4:Fronting for an implementation 49
Proxy..................................50
State...................................52
StateMachine.....................54
Table-Driven State Machine61
The State class..............................63
Conditions for transition..............63
Transition actions.........................64
The table.......................................64
The basic machine........................65
Simple vending machine..............65
Testing the machine.....................70
Tools...................................70
Exercises............................70
X: Decorators: dynamic type selection 72
Basic decorator structure..73
A coffee example................73
Class for each combination73
The decorator approach....76
Compromise ......................79
Other considerations.........82
Exercises............................82
Y: Iterators: decoupling algorithms from containers 83
Type-safe iterators.............84
5: Factories: encapsulating object creation 85
Simple Factory method.....86
Polymorphic factories ...... 88
Abstract factories.............. 90
Exercises............................93
6: Function objects 94
Command: choosing the operation at run-time 94
Strategy: choosing the algorithm at run-time 96
Chain of responsibility ......97
Exercises.......................... 101
7: Changing the interface 101
Adapter ............................ 101
Façade..............................103
Exercises..........................104
