Added the Add function

README.md

@@ -16,6 +16,8 @@ package main
 
 import (
     "fmt"
+    "net/http"
+
     "github.com/pieterclaerhout/go-waitgroup"
 )
 
@@ -31,23 +33,69 @@ func main() {
 
     wg := waitgroup.NewWaitGroup(3)
 
-    for _, url := range urls {
-        wg.BlockAdd()
-        go func(url string) {
-            defer wg.Done()
-            fmt.Println("%s: checking", url)
-            res, err := http.Get(url)
-            if err != nil {
-                fmt.Println("Error: %v")
-            } else {
-                defer res.Body.Close()
-                fmt.Println("%s: result: %v", err)
-            }
-        }(url)
-    }
+	for _, url := range urls {
+		wg.BlockAdd()
+		go func(url string) {
+			defer wg.Done()
+			fmt.Printf("%s: checking\n", url)
+			res, err := http.Get(url)
+			if err != nil {
+				fmt.Println("Error: %v")
+			} else {
+				defer res.Body.Close()
+				fmt.Printf("%s: result: %v\n", url, err)
+			}
+		}(url)
+	}
 
     wg.Wait()
     fmt.Println("Finished")
 
 }
 ```
+
+There is also a way to use function closures to make it even more readable:
+
+```go
+package main
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/pieterclaerhout/go-waitgroup"
+)
+
+func main() {
+
+	urls := []string{
+		"https://www.easyjet.com/",
+		"https://www.skyscanner.de/",
+		"https://www.ryanair.com",
+		"https://wizzair.com/",
+		"https://www.swiss.com/",
+	}
+
+	wg := waitgroup.NewWaitGroup(3)
+
+	for _, url := range urls {
+
+		urlToCheck := url
+		wg.Add(func() {
+			fmt.Printf("%s: checking\n", urlToCheck)
+			res, err := http.Get(urlToCheck)
+			if err != nil {
+				fmt.Println("Error: %v")
+			} else {
+				defer res.Body.Close()
+				fmt.Printf("%s: result: %v\n", urlToCheck, err)
+			}
+		})
+
+	}
+
+	wg.Wait()
+	fmt.Println("Finished")
+
+}
+```

cmd/main.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/pieterclaerhout/go-waitgroup"
+)
+
+func main() {
+
+	urls := []string{
+		"https://www.easyjet.com/",
+		"https://www.skyscanner.de/",
+		"https://www.ryanair.com",
+		"https://wizzair.com/",
+		"https://www.swiss.com/",
+	}
+
+	wg := waitgroup.NewWaitGroup(3)
+
+	for _, url := range urls {
+
+		urlToCheck := url
+		wg.Add(func() {
+			fmt.Printf("%s: checking\n", urlToCheck)
+			res, err := http.Get(urlToCheck)
+			if err != nil {
+				fmt.Println("Error: %v")
+			} else {
+				defer res.Body.Close()
+				fmt.Printf("%s: result: %v\n", urlToCheck, err)
+			}
+		})
+
+	}
+
+	wg.Wait()
+	fmt.Println("Finished")
+
+}

waitgroup.go

@@ -26,12 +26,20 @@ func NewWaitGroup(size int) *WaitGroup {
 	return wg
 }
 
+// Add add the function close to the waitgroup
+func (wg *WaitGroup) Add(closure func()) {
+	wg.BlockAdd()
+	go func() {
+		defer wg.Done()
+		closure()
+	}()
+}
+
 // BlockAdd pushes ‘one’ into the group. Blocks if the group is full.
 func (wg *WaitGroup) BlockAdd() {
 	if wg.size > 0 {
 		wg.pool <- 1
 	}
-	// atomic.AddInt64(&wg.waitCount, 1)
 	wg.waitGroup.Add(1)
 }
 
@@ -40,7 +48,6 @@ func (wg *WaitGroup) Done() {
 	if wg.size > 0 {
 		<-wg.pool
 	}
-	// atomic.AddInt64(&wg.waitCount, -1)
 	wg.waitGroup.Done()
 }