The builder pattern is used to create complex objects with constituent parts that must be created in the same order or using a specific algorithm. An external class controls the construction algorithm.(建造者模式是用于创建复杂对象的组成部分,必须创建相同的顺序或使用一个特定的算法。一个外部类控制构造算法。)
class DeathStarBuilder {
var x: Double?
var y: Double?
var z: Double?
typealias BuilderClosure = (DeathStarBuilder) -> ()
init(buildClosure: BuilderClosure) {
buildClosure(self)
}
}
struct DeathStar : CustomStringConvertible {
let x: Double
let y: Double
let z: Double
init?(builder: DeathStarBuilder) {
if let x = builder.x, let y = builder.y, let z = builder.z {
self.x = x
self.y = y
self.z = z
} else {
return nil
}
}
var description:String {
return "Death Star at (x:\(x) y:\(y) z:\(z))"
}
}
/*:
### Usage
*/
let empire = DeathStarBuilder { builder in
builder.x = 0.1
builder.y = 0.2
builder.z = 0.3
}
let deathStar = DeathStar(builder:empire)
