feat: add Future

pattern.go

@@ -18,3 +18,19 @@ func CheckErr(err error) {
 		panic(err)
 	}
 }
+
+// Future starts running the given function in background and return a chan that will return the result of the execution.
+func Future(fn func() (interface{}, error)) <-chan FutureRet {
+	c := make(chan FutureRet, 1)
+	go func() {
+		ret, err := fn()
+		c <- FutureRet{Ret: ret, Err: err}
+	}()
+	return c
+}
+
+// FutureRet is a generic struct returned by Future.
+type FutureRet struct {
+	Ret interface{}
+	Err error
+}

pattern_test.go

@@ -3,6 +3,7 @@ package u_test
 import (
 	"fmt"
 	"net/http"
+	"time"
 
 	"moul.io/u"
 )
@@ -19,3 +20,20 @@ func ExampleCheckErr() {
 	_, err := http.Get("http://foo.bar")
 	u.CheckErr(err) // panic
 }
+
+func ExampleFuture() {
+	future := u.Future(func() (interface{}, error) {
+		time.Sleep(100 * time.Millisecond)
+		return "foobar", nil
+	})
+
+	// here, we can do some stuff
+
+	ret := <-future
+	fmt.Println("Ret:", ret.Ret)
+	fmt.Println("Err:", ret.Err)
+
+	// Output:
+	// Ret: foobar
+	// Err: <nil>
+}