Merge https://github.com/restudy/go-patterns

creational/factory_method.go

@@ -0,0 +1,33 @@
+package data
+
+import "io"
+
+type Store interface {
+    Open(string) (io.ReadWriteCloser, error)
+}
+
+
+type StorageType int
+
+const (
+    DiskStorage StorageType = 1 << iota
+    TempStorage
+    MemoryStorage
+)
+
+func NewStore(t StorageType) Store {
+    switch t {
+    case MemoryStorage:
+        return newMemoryStorage( /*...*/ )
+    case DiskStorage:
+        return newDiskStorage( /*...*/ )
+    default:
+        return newTempStorage( /*...*/ )
+    }
+}
+
+s, _ := NewStore(data.MemoryStorage)
+f, _ := s.Open("file")
+
+n, _ := f.Write([]byte("data"))
+defer f.Close()

creational/object_pool.go

@@ -0,0 +1,27 @@
+package pool
+
+type Pool chan *Object
+
+func New(total int) *Pool {
+	p := make(Pool, total)
+
+	for i := 0; i < total; i++ {
+		p <- new(Object)
+	}
+
+	return &p
+}
+
+
+
+p := New(2)
+
+select {
+case obj := <-p:
+	obj.Do( /*...*/ )
+
+	p <- obj
+default:
+	// No more objects left — retry later or fail
+	return
+}

profiling/profile.go

@@ -0,0 +1,25 @@
+package profile
+
+import (
+    "time"
+    "log"
+)
+
+func Duration(invocation time.Time, name string) {
+    elapsed := time.Since(invocation)
+
+    log.Printf("%s lasted %s", name, elapsed)
+}
+
+func BigIntFactorial(x big.Int) *big.Int {
+    // Arguments to a defer statement is immediately evaluated and stored.
+    // The deferred function receives the pre-evaluated values when its invoked.
+    defer Duration(time.Now(), "IntFactorial")
+
+    y := big.NewInt(1)
+    for one := big.NewInt(1); x.Sign() > 0; x.Sub(x, one) {
+        y.Mul(y, x)
+    }
+
+    return x.Set(y)
+}

structural/decorate.go

@@ -0,0 +1,28 @@
+package main
+
+type Object func(int) int
+
+func LogDecorate(fn Object) Object {
+	return func(n int) int {
+		log.Println("Starting the execution with the integer", n)
+
+		result := fn(n)
+
+		log.Println("Execution is completed with the result", result)
+
+        return result
+	}
+}
+
+func Double(n int) int {
+    return n * 2
+}
+
+func main(){
+  f := LogDecorate(Double)
+  f(5)
+}
+
+
+// Starting execution with the integer 5
+// Execution is completed with the result 10