feat: add CombineFuncs

Signed-off-by: Manfred Touron <94029+moul@users.noreply.github.com>

pattern.go

@@ -0,0 +1,13 @@
+package u
+
+// CombineFuncs create a chain of functions.
+// This can be particularly useful for creating cleanup function progressively.
+// It solves the infinite loop you can have when trying to do it manually: https://play.golang.org/p/NQem8UJ500t.
+func CombineFuncs(left func(), right ...func()) func() {
+	return func() {
+		left()
+		for _, fn := range right {
+			fn()
+		}
+	}
+}

pattern_test.go

@@ -0,0 +1,15 @@
+package u_test
+
+import (
+	"fmt"
+
+	"moul.io/u"
+)
+
+func ExampleCombineFuncs() {
+	cleanup := func() { fmt.Print("A") }
+	cleanup = u.CombineFuncs(cleanup, func() { fmt.Print("B") })
+	cleanup = u.CombineFuncs(func() { fmt.Print("C") }, cleanup)
+	cleanup()
+	// Output: CAB
+}