refactor: common ifaces

interfaces/09-little-refactor/timestamp.go

@@ -0,0 +1,45 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"strconv"
+	"time"
+)
+
+// timestamp stores, formats and automatically prints a timestamp.
+type timestamp struct {
+	// timestamp anonymously embeds a time.
+	// no need to convert a time value to a timestamp value to use the methods of the time type.
+	time.Time
+}
+
+func (ts timestamp) string() string {
+	if ts.IsZero() { // same as: ts.Time.IsZero()
+		return "unknown"
+	}
+
+	// Mon Jan 2 15:04:05 -0700 MST 2006
+	const layout = "2006/01"
+	return ts.Format(layout) // same as: ts.Time.Format(layout)
+}
+
+// toTimestamp returns a timestamp value depending on the type of `v`.
+func toTimestamp(v interface{}) (ts timestamp) {
+	var t int
+
+	switch v := v.(type) {
+	case int:
+		t = v
+	case string:
+		t, _ = strconv.Atoi(v)
+	}
+
+	ts.Time = time.Unix(int64(t), 0)
+	return ts
+}