so if developer want to capture an variable inference, must declare a new
variable.
class A {
var value = 1
func test() -> () -> Int {
var capturedValue = self.value
let editInfo = { () -> Int in
capturedValue += 1
return capturedValue
}
return editInfo
}
}
let a = A()
let editInfo = a.test()
print(editInfo()) // 2
print(a.value) // 1
print(editInfo()) // 3
print(a.value) // 1
what about:
class A {
var value = 1
func test() -> () -> Int {
let editInfo = { [inout value] () -> Int in
capturedValue += 1
return capturedValue
}
return editInfo
}
}
let a = A()
let editInfo = a.test()
print(editInfo()) // 2
print(a.value) // 2
print(editInfo()) // 3
print(a.value) // 3
> > On Oct 5, 2016, at 9:06 PM, Cao Jiannan via
> > swift-evolution<[email protected]>wrote:
> >
> > for example:
> >
> > var a = 1
> >
> > let block = { [inout a] in
> > a += 1
> > }
> >
> > block()
> > block()
> >
> > print(a) // 3
> This is already how captures work by default in closures and nested functions
> in Swift:
>
> var a = 1
>
> let block = { a += 1 }
>
> block()
> block()
>
> print(a) // prints 3
>
>
> If you want to capture something immutably you can put it in the capture list:
>
> var a = 1
> let block = { [a] in a += 1 } // error: left side of mutating operator isn't
> mutable: 'a' is a 'let' constant
>
> Mark
>
> >
> >
> > _______________________________________________
> > swift-evolution mailing list
> > [email protected]
> > https://lists.swift.org/mailman/listinfo/swift-evolution
>
>
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