IObservable

1 class ObservableNumber : IObservable!int
2 {
3     private int number;
4     private IObserver!int[] observers;
5 
6     private void publish()
7     {
8         foreach (o; observers)
9             o.onNext(this.number);
10     }
11 
12     int opUnary(string op)()
13     {
14         this.number = mixin (op ~ "this.number");
15         publish();
16         return this.number;
17     }
18 
19     int opBinary(string op, T)(T other) const
20         if (is(T : int))
21     {
22         return mixin ("this.number" ~ op ~ "other");
23     }
24 
25     int opAssign(T)(T other) if (is(T : int))
26     {
27         this.number = other;
28         publish();
29         return this.number;
30     }
31 
32     int opOpAssign(string op, T)(T other) if (is(T : int))
33     {
34         mixin ("this = this " ~ op ~ " other;");
35         return this.number;
36     }
37 
38     class Ticket : IDisposable
39     {
40         this(size_t idx) { this.idx = idx; }
41         private const size_t idx;
42         bool dispose()
43         {
44             if (this.outer.observers[idx] !is null)
45             {
46                 this.outer.observers[idx] = null;
47                 return true;
48             }
49             else
50                 return false;
51         }
52     }
53 
54     IDisposable subscribe(IObserver!int o)
55     {
56         observers ~= o;
57         o.onNext(this.number);
58         return new Ticket(observers.length - 1);
59     }
60 }
61 
62 class NumberObserver : IObserver!int
63 {
64     int[] result;
65     void onNext(int x) { result ~= x; }
66     void onError(Exception error) { assert (0); }
67     void onCompleted() { assert (0); }
68 }
69 
70 auto observervable = new ObservableNumber;
71 auto observer = new NumberObserver;
72 
73 auto ticket = observervable.subscribe(observer);
74 assert ((cast(ObservableNumber.Ticket)ticket).idx == 0);
75 assert (observervable.observers.length == 1);
76 assert (observer.result == [ 0 ]);
77 
78 observervable++;
79 observervable += 3;
80 observervable *= 2;
81 
82 assert (observervable.number == 8);
83 assert (observer.result == [ 0, 1, 4, 8 ]);