1 using System;
2
3 class Originator
4 {
5 private double manufacturer=0;
6 private double distributor = 0;
7 private double retailer = 0;
8
9 public void MakeSale(double purchasePrice)
10 {
11 // We assume sales are divided equally amount the three
12 manufacturer += purchasePrice * .40;
13 distributor += purchasePrice *.3;
14 retailer += purchasePrice *.3;
15 // Note: to avoid rounding errors for real money handling
16 // apps, we should be using decimal integers
17 // (but hey, this is just a demo!)
18 }
19
20 public Memento CreateMemento()
21 {
22 return (new Memento(manufacturer, distributor, retailer));
23 }
24
25 public void SetMemento(Memento m)
26 {
27 manufacturer = m.A;
28 distributor = m.B;
29 retailer = m.C;
30 }
31 }
32
33 class Memento
34 {
35 private double iA;
36 private double iB;
37 private double iC;
38
39 public Memento(double a, double b, double c)
40 {
41 iA = a;
42 iB = b;
43 iC = c;
44 }
45
46 public double A
47 {
48 get
49 {
50 return iA;
51 }
52 }
53
54 public double B
55 {
56 get
57 {
58 return iB;
59 }
60 }
61
62 public double C
63 {
64 get
65 {
66 return iC;
67 }
68 }
69 }
70
71 class caretaker
72 {
73
74 }
75
76 /// <summary>
77 /// Summary description for Client.
78 /// </summary>
79 public class Client
80 {
81 public static int Main(string[] args)
82 {
83 Originator o = new Originator();
84
85 // Assume that during the course of running an application
86 // we we set various data in the originator
87 o.MakeSale(45.0);
88 o.MakeSale(60.0);
89
90 // Now we wish to record the state of the object
91 Memento m = o.CreateMemento();
92
93 // We make further changes to the object
94 o.MakeSale(60.0);
95 o.MakeSale(10.0);
96 o.MakeSale(320.0);
97
98 // Then we decide ot change our minds, and revert to the saved state (and lose the changes since then)
99 o.SetMemento(m);
100
101 return 0;
102 }
103 }
