第一次接触Ruby看到这样的表达式的时候, 确实有点惊呆了
3.times { print "Hi!" }
1.upto(9) {|i| print i }
0.step(11,3) {|i| print i }
(1..9).each {|i| print i }
最近学看Swift的时候发现, Swift也可以搞得跟Ruby有点儿像.
先看看Swift里可以怎么写
0.upto(10) { print("upto\($0)") }
10.downto(0) { print("downto") }
10.times { print("Hello")}
10.times { index in print("Hello\(index)") }
(1...10).each { print("each\($0)") }
当然, 你要是想直接就上这样的代码, 十有八九编译器是要报错的.
不过, 只要加上下面这一小段代码之后, 情况就好很多了.
import Foundation
extension Int {
public func upto(to: Int, action: (Int)->Void) {
for i in self...to {
action(i)
}
}
public func upto(to: Int, action: ()->Void) {
for _ in self...to {
action()
}
}
public func downto(to: Int, action: (Int)->Void) {
for i in to...self {
action(i)
}
}
public func downto(to: Int, action: ()->Void) {
for _ in to...self {
action()
}
}
public func times(action: (Int)->Void) {
for i in 0..<self {
action(i)
}
}
public func times(action: ()->Void) {
for _ in 0..<self {
action()
}
}
}
extension Range {
public func each(action: (Range.Generator.Element) -> Void) {
for i in self {
action(i)
}
}
}
不禁感概, 这个extension也太霸道了.
再结合一点儿自定义运算符, 运算符重载什么的, 以后用Swift写的东西可不是每个懂Swift语言的人都能看得懂了:)
抛个砖先放这里, 等吃透了可变参数以及Tuple之后, 再回头看看这块砖~
或许我们可以用Python的%格式化字符串的方式来格式化Swift的字符串哦~
public func %<T: CVarArgType>(format: String, args: T) -> String {
return String(format: format, arguments: [args])
}
public func %(format: String, args: [CVarArgType]) -> String {
return String(format: format, arguments: args)
}
let s1 = "Python style %d" % 10;
print("\(s1)")
let s2 = "Python style %d %@" % [10, "monster"];
print("\(s2)")
这个使用形式上还有些不是完全的Python味道.