decorator

Author: coolpest

.gitignore

@@ -13,3 +13,4 @@
 
 # Dependency directories (remove the comment below to include it)
 # vendor/
+/.idea

Decorator/main.go

@@ -0,0 +1,35 @@
+package Decorator
+
+import (
+	"log"
+	"math"
+	"time"
+)
+
+type piFunc func(int) float64
+
+func Wraplogger(fun piFunc,logger *log.Logger) piFunc{
+	return func(n int) float64{
+		fn:=func(n int)(result float64){
+			defer func(t time.Time){
+				logger.Printf("took=%v,n=%v,result=%v",time.Since(t),n,result)
+			}(time.Now())
+			return fun(n)
+		}
+		return fn(n)
+	}
+}
+
+func Pi(n int) float64{
+	ch := make(chan float64)
+	for k:=0;k<=n;k++{
+		go func(ch chan float64,k float64) {
+				ch<-4*math.Pow(-1,k)/(2*k+1)
+		}(ch,float64(k))
+	}
+	result :=0.0
+	for k:=0;k<=n;k++{
+		result +=<-ch
+	}
+	return result
+}

go.mod

@@ -0,0 +1,3 @@
+module github.com/i-coder-robot/design-patterns-in-golang
+
+go 1.13

main.go

@@ -0,0 +1,17 @@
+package main
+
+import (
+	"fmt"
+	"github.com/i-coder-robot/design-patterns-in-golang/Decorator"
+	"log"
+	"os"
+)
+
+func main(){
+	fmt.Println(Decorator.Pi(1000))
+	fmt.Println(Decorator.Pi(50000))
+
+	f:=Decorator.Wraplogger(Decorator.Pi,log.New(os.Stdout,"test",1))
+
+	f(100000)
+}