libgo/go/sort/example_interface_test.go

   1 // Copyright 2011 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package sort_test
   6
   7 import (
   8         "fmt"
   9         "sort"
  10 )
  11
  12 type Person struct {
  13         Name string
  14         Age  int
  15 }
  16
  17 func (p Person) String() string {
  18         return fmt.Sprintf("%s: %d", p.Name, p.Age)
  19 }
  20
  21 // ByAge implements sort.Interface for []Person based on
  22 // the Age field.
  23 type ByAge []Person
  24
  25 func (a ByAge) Len() int           { return len(a) }
  26 func (a ByAge) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
  27 func (a ByAge) Less(i, j int) bool { return a[i].Age < a[j].Age }
  28
  29 func Example() {
  30         people := []Person{
  31                 {"Bob", 31},
  32                 {"John", 42},
  33                 {"Michael", 17},
  34                 {"Jenny", 26},
  35         }
  36
  37         fmt.Println(people)
  38         sort.Sort(ByAge(people))
  39         fmt.Println(people)
  40
  41         // Output:
  42         // [Bob: 31 John: 42 Michael: 17 Jenny: 26]
  43         // [Michael: 17 Jenny: 26 Bob: 31 John: 42]
  44 }