go-patterns/concurrency/generator.md

Generator Pattern

Generators yields a sequence of values one at a time.

Implementation

func Count(start int, end int) chan int {
    ch := make(chan int)

    go func(ch chan int) {
        for i := start; i < end ; i++ {
            // Blocks on the operation
            ch <- i
        }

		close(ch)
	}(ch)

	return ch
}

Usage

fmt.Println("No bottles of beer on the wall")

for i := range Count(1, 99) {
    fmt.Println("Pass it around, put one up,", i, "bottles of beer on the wall")
    // Pass it around, put one up, 1 bottles of beer on the wall
    // Pass it around, put one up, 2 bottles of beer on the wall
    // ...
    // Pass it around, put one up, 99 bottles of beer on the wall
}

fmt.Println(100, "bottles of beer on the wall")