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@safx
Created October 20, 2015 11:51
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lazy in Swift
class Foo {
static var x: Int = 0
lazy var a: Int! = { return x++ }()
}
class Bar {
static var y: Int = 0
lazy var b: Int? = { return y++ }()
}
let f = Foo()
print(f.a)
f.a = nil
print(f.a)
let g = Bar()
print(g.b)
g.b = nil
print(g.b)
import Foundation
class Foo {
static var x: Int = 0
var lazy_a: Optional<Int!>
var a: Int! {
get { // main.Foo.a.getter
let val: Int!
if self.lazy_a != nil { // bb0
switch self.lazy_a {// bb1
case .Some(let v): // bb2
val = v // bb5
case .None: // bb3, bb4
fatalError("unexpectedly found nil while unwrapping an Optional value")
}
} else { // bb6
let v = { return Foo.x++ }()
val = .Some(v)
let tmp: Optional<Int!>
switch val {
case .Some: // bb7
tmp = .Some(.Some(val))
case .None: // bb9
tmp = .None
}
self.lazy_a = tmp // bb8
}
return val // bb10
}
set { // main.Foo.a.setter
switch newValue {
case .None: self.lazy_a = nil
case .Some(let v): self.lazy_a = .Some(.Some(v))
}
}
}
}
let f = Foo()
print(f.a)
f.a = nil
print(f.a)
class Bar {
static var y: Int = 0
var lazy_b: Optional<Int?>
var b: Int? {
get {
if self.lazy_b == nil {
let v = { return Bar.y++ }()
self.lazy_b = .Some(.Some(v))
}
return self.lazy_b!
}
set {
self.lazy_b = .Some(newValue)
}
}
}
let g = Bar()
print(g.b)
g.b = nil
print(g.b)
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