Softwareentwicklung in C++ - ASC

278 10. Memory – ein kleines Beispiel
93 ∗/
94 virtual OutputContext ∗ getOutputContextClone ( )
95 {
96 return ( output context . getClone ( ) ) ;
97 }
98 } ;
99
100
101 #endif // s i m p l e o u t p u t h a n d l i n g h
10.2.10 Displayable
Die Klasse SimpleOutputHandling arbeitet ausschließlich mit Elementen der
Klasse Displayable. Diese ist eine abstrakte Basisklasse, von der man darstellbare
Klassen entsprechend ableiten muss. Das Interface, das solche Klassen
dann implementieren müssen, ist sehr einfach:
1 // s i m p l e d i s p l a y a b l e . h − a simple a b s t r a c t base f o r a
2 // d i s p l a y a b l e o b j e c t
3
4 #ifndef s i m p l e d i s p l a y a b l e h
5 #define s i m p l e d i s p l a y a b l e h
6
7 #include ” simple output context . h”
8 class SimpleOutputHandling ;
9
10 //−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
11 /∗ The abstract base c l a s s f o r t e x t u a l l y d i s p l a y a b l e o b j e c t s ,
12 ∗ as i t i s used by SimpleOutputHandling
13 ∗/
14
15 class Displayable
16 {
17 public :
18
19 /∗ Destructor
20 ∗ Just to make sure that a v i r t u a l d e s t r u c t o r e x i s t s
21 ∗/
22 virtual ˜ Displayable ( ) { }
23
24 /∗ This c a l l b a c k i s used to n o t i f y a d i s p l a y a b l e that i t
25 ∗ has j u s t been r e g i s t e r e d with an output handler . I t can
26 ∗ perform a l l necessary operations in t h i s method to
27 ∗ be prepared to generate output .
28 ∗ @param handler The handler that t h i s d i s p l a y a b l e was
29 ∗ r e g i s t e r e d with .
30 ∗/
31 virtual void d i s p l a y a b l e R e g i s t e r e d (
32 SimpleOutputHandling &handler ) = 0 ;
33
34 /∗ The c a l l b a c k that i s c a l l e d by SimpleOutputHandling when
35 ∗ outputting the d i s p l a y a b l e s i s t r i g g e r e d .
36 ∗ @param context The output context to write to .
37 ∗/
38 virtual void writeDisplayRep ( OutputContext &context ) = 0 ;
39
40 } ;
41
42 #endif // s i m p l e d i s p l a y a b l e h