1 files changed, 44 insertions, 0 deletions
diff --git a/src/sort/example_interface_test.go b/src/sort/example_interface_test.go
new file mode 100644
index 000000000..442204ea9
--- /dev/null
+++ b/src/sort/example_interface_test.go
@@ -0,0 +1,44 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package sort_test
+
+import (
+	"fmt"
+	"sort"
+)
+
+type Person struct {
+	Name string
+	Age  int
+}
+
+func (p Person) String() string {
+	return fmt.Sprintf("%s: %d", p.Name, p.Age)
+}
+
+// ByAge implements sort.Interface for []Person based on
+// the Age field.
+type ByAge []Person
+
+func (a ByAge) Len() int           { return len(a) }
+func (a ByAge) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+func (a ByAge) Less(i, j int) bool { return a[i].Age < a[j].Age }
+
+func Example() {
+	people := []Person{
+		{"Bob", 31},
+		{"John", 42},
+		{"Michael", 17},
+		{"Jenny", 26},
+	}
+
+	fmt.Println(people)
+	sort.Sort(ByAge(people))
+	fmt.Println(people)
+
+	// Output:
+	// [Bob: 31 John: 42 Michael: 17 Jenny: 26]
+	// [Michael: 17 Jenny: 26 Bob: 31 John: 42]
+}