// Code from my dotGo.eu 2014 presentation
//
// Copyright (c) 2014 John Graham-Cumming
//
// Implement a factory and a task. Call run() on your factory.

package main

import (
	"bufio"
	"log"
	"os"
	"sync"
)

type task interface {
	process()
	print()
}

type factory interface {
	make(line string) task
}

func run(f factory) {
	var wg sync.WaitGroup

	in := make(chan task)

	wg.Add(1)
	go func() {
		s := bufio.NewScanner(os.Stdin)
		for s.Scan() {
			in <- f.make(s.Text())
		}
		if s.Err() != nil {
			log.Fatalf("Error reading STDIN: %s", s.Err())
		}
		close(in)
		wg.Done()
	}()

	out := make(chan task)

	for i := 0; i < 1000; i++ {
		wg.Add(1)
		go func() {
			for t := range in {
				t.process()
				out <- t
			}
			wg.Done()
		}()
	}

	go func() {
		wg.Wait()
		close(out)
	}()

	for t := range out {
		t.print()
	}
}

func main() {
	// run(&myFactory{})
}

// Code from my dotGo.eu 2014 presentation
//
// Copyright (c) 2014 John Graham-Cumming
//
// Implement a factory and a task. Call run() on your factory.

package main

import (
	"bufio"
	"log"
	"os"
	"sync"
)

type task interface {
	process()
	print()
}

type factory interface {
	make(line string) task
}

func run(f factory) {
	var wg sync.WaitGroup

	in := make(chan task)

	wg.Add(1)
	go func() {
		s := bufio.NewScanner(os.Stdin)
		for s.Scan() {
			in <- f.make(s.Text())
		}
		if s.Err() != nil {
			log.Fatalf("Error reading STDIN: %s", s.Err())
		}
		close(in)
		wg.Done()
	}()

	out := make(chan task)

	go func() {
		for t := range out {
			t.print()
		}
	}()

	for i := 0; i < 1000; i++ {
		wg.Add(1)
		go func() {
			for t := range in {
				t.process()
				out <- t
			}
			wg.Done()
		}()
	}

	wg.Wait()
	close(out)
}

func main() {
	// run(&myFactory{})
}

--- 
+++ 
@@ -42,12 +42,6 @@
 
 	out := make(chan task)
 
-	go func() {
-		for t := range out {
-			t.print()
-		}
-	}()
-
 	for i := 0; i < 1000; i++ {
 		wg.Add(1)
 		go func() {
@@ -59,8 +53,14 @@
 		}()
 	}
 
-	wg.Wait()
-	close(out)
+	go func() {
+		wg.Wait()
+		close(out)
+	}()
+
+	for t := range out {
+		t.print()
+	}
 }
 
 func main() {
Add improvement from eneff that makes program terminate more cleanly
