go实现generator

这是一篇短文。

用过python的都知道generator，也就是生成器。生成器函数返回一个迭代器。那么如果用golang如何来实现呢？两种方法：channel和闭包。

package main

import (
    "fmt"
)

//implement generator by closure
func FibnacciClosure() func() (ret int) {
    a, b := 0, 1
    return func() (ret int) {
        ret = b
        a, b = b, a+b
        return
    }
}

//implement generator by channel
func FibnacciChan(n int) chan int {
    ret := make(chan int)

    go func() {
        a, b := 0, 1
        for i := 0; i < n; i++ {
            ret <- b
            a, b = b, a+b
        }
        close(ret)
    }()

    return ret
}

func main() {
    //closure
    nextFib := FibnacciClosure()
    for i := 0; i < 20; i++ {
        fmt.Println(nextFib())
    }

    //channel
    for i := range FibnacciChan(20) {
        fmt.Println(i)
    }
}