 GMT+01:00 Jens Alfke <jens at mooseyard.com>:

>
> On Dec 4, 2015, at 3:21 AM, Elena Vilchik <vilchik.elena at gmail.com> wrote:
>
> I've found here
> <https://developer.apple.com/library/prerelease/ios/documentation/Swift/Reference/Swift_StandardLibrary_Operators/index.html#//apple_ref/doc/uid/TP40016054>
>  that "as" operator has a lower precedence than "*" operator (132 vs 160).
> Why then this code compiles if multiplication should be made first?
>
> var x = 1
> print(x as Int * 100)
>
>
> “as ___” is a *postfix* operator (the following type name has to be
> considered part of the ‘as’.) So there’s only one way to parse that
> expression as valid Swift, and thus the parser doesn’t even have to look at
> operator precedence.
>
> In other words, `x as (Int * 100)` isn’t valid Swift syntax, so the parser
> doesn’t even consider it.
>
> —Jens
>
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