sort: add a simpler sort.Interface example
Existing example renamed to Example_sortWrapper.
Fixes #6335.
R=golang-dev, rsc, taj.khattra, r
CC=golang-dev
https://golang.org/cl/13586043
diff --git a/src/pkg/sort/example_interface_test.go b/src/pkg/sort/example_interface_test.go
index 4c88821..c2feafe 100644
--- a/src/pkg/sort/example_interface_test.go
+++ b/src/pkg/sort/example_interface_test.go
@@ -9,69 +9,35 @@
"sort"
)
-type Grams int
-
-func (g Grams) String() string { return fmt.Sprintf("%dg", int(g)) }
-
-type Organ struct {
- Name string
- Weight Grams
+type Person struct {
+ Name string
+ Age int
}
-type Organs []*Organ
+func (p Person) String() string {
+ return fmt.Sprintf("%s: %d", p.Name, p.Age)
+}
-func (s Organs) Len() int { return len(s) }
-func (s Organs) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
+// ByAge implements sort.Interface for []Person based on
+// the Age field.
+type ByAge []*Person
-// ByName implements sort.Interface by providing Less and using the Len and
-// Swap methods of the embedded Organs value.
-type ByName struct{ Organs }
-
-func (s ByName) Less(i, j int) bool { return s.Organs[i].Name < s.Organs[j].Name }
-
-// ByWeight implements sort.Interface by providing Less and using the Len and
-// Swap methods of the embedded Organs value.
-type ByWeight struct{ Organs }
-
-func (s ByWeight) Less(i, j int) bool { return s.Organs[i].Weight < s.Organs[j].Weight }
+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 ExampleInterface() {
- s := []*Organ{
- {"brain", 1340},
- {"heart", 290},
- {"liver", 1494},
- {"pancreas", 131},
- {"prostate", 62},
- {"spleen", 162},
+ people := []*Person{
+ &Person{Name: "Bob", Age: 31},
+ &Person{Name: "John", Age: 42},
+ &Person{Name: "Michael", Age: 17},
+ &Person{Name: "Jenny", Age: 26},
}
- sort.Sort(ByWeight{s})
- fmt.Println("Organs by weight:")
- printOrgans(s)
+ fmt.Println(people)
+ sort.Sort(ByAge(people))
+ fmt.Println(people)
- sort.Sort(ByName{s})
- fmt.Println("Organs by name:")
- printOrgans(s)
-
- // Output:
- // Organs by weight:
- // prostate (62g)
- // pancreas (131g)
- // spleen (162g)
- // heart (290g)
- // brain (1340g)
- // liver (1494g)
- // Organs by name:
- // brain (1340g)
- // heart (290g)
- // liver (1494g)
- // pancreas (131g)
- // prostate (62g)
- // spleen (162g)
-}
-
-func printOrgans(s []*Organ) {
- for _, o := range s {
- fmt.Printf("%-8s (%v)\n", o.Name, o.Weight)
- }
+ // Output: [Bob: 31 John: 42 Michael: 17 Jenny: 26]
+ // [Michael: 17 Jenny: 26 Bob: 31 John: 42]
}
diff --git a/src/pkg/sort/example_wrapper_test.go b/src/pkg/sort/example_wrapper_test.go
new file mode 100644
index 0000000..cf6d74c
--- /dev/null
+++ b/src/pkg/sort/example_wrapper_test.go
@@ -0,0 +1,77 @@
+// 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 Grams int
+
+func (g Grams) String() string { return fmt.Sprintf("%dg", int(g)) }
+
+type Organ struct {
+ Name string
+ Weight Grams
+}
+
+type Organs []*Organ
+
+func (s Organs) Len() int { return len(s) }
+func (s Organs) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
+
+// ByName implements sort.Interface by providing Less and using the Len and
+// Swap methods of the embedded Organs value.
+type ByName struct{ Organs }
+
+func (s ByName) Less(i, j int) bool { return s.Organs[i].Name < s.Organs[j].Name }
+
+// ByWeight implements sort.Interface by providing Less and using the Len and
+// Swap methods of the embedded Organs value.
+type ByWeight struct{ Organs }
+
+func (s ByWeight) Less(i, j int) bool { return s.Organs[i].Weight < s.Organs[j].Weight }
+
+func Example_sortWrapper() {
+ s := []*Organ{
+ {"brain", 1340},
+ {"heart", 290},
+ {"liver", 1494},
+ {"pancreas", 131},
+ {"prostate", 62},
+ {"spleen", 162},
+ }
+
+ sort.Sort(ByWeight{s})
+ fmt.Println("Organs by weight:")
+ printOrgans(s)
+
+ sort.Sort(ByName{s})
+ fmt.Println("Organs by name:")
+ printOrgans(s)
+
+ // Output:
+ // Organs by weight:
+ // prostate (62g)
+ // pancreas (131g)
+ // spleen (162g)
+ // heart (290g)
+ // brain (1340g)
+ // liver (1494g)
+ // Organs by name:
+ // brain (1340g)
+ // heart (290g)
+ // liver (1494g)
+ // pancreas (131g)
+ // prostate (62g)
+ // spleen (162g)
+}
+
+func printOrgans(s []*Organ) {
+ for _, o := range s {
+ fmt.Printf("%-8s (%v)\n", o.Name, o.Weight)
+ }
+}
