-
Notifications
You must be signed in to change notification settings - Fork 0
/
observer.go
74 lines (60 loc) · 1.18 KB
/
observer.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
package main
import (
"container/list"
"fmt"
)
type Observable struct {
subs *list.List
}
func (o *Observable) Subscribe(x Observer) {
o.subs.PushBack(x)
}
func (o *Observable) Unsubscribe(x Observer) {
for z := o.subs.Front(); z != nil; z = z.Next() {
if z.Value.(Observer) == x {
o.subs.Remove(z)
}
}
}
func (o *Observable) Fire(data interface{}) {
for z := o.subs.Front(); z != nil; z = z.Next() {
z.Value.(Observer).Notify(data)
}
}
// ---------------
// Observer that knows
// how to send notification
// ---------------
type Observer interface {
Notify(data interface{})
}
// ---------------
// real life Example
// ---------------
// whenever a person catches a cold,
// a doctor must be called
type Person struct {
Observable
Name string
}
func NewPerson(name string) *Person {
return &Person{
Observable: Observable{new(list.List)},
Name: name,
}
}
func (p *Person) CatchACold() {
p.Fire(p.Name)
}
type DoctorService struct{}
func (d *DoctorService) Notify(data interface{}) {
fmt.Printf("A doctor has been called for %s",
data.(string))
}
func main() {
p := NewPerson("Boris")
ds := &DoctorService{}
p.Subscribe(ds)
// test
p.CatchACold()
}