> On 12 Jun 2015, at 08:49, Roland King <[email protected]> wrote:
>
> Trying out some of the new Swift 2 features for pattern matching (What’s New
> In Swift around the 19m 35s + mark with Chris Lattner) but not having much
> success. I have this in a playground
>
> enum test
> {
> case one
> case two( Int )
> case three( String, Int )
> }
>
> let x = [ test.one, test.two( 123 ), test.three( "xx", 1 ), test.one,
> test.three( "rrr", 7 ), test.two( 9 ) ]
>
> for case test.two( let a ) in x
> {
> print( "a is \(a) " )
> }
>
> Which follows the pattern shown on-screen, as I understand it at least, and
> in the updated Swift beta 2 book
>
> I get numerous errors on the ‘for case .’ line, the compiler clearly thinks
> the entire line is garbage. I’ve tried taking the ‘case’ word out, that
> doesn’t work, I’ve tried taking the ‘test.’ off the start of ‘test.two’,
> still no good, possibly worse.
>
> Tried a simple version in an if as well
>
> let y = test.two( 123 )
>
>
> if case test.two( let a ) == y { } // variable binding in
> a condition requires an initializer
>
>
> I must have tried 10 other combinations as well without any success. I must
> have entirely misunderstood the new uniform case pattern matching, or it
> doesn’t work in seed 1. The ‘if case’ construct is going to be quite useful,
> anyone else have more success?
I can answer the second half of my own question
let y = test.two( 123 )
if case test.two( let a ) = y {}
yes ‘=‘ instead of ‘==‘. I hit on that trying random things and don’t really
understand it, an ‘=‘ in an if() test is something I’m having trouble getting
my brain around.
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