Jon_Shier
(Jon Shier)
1
Users:
I’m updating more code to beta 6 and have noticed a strange difference when calling functions with closure parameters where that closure is declared with a typealias. Take this class:
typealias Closure = () -> Void
class Thing {
var array: [String] =
func doClosure(closure: Closure) {
array.append("closure")
}
func doManualClosure(manualClosure: () -> Void) {
array.append("manualClosure")
}
func append() {
doClosure {
doClosure {
}
}
}
func appendManual() {
doManualClosure {
doManualClosure {
}
}
}
}
There’s an error triggered by the doClosure call inside a doClosure call saying that I need an explicit self capture. However, the same pattern in appendManual() builds just fine. I’m guessing this is a bug?
Jon
Jon_Shier
(Jon Shier)
2
Another general question I have is how the self requirement in general has changed. I’m noticing several instances where my previous @noescape closures, which of course had that attribute removed, are now requiring self when they didn’t before and aren’t marked @escaping either. So I guess my question is, should there ever be an instance where a closure not marked @escaping requires the use of self?
Jon
···
On Aug 19, 2016, at 5:46 PM, Jon Shier <jon@jonshier.com> wrote:
Users:
I’m updating more code to beta 6 and have noticed a strange difference when calling functions with closure parameters where that closure is declared with a typealias. Take this class:
typealias Closure = () -> Void
class Thing {
var array: [String] =
func doClosure(closure: Closure) {
array.append("closure")
}
func doManualClosure(manualClosure: () -> Void) {
array.append("manualClosure")
}
func append() {
doClosure {
doClosure {
}
}
}
func appendManual() {
doManualClosure {
doManualClosure {
}
}
}
}
There’s an error triggered by the doClosure call inside a doClosure call saying that I need an explicit self capture. However, the same pattern in appendManual() builds just fine. I’m guessing this is a bug?
Jon
Hi Jon,
In beta 6, non-escaping is now the default, and you must use the @escaping attribute to declare a parameter as escaping.
Unfortunately, there were a few bugs in how this attribute was implemented.
I checked in a fix to the swift-3.0-branch today: Sema: Three fixes for the new @escaping attribute · apple/swift@c1214fe · GitHub
After the above patch, it will no longer make a difference if the function type is written directly (as in doManualClosure) or a typealias (a in doClosure). In both cases, the closure should be non-escaping, unless explicitly declared @escaping. However in beta 6 you see the bug where the closure in doClosure() is escaping, even though no explicit @escaping attribute was specified, because it was written with a typealias.
If you have time, please test the next snapshot when it is released, or build Swift from swift-3.0-branch (or master) today, to see if it behaves as you expect.
Sorry for the confusion.
Slava
···
On Aug 19, 2016, at 5:27 PM, Jon Shier via swift-users <swift-users@swift.org> wrote:
Another general question I have is how the self requirement in general has changed. I’m noticing several instances where my previous @noescape closures, which of course had that attribute removed, are now requiring self when they didn’t before and aren’t marked @escaping either. So I guess my question is, should there ever be an instance where a closure not marked @escaping requires the use of self?
Jon
On Aug 19, 2016, at 5:46 PM, Jon Shier <jon@jonshier.com> wrote:
Users:
I’m updating more code to beta 6 and have noticed a strange difference when calling functions with closure parameters where that closure is declared with a typealias. Take this class:
typealias Closure = () -> Void
class Thing {
var array: [String] =
func doClosure(closure: Closure) {
array.append("closure")
}
func doManualClosure(manualClosure: () -> Void) {
array.append("manualClosure")
}
func append() {
doClosure {
doClosure {
}
}
}
func appendManual() {
doManualClosure {
doManualClosure {
}
}
}
}
There’s an error triggered by the doClosure call inside a doClosure call saying that I need an explicit self capture. However, the same pattern in appendManual() builds just fine. I’m guessing this is a bug?
Jon
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